Quick comment regarding your short side example of filling it in. You can fill that in to let the air straighten itself out before hitting the throat/seat. The part you may be leaving out (or not) is that you should also widen that part of the port to keep the area the same. I agree with you that restricting the flow is bollix. Raise the short side but widen it at the same time. 2 cents from an old geezer. The "restriction" should be the valve throat. That's where you want to speed up the air (in the throat). The throat should be the smallest part of the entire port. Cheers. -Matt
The proof is in testing and experimentation. He needs to prove his theory. I know from experience too large a port hurts drive-ability and too small can limit power.. it’s all about balance and where you want the torque.
Great vid man! Ive been taught that its about where in the RPM you want your power band. As in the smaller or ''restrictive'' port is good for low rpm torque but sacrifices high RPM power, due to having high velocity at lower RPM but unable to produce enough volume for the higher RPM.
It’s not about reducing the port size it’s about keeping the bend smooth. If the bend is too tight the flow will delaminates and cause turbulence, this turbulence will drastically reduce the flow rates.
Well explained! People think high velocity means more air... there is a reason why cylinder head manufacturers advertise volume and cfm... on a fire truck the pumps are rated at 150 psi for max volume and when you go up to 200 and 250 psi the volume of water goes down... if you want more power you need to remove the restrictions
I been porting 25 years and your right on it ..it's all about shapes Port design heights what to remove so much more I really like porting 2 stroke banshees
@@brianhaygood183 we forgot Reynold's Number (!) LOL (Actually just a few weeks ago when thinking about a flow problem, it struck me that at lower speeds, viscosity dominated while at higher speeds, inertia. And then I reread the definition of RN and guess what? RN is used to determine what regime the flow is in! My fluid dynamics professor could have made that point crystal, especially since it is a monumental and very intuitive metric. But Noooooooo....
At the end of the day it all depends on valve size and port shape and port size, smaller ports will make more power AT a lower rpm but you will restrict power at higher rpm, I built a non cross flow, siamesed 292 Chevy 6 I did what we call a lump port which adds a chunk of aluminum right before the intake valve which was proven to gain power over a flat intake port
@@turkeyboyjh1 I have a friend that mastered carbon reading (heads off after every trip to the strip) - he became a voodoo engine builder whose engines got town down after every win and the tech guys would notice things he did and say, "if you fixed that, you'd go faster." Reading carbon is huge regarding combustion chamber. It's all about the wet flow. He never used a flow bench and saw no reason to use them. And yet he built the fastest engines. His all Chevy parts small and big blocks were amazing.
It's all a balancing act, swings and roundabouts. Air volume or can velocity ram a bit more in. Length of stack at certain RPMs. Great subject, many have spent many hours to achieve the optimum.
Velocity Porting is not to improve over all HP, it's to increase throttle response and torque DOWN LOW. Also It works the BEST mainly with FCR Style Carburetors to create more of a Vacuum on the back side of the Carburetor. Mostly used for Track Racing so you can get off the line and out of a burm faster. I actually Velocity Ported my own TRX450R head it make a Huge increase in throttle response and torque off the line as I stated just before this. I had each port job I would get a Base Line test. 1st Dyno Test (Stock Head --- 43HP at 7510 RPMS / 29FTLBS of Torque) 12:25 Air Fuel Ratio 2nd Dyno Test (Velocity Ported --- 48HP at 7238 RPMS / 38FTLBS of Torque) 12.10 Air Fuel Ratio 3rd Dyno Test (Port Opened Up --- 55HP at 8200 RPMS and 37FTLBS of Torque) 11.97 Air Fuel Ratio I read those off my Dyno Charts exactly how they were printed. From Racers Edge Arizona. I actually recently ported a new head that I'm going to test with +1mm Valves and the Valve Guides are sharpened and the port floor is un touched and exhaust ports polished with sharpened guides. Velocity porting does work. I was able to feel it when I would accelerate but had not very much top speed. Not for me unless I was racing on a Track. but I'm a lot more of a WOT person and to cruise on a long stretch rather then in and out of the throttle pumping it a lot.
TRX VLOGGER absolutley correct...velocity makes a big difference on a high performance street driven engine as well...throttle response--which you get from good velocity--- is fun...soggy response due to high flow and low velocity not so much fun...it's like a car with turbo lag but no turbo...thanks for posting....
Hi there. When you suggest putting the carb butterfly (6m 20s) at the same position as the epoxy filler you are over looking the fact that the flowing air would be trapped underneath the butterfly and cause massive turbulence and energy loss. However, the smoothed shape of the epoxy in the same position , if shaped correctly, will guide and funnel the moving air column into a faster moving one with little turbulence. Energy isn't really lost, it just gets converted into a faster moving slug of air which now has the ability with its extra inertia to supercharge the cylinder by drawing in extra air behind it, assuming the valve timing has a long enough port timing to allow it to do so and then closing at the right time to trap it.(By the way some engines do feel more powerful with a slightly closed throttle but this is simply because the main jet (fueling) is set too lean and the mixture at full bore is now too weak. This can easily be rectified) The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat. By making better use of the entire circumference of the valve seat the flow rate is improved as the valve can pass more air in any given time. Finally, another bonus is the higher velocity charge of the new port shape will swirl better as it emerges into the cylinder. Higher swirl speeds allows faster and more thorough combustion and less chance of detonation.
"When you suggest putting the carb butterfly" - just a butterfly - nothing to do with carbs. "Energy isn't really lost" What energy? What is this energy and where does it come from? "with its extra inertia to supercharge the cylinder by drawing in extra air behind it," - Dude, I'm sorry but you don't understand how air works or what inertia is. "The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat." - This is something you have just made up... "Higher swirl speeds allows faster and more thorough combustion and less chance of detonation." - and now you've made it clear you don't know what detonation is.
Modern bike ports are very, very good. There isn't much you can do to improve them. Use an OS intake valve and bore the seats to .9 of the OS valve OD. That will get volume up. On the other hand I have ported CB750 and GS 1100/1150 heads and used epoxy on the floor. They flow very well with very good velocity and have made great power through the RPM range. I use a Superflow 260 with a FlowCom and pull @ 10". The FlowCom is nice as it monitors velocity.
Yes, a good explanation of why putting a restriction in the port like that is a really badidea. Now, IF the entire port was simply straighter, (like pro stock drag racing ports are)then the port can and should be smaller... but for most engines that have to have a kinkin the port, it is much better to have the port larger to compensate for the turn, even ifit costs some speed. A lazy port can always be taken care of with better cam, but a too fast, plugged up port with too much turn causes the fuel to not follow the port shape verywell as it is much heavier than the air, leading to fuel separation and bad mixing withinthe cylinder, leading to power losses.
There is tune head porting. Depends on the application you are porting for, because if your goal is low end torque you dont need huge ports for large volumes of air/fuel mixture to enter the cylinder. You need smaller ports for more velocity to keep the air/fuel mixture in suspension to reach the combustion chamber at low speeds. Where at higher speeds you just need to get the air/fuel mixture in the combustion chamber as soon as possible, this where having larger ports within reason makes sense. Filling the combustion chamber with as much fuel/air mixture as possible is called volumetric efficiency. the goal depending on the application is to improve the volumetric efficiency at your applications engine RPM. To get the best volumetric efficiency at all rpm ranges, is to use two intake runners per a cylinder on the intake manifold, that has one larger shorter port, and one smaller but longer port. There is a valve that controls the flow through these ports for different engine requirements. Then on the cylinder head port is large for both low and high engine RPM needs.
it's all about Balance, too big a port makes for a lazy port and terrible acceleration. the goal would be to have as small a port as you can while maintaining flow #'s. In Motorsports Flow is great but Velocity is king! Port shape can also have a huge effect on flow. You make fun of the use of epoxy's well let me tell you, I have been building performance and racing engines for over 20 years I have used Epoxies(not JB Weld) in Intake ports many times and have never had it come loose. When using the proper epoxy and applied properly you would almost have to chisel it out of the port. I currently race a 10,000 RPM 4 cylinder, with ports that flow over 400cfm with Epoxy in the port, Don't Knock it until you've tried it.
If you can maintain flow #'s and increase velocity you will fill the cylinder better. which is essentially what it's all about. More air more fuel bigger Boom More Power.
The issues that you face with a too larger Port is loss of air velocity which equals a loss fuel atomisation which will cause loss in power so if you don’t atomise the fuel properly then you don’t get correct combustion of the fuel in the combustion chamber which equals a loss of power even if you have good injectors it still doesn’t atomise the fuel as efficiently as air velocity will so there’s a fine balance between having your ports to Big and having them too small
lol. So true.. I remember my old man who's built race cars forever though explained an example of this where velocity over volume worked with ford 351c V8's with 2v and 4v heads whereby the restriction was in the exhaust ports of the greater flowing 4v heads and you would make more power utilising smaller 2v heads with 4v exhaust valves and porting as the problem wasn't getting gases in but getting it out. This was for an improved production series but was the same for a tough street engine.
If I see "does it work", I'm not looking to watch a theoretical discussion...do it, dyno it and prove his method to be invalid if you're that strong on it. Talk is cheap, and that headline is "expensive."
AHAHAHA! Some chart grabbed from the internet with NO context or validation.. and... the HP doesn't even cross torque at 5250. HMMM. If hp = torque x RPM / 5250... then... every chart in the world must cross at exactly that point and no other. FAKE dyno sheet.
@@dirtygarageguy Ouch. People need to stop arguing on the internet and destroy some heads and post a video. PSST Engine masters has does this test and getting as much air in as possible with the least struggle is the best because the moving parts aren't trying to pull things in.
@@@aaronchadwick2682 … you mean because the moving parts ARE trying to pull things in; things in this case being air and fuel. If the pistons didn't create a vacuum how do you suppose those things would get in there?
@@chestrockwell8328 I mean't struggling to pull air and fuel in. r/corrections Good lord if you have a brain about engines you shouldn't need to use technical terms. If there a vacuum is present then don't create areas for there to be friction (velocity idiots) which causes loss of power
@J well golly gee... I wonder how it is possible to achieve 120+% volumetric efficiency in a normally aspirated engine ? I"m going to give you a hint: it has something to do with charge velocity and that old saying "an object in motion tends to stay in motion."
Wow, some interesting comments. I wont try and tell people how to port. I have my own ideas and have a home made flow bench. Im no expert. What i will do is mention all the things that need to be considered. Port size (volume), port floor shape (radius into the bowl), port roof, guide boss restriction and flow and turbulence. Area in the port at the guide boss. Area at the turn. Area in the ‘bowl’, shape of bowl to the valve seat, shrouding, shape of back of valve. Surface finish, blending in valve seats. People talk ‘velocity’, well yeah you need this for torque but what about velocity if the charge needs to turn a corner? Can you corner at an intersection at the same speed as you do in a straight line? The charge has to turn at the valve also. Simetrical ports or biased? The bigger the valve guide boss the more turbulence behind it? What is more important in a turn, the floor or roof? Do you know why? Knife edges (which i hate).
Thanks for taking the time to make this video to try to teach people what you know to be true. I see that this is an older video and has over 600 comments. I don't have time to read them all to see if you have answered my question, which is: Have you tried the "High Velocity Port" in practice and it didn't work or are you going strictly off your principles without hands-on experimentation? I met who turned out to be "Motoman" once. He passedme on one of his bikes while checking high-speed tunning. His bike went from WOT to nothing at 140+mph and he pulled over to an on ramp shoulder. I could hear him approaching me for quite a distance and sounded unlike any bike I have ever heard before. It was the most efficient air pump that I had ever heard. When he passed the noise changed... there was a distinct difference between the intake and exhaust notes. So when I saw him pull over I figured he either broke something or was one of the few people that I have seen checking a plug for WOT the right way and wanted to know what he had done to the bike. He was indeed checking his tune. We talked for a while and told me about his high velocity ports and we talked about racing, building engines and people who are so confident in their mainstream understanding and common practices that they will never step outside of the box ideas. We chuckled reminiscing about some of our experiences with people who got so defensive and obnoxious when confronted with an out-of-the-box idea. It's just hilarious to watch people spend so much time and energy to call your idea stupid and prove you wrong when they have never tried it. My father built competitive engines all my life. He taught me that building a competitive engine is about understanding the purpose of the engine, compromise, proper experimentation, and doing it better than everyone else. He was always learning. He would allow himself to think outside of the box because that's where progress is made. He had ties to a few of the best engineers and engine builders in the world. You would be surprised to know just how far outside the box those guys get. Volocity has always been more important than CFM. Big CFM doesn't count until you get at the top 25-30 percent of your rpm range. If you can keep the proper velocity up in the intake and exhaust and tune them with proper design, you have enough CFM flow at WOT and hit that sweet spot of compromise then you will ALWAYS be faster than the guy going for biggest CFM. The compromise is that if you give up some CFM you get more back with atomization, better scavenged cylinders for more fresh A/F mixture, cooler temps, much wider powerband, etc. I just don't understand why people get so upset about ideas to improve velocity to a greater degree than the standard accepted norm. Especially in 4 valve heads! I can understand more why in 2 valve heads. I'm not saying your wrong, I'm just asking if you have put your ego aside enough to actually try it? Just grab an old head you have laying around, do the math, do it right without sabotage, re-tune properly and make a video of how wrong he is with actual evidence. That's the video I was hoping to see.
"When he passed the noise changed... there was a distinct difference between the intake and exhaust notes." - That is called doppler shift, and nothing to do with intake or exhaust.... "I'm not saying your wrong, I'm just asking if you have put your ego aside enough to actually try it?" - Yes, and in the next 6 months I'll be proving it out. Also it's physics, not an opinion. Nothing to do with ego or anything related. There's something alreadyin your engine that does the same thing, it's called a throttle.... 3/4 throttle doesn't produce more power than WOT. "Volocity has always been more important than CFM." - 1) I'm sure you meant velocity 2) The speed of a flow isn't more important than CFM. That is crazy. Fuel volume per unit time is directly proportional to fuel and fuel per olume is directly related to power. "Big CFM doesn't count until you get at the top 25-30 percent of your rpm range." - That is utter bollocks.
Thank you for your reply and I look forward to you doing actual tests, comparisons and showing track numbers for evidence. "That is called doppler shift, and nothing to do with intake or exhaust...." -Anyone who drives on the highway much has has dozens and dozens of bikes wiz by and knows what doppler effect sounds like. Normally you don't even hear the bike until it passes you. His bike had a distinct intake noise to it. I had never heard a bike sound like that until that point. "Yes, and in the next 6 months I'll be proving it out. Also it's physics, not an opinion. Nothing to do with ego or anything related. There's something alreadyin your engine that does the same thing, it's called a throttle.... 3/4 throttle doesn't produce more power than WOT." -Great! I look forward to seeing the results! Yes, physics. The funny thing about physics is that there are so many theories and not many laws. Plus there is a huge difference in theoretical physics and actual physics. And if you really expect anyone with any knowledge of physics to buy that a butterfly valve is anything like the shape of the intake runner then you need to talk to a physicist to tell you just how wrong your thinking is. Again, I'm not saying that your wrong that high velocity porting in the way Motoman shows is not conducive to making more power, I'm just saying that if your holding a butterfly throttle up in comparison to any kind of intake runner alteration then it just shows me that your lack of understanding is far worse than I originally thought. -"1) I'm sure you meant velocity -Yes. I meant "vElocity". Like I correcly spelled before and after that. It's called a typo. You see, when you are typing on a small touch screen device sometimes another finger will tap the screen and cause a letter to be typed that you didn't mean to type. But thank you for taking the time to point that out. Your so smart. "2) The speed of a flow isn't more important than CFM. That is crazy. Fuel volume per unit time is directly proportional to fuel and fuel per olume is directly related to power." I agree and disagree. If you have a port that can provide 300cfm just do to the total area it doesn't mean that it is effective enough to fill a combustion chamber efficiently. In addition to that the fuel is much more likely to fall out of suspension creating poor atomization. Maybe saying proper velocity is more critical to an efficient engine than most CFM you can flow. If you still disagree then we will just agree to disagree. "Big CFM doesn't count until you get at the top 25-30 percent of your rpm range." - That is utter bollocks." -In the vast majority of engine build WITH ACTUAL PROOF AND DATA, if you take a well designed and efficient engine and bore the intake out to flow the biggest numbers it shows both in practical on track racing and on the dyno that you loose torque and horsepower in the low to mid range and only start to be more efficient in the upper 30% of the rpm range. If you are building an engine that produces peak efficiency at only the top of the rpm range then the compromise of sacrificing velocity for biggest CFM will be of benefit in some cases. However, keeping velocity is still important. So I stand by my statement.
Don't think you can hide... pressure is N/mm^2 or Pascals if you wanna be posh. So we know what mm^2 is, that's an area, so what is the N? What two properties define N?
AGREE, put ALL the air and fuel that you can even if you have to pushhh it inside!!! then make the mixture the most perfect possible and HELLO 200% POWAAAAH
It’s not the same for every single engine, for example, the ports on a 351 Cleveland V8 are too big in standard form but work well with a more aggressive cam. The 351 Windsor has smaller ports which are suitable to the stock cam, not as beneficial with a more aggressive cam. Velocity and flow are as important as each other, it’s not a one size fits all, it’s the complete combination from compression ratio, port design, cam profile, valve sizes etc. Bigger is not always better
way I see it, I trust manufacturers to calc out this shit to perfection. that said, if I'm working on my own machine, I'll polish out all the casting shizz for a clean port. not because it does any good- but because I fucking like it that way.
geogineer Thats what a old engine tuner told me. Get the inlet and outlet ports as smooth as possible. From the factory they ate a bit rough to say the least.
They don't... Perhaps in F1, they put som effort to it, and look at those ports... their smallest cross section is actually quite small compared to valve size vs. a normal production engine, and the venturi-style port has a good diffuser section before the valve and seat insert area. As there is none to little pressure recovery to be had in the very flat combustion chamber... Typically the port mCSA of a F1 engine is roughly 75% of actual usable valve curtain area. Your typical OEM car cylinder head often has it the other way round... Port mCSA is often larger ( often 125%) of valve curtain area... Production engines (other than bikes) as a whole seldom moves above 100hp/liter without the aid of forced induction... their ports flow just "good enough" to get the job done and is mostly configured towards meeting emmisions, and quick/easy casting and manufacturing. And with regards to "polishing" a intake port... if your engine got anything else than direct injection you loose power with "shiny" ports... If you want a port injected engine that has poor start and idle, and low to mid-range power, whithout having any added benefit at high rpm WOT, In addition to be more prown to end-gas detonation... by all means... go ahead and polish the living shit out of it... It's not my loss :)
Njål Nilssen you are completely right: the port in production engines is bigger then what the curtain area flows. In doing this the valve seat controls the amount of air entering the cylinder. Not the incosistent cast port. Therefore a smaller port works !!!!!!!!
ok , i haven't got a clew on how did the epoxy port filling come up or the arguments that were being used, but after a while it´s just too much, so let´s get some things clear: 1-the biggest port possible" open head bla bla" IT´S NOT THE BEST OPTION, with such port you would only be able to achive a maximum 100% VE (cylinder volume at atmosferic pressure), a well designed head can actually achieve well over 100%, get the f20c for example it gets 110% VE from 6500-7500 rpm. 2-a well designed port will create an "air ram" due to the air mass momentum when the piston is at bdc and the intake valve is still open, explaining point 1. 3-epoxy , or any other type of filling, can be beneficial if for example you want to straighten a port and have to remove alot of material but still want a reduced port volume so point 2 can be achieved! 4-when you close the throttle you only increase air speed near the butterfly valve and not the entire port like you need for it to work! 5-if you have an engine that isn´t direct injection the fuel atomization will be better with a faster moving air charge. greetings, hope you give it a thought
They main issue is mistuned camshaft timing - intake manifold length, exhaust etc. pp. -> less pressure drop is always a good thing - but you need to get you intake/exhaust timings tuned to this. At carb engines a massive reduced pressure drop is an issue like on old V8 engines, the vacuum is too low to keep the carbs proper working. So you run into different issues (slider doesn't open maximum for example or slider spring is too weak and bouncy), you have to understand the impacts. And yes big does not mean ideal .
The way how this is explained is exactly how my fluid mechanics lecturer explained the rate of flow through a tube. You want more flow through a tube, get a bigger tube. Adding shapes to an otherwise cylindrical tube will create localised areas of turbulent air flow and hence reduce the overall Reynolds number ie the velocity of air flow. This video is the best explanation I have seen explaining fluid motion in very simple terms. Well done.
I guess the point they got wrong was mistaking lateral velocity of the air for Volume stream i. e. Flow. Pressure, Flow and resistance are interlocked: Pressure is equal to Flow times Resistance. But it is important to note where these Values are measured. The Pressure in this formula is the Pressure needed to create that flow through the restriction. It is not the Pressure of the fluid after passing the restriction. If you keep the flow constant and add a restriction, then the Velocity of the air DURING THAT RESTRICTION will increase, as well as the Pressure in front of the restriction needed to keep the flow constant. This will not give you more Horsepower though, because the limiting factor for HP is how much volume of air you can squeeze into the Cylinder to burn more fuel to get more power. So, you want to maximise Flow. And to do that you can either increase Pressure (crank up your boost or reduce the volume of the intake by making it SHORTER, not NARROWER because that would increase restriction) or decrease Restriction. These rules are true, but keep in mind that they are for static pressure and constant flow, which is not the case during the full engine cycle, only holding true for the explicit intake/exhaust stroke. But the effects of the pulsating pressures and flows in the intake runner do not completely invert the rules stated above. My guess is, that someone really mistook flow for velocity and tried to maximise that, which would make narrowing down the intake make sense. Unfortunately that is not true. The only point where i think narrower channels would be viable is, when the intake volume is so big, that the Turbo/Supercharger/ambient pressure cannot replenish air and Pressure in the manifold fast enough (analouge to a too big voluminous intercooler increasing turbo lag).
The guy who said that restricting the port size to increase flow is off his nut. Ports are by their very nature funnels. The limiting diameter is the size of the opening that the valve covers when closed. The shortest distance between two points is a straight line except in the case of guns. They have spiralled tubes and that spiral gives the bullet rotational momentum to stabilize the bullet after discharging from the barrel. The length of the barrel and the pitch of the rifle spiral determines the final velocity along with the powder charge and make-up of the projectile etcetera. In short, the longer the barrel the faster the terminal speed of the projectile exiting that gun barrel. Enlarging ports is only a part of cramming more air into a combustion chamber. The main goal is to straighten out that port and runner to allow the air to enter/exit as quickly and smoothly as possible. Spiralling that runner could potentially allow a larger volume of air into that port because of centrifugal force acting on that column of air somewhat similar to a bullet. Dimpling the runner, similar to golfball dimples, could also be another way of stabilizing that column of air. Reducing the vortices that would build up as air flows through a funnel tube is the other consideration. Diffusing striations, similar to the rear undercarriage of racecars, would also reduce vortices in the runner. The fewer the vortices the straighter the path of air. Slightly dished in valve faces could be employed to give a negative vortex in the combustion chamber sucking in more than otherwise would be possible. Using exhaust scavenging is another way to suck in more air. The mere fact that the size of the valve restricts the flow is the ultimate determiner of air velocity. Squeezing a large volume into a much smaller volume speeds up that air mass. That was quantified by Mr. Bernouli and Mr. Venturi. I hope that I haven't made an asshat out of myself. I haven't studied physics for many years and I haven't worked on large shipborne diesel engines for about as long. Thanks for the segment.
This was well done for a subject that people act as if its black magic, well explained with simple and understandable analogies, good stuff. A great sequel to this would be intake plenum size!
Well explained again Matt. Doesn't matter. Some people will never understand. Same kind of people that think they can use their car's engine driven alternator to crack water into Hydrogen and Oxygen and get better fuel mileage. Or they think because they saw a guy with an electric supercharger making boost on youtube then electric superchargers must be a thing. The only time velocity matters is at the venturi of a carburetor. No one racing bikes, or even cars for that matter, is going to be using a carburetor unless it's a class rule. Even then, they are not at idle/part throttle most of the time. So it still doesn't matter. Mass flow makes power. Small ports ruin flow. Thus they ruin power. You can white board all the diagrams in the world and motodouche is never going to change his mind.
The Workshop you make great videos :). thanks a lot man.... could you pleace make a video where you explain how the 2 stroke direktinjektion engine like brp gets a ignitable mixture during the upstroke? i mean it works, but how it works in this short amount of time and the shit air flow of a 2 stroke. please keep up your good work. best regards from germany ^^
We owe it to gas gas for dirt bike injection. anyone who says ktm did efi on 2 strokes is full of shit. Gas Gas brought efi to the 4 stroke dirt bike world, and then, they brought it to the 2 stroke world. some of their current 2 stroke trials bikes have efi
There are some odd conclusions made here. You have several logical fallacies in your argument against a "high velocity" port. Perhaps we need to be talking about Volumetric Efficiency. Yes, you can achieve better volumetric efficiency with a PROPERLY DESIGNED port that might be smaller in size and volume than the original stock port. By adding material to a port we are not trying to create a restriction, we are attempting to remove a dead air zone where little air flow is happening. This is port design 101. By your logic "bigger is better" and we know that simply is not true. Porting is a science and a huge industry. The porting industry exists because ports are not perfect. The best ports are not the biggest. The best ports don't just flow the most CFM. They need to be able to flow is at as high a velocity as possible to raise the VE beyond 100%. Sometimes we need to remove material from an area of the port, sometimes we need to smooth areas, sometimes we need to add material. Usually all three if the OEM port was not well designed. A case in point is a motorcyle port I changed to be smaller and better designed than the OEM port. The new port was MUCH smaller but we picked up substantial flow. On the dyno we increased a 1000cc motorcycle's power by 15HP. This is with no compression or cam changes.
@@robingrantgast2065 It's known as "inertial supercharging", see here: en.wikipedia.org/wiki/Volumetric_efficiency en.wikipedia.org/wiki/Inertial_supercharging_effect
@J You need to review the basics if that's what they are telling you. Please educate yourself and stop relying on whatever you are calling common sense. If you are interested i'd recommend books Harold Bettes , David Vizard and John Baechtel. You are full of crap and this is coming from a person who actually owns a flowbench and does dyno testing every tuesday (engine) and wednesday (chassis)
Great video! 9 out of 10 for science content. The pressure doesn't drop when you restrict but let's let that slide. What I think these guys are really doing is just smoothing out the casting of the runner on the cheap. But believe it or not first time I have heard of this. We always ported heads by removing material and smoothing. You do lose some low-end torque but gain HP. Also great work on fluid momentum. It plays a lot bigger role than most understand. An engine running at 6000 RPM is moving air around 270MPH in the runners.
There are many points in this video I disagree with, but literally that's a very basic law of physics. As speed of a fluid increases, it's pressure decreases. It's how venturies, chimneys, and aircraft wings work. Coming from an aircraft mechanic specializing in environmental systems, but really this is high school science 101.
@@dsan94 You may be confused as to the which side of the restriction you are thinking of. Post restriction the pressure will be lower. In front of the restriction the pressure will rise (or in the case of vacuum decrease).
The way I see it, you have atmospheric pressure outside the throttle body and dropping pressure in the cylinder (as the piston falls). The tendency of atmosphere to equalize itself is where the molecule movement moves the outside air down the port toward the lower pressure in the cylinder. The absolute BEST that could happen outside of forced induction is a 100% equalization of cylinder pressure to atmospheric pressure. We know that's not possible. Air has mass, and mass in motion will have momentum. Engine builders who want to tune a given engine to have greater lower end torque typically employ several things to achieve that. One of which is smaller port sizes per a given cylinder displacement. That achieves higher flow velocity through the port at lower engine RPM. Among other things, this creates faster cylinder filling, greater air mass momentum, at lower RPM and increases torque at lower RPM. Of course these types of setups result in limited upper RPM power due to less efficient flow at high RPM. The perfect theoretical engine would be one that has infinitely variable port size, infinitely variable intake runner length, infinitely variable valve timing, infinitely variable valve lift, infinitely variable compression ratio, and infinitely variable exhaust runner diameter. Wouldn't that be some engine!
A NASCAR Combustion engineer once told me: "The best port would be a straight port from the beginning to the end of the port. If you can see the exit of the port from the entrance, you're doing better than if you can't." Also, there are studies about "optimum" intake velocities of air, but these "optimum" velocities are only applicable for certain ranges of rpm. It's all about what band of RPM you're designing a head for.
This is a super interesting subject! I’ve heard really well known high performance engine builders talk about how equations and modeling only get you so far (roughly in the ballpark) when trying to increase performance and it takes lots of experimenting and dyno testing to truly arrive at a winning design due to the many interrelated variables that effect engine performance. (It’d be cool though if people could talk about their ideas without talking down to people with different ideas or understandings.) When it comes to intake paths not all restrictions are the same. Your analogy of pushing people through double doors isn’t completely comparable due to the Bernoulli principle, which is roughly the idea that as a fluid moves through a pipe past a restricted area (think of the restriction being a curved surface like an airplane wing and not like a flat butterfly valve) that fluid speeds up around the restriction which also causes the pressure of the fluid to drop at the restriction. People being pushed through double doors wouldn’t be subject to the effects of the Bernoulli principal like a fluid would. So I could see how someone could think that using the effects of the Bernoulli principle by slightly decreasing the diameter of the intake through the use of a curved restriction would increase the velocity of the air thereby increasing the amount of air getting into the combustion chamber as it rushes past a given size opening/intake valve, however from a physics standpoint, you can only get as much air into the combustion chamber as you get into the intake first which agrees with what you were saying in the video to a point. Although, increasing the speed of the air entering the combustion chamber may cause the fuel and air charge to be more thoroughly mixed which would allow for a more complete combustion of the fuel air mixture which would increase hp. In addition to the complexities of intake geometry, I know acoustics/harmonics have an impact on how the air/fuel moves into and out of the combustion chamber which is another whole level of complexity. Also it’s has been proven that texture is also important to a degree and having a slightly rough texture on the intake surfaces does allow for better performance as opposed to having a mirrored finish do to creating a smaller boundary layer of air close to the surface of the intake thereby creating less overall drag. Anyway, I think it’s badass subject and I’m sure no engine builder is ever done learning. ✊🤙
In all actuality yes "high velocity" porting can cause resonance to occur and create more power, but I think motodouche doesn't understand the actual science once again. The power gains will be miniscule and at such a tiny rpm window that its not even valid! Plus as matt explained rather humorously, it will decrease overall topend power and power under the curve. People who poorly understand something, take 2% of the facts and draw a incorrect conclusion are the bloody worst, sod off motodouche lol
I don't know who this motorman you are talking about is... But I think he has missunderstood the consept if he does it the way like you draw it here..., it's too close to the valve, the port should have been straighten out, the bowl filled slightly in the roof after the valve stem and It has nothing to do with resonance, but more so about increasing velocity WITHOUT restricting flow. Closing a throttle a little is a pure restriction, because it has a very poor pressure recovery behind it, so all it does is creat a restriction as there is no working diffusor behind it to convert velocity back to pressure. Most of the instances where "velocity-porting" (stupid name really) works are on engines with combustion chambers that give a poor pressure recovery AFTER the valve. like most 4 valve head and especially on high compression MC-style heads with a very flat pentroof. Usually the valve window it self is the main restriction, thus shrinking the port in the correct manner (as it's usually overkill compared to the actual flow of the valves) you gain both higher velocity and flow due to better pressure recovery due to the formation of a proper diffuser (aka the means of converting velocity to pressure) the higher velocity you achive without restricting anything gives you a better "ram" effect due to higher inertial forces, and 120+ % trapped VE is common on NA engines. And believe me... not all OEM engineers has got the ports right in a long shot... sometimes perhaps with regards to emissions, and emissions only, but what performance goes, not by far...
I work with hydraulics on automotive and yes motorcycle lifts. The orifice restricts the volume and increases pressure. In this case, the pressure increase will be lost filling the volume on the other side of the orifice. The old trick of trying blow a ball of tissue into a soda bottle will also be a factor as well.
Good point on vvt & similar. Timing of the valves & size. When port shrinking works it's apparently a quick fix for excessive duration. Or just bad timing.
@theworkshop Do you think you would see better vol. Efficiency at lower RPM range with this nozzle idea? I agree at high RPM you want that baby wide open. The reason I bring this up is I was running some engine simulations with 2 valve vs 4 valve and the 2 valve had better vol. Efficiency at lower RPM. That was a head scratcher for me but concluded that it was because of higher velocities...
Hi Matt, your going to have to do another video on direct injection porting. This is totally different, we use diverter vanes & other ways to not blow the fuel into the cylinder wall. Things changed in a big way when we got to direct injection. The old ways just don't work. Keep up the good work..
There are those that never will understand an engine. And there are those that will understand them. Most likely the latter is the majority unfortunately...
or if you want to turn around the other way you could use a Shop-Vac as an example take your normal to inch hose and modify it to a 1 foot opening completely sealed no leaks will probably not even be able to suck up a leaf or a piece of grass now when you reduce it back to the original 2 in diameter size hose it has plenty of suction for that size displacement pump whatever you would like to call it ... there is always a certain size for the correct flow volume velocity pressure however you like to put it for different applications bigger is not always better
When you get to the limit of the flow of the valve slow moving air will not help you, high speed air will however as well higher pressure. The valve is only fully open for a very small time but its opening and closing time is a lot longer. This is why we want fast moving air to actually hold some pressure behind the valve waiting for it to open. Air is quite heavy and getting it up to speed takes a while and so we want to keep it moving and not to lose momentum
Ford solved this in the 1990's by adding intake manifold runner controls (IMRC) that block the 2nd intake port in their 4V "b" heads (most commonly associated with the Mustang Cobra), opening the 2nd port after 3250rpm. They just weren't getting enough torque at low RPMs without this and emissions were simultaneously below requirements. The down side (beside the extra mechanical parts) was that the secondary valves stems built up with carbon to the point the valve stem was easily double the diameter as it passes through the port due to lack of fuel to keep them clean in daily driving. I know because I am rebuilding one.
A few people on here would do well to read the works of David Vizard, a man who spent his whole life on a flowbench and dynomometer. What he doesn't know about porting etc.. (That's a serious one for a change!)
Mate you have no idea... if you close off the port at the throttle body you are restricting the air flow. if the port gets smaller as it gets closer to the valve the airflow will speed up.
I don't pretend to know all that stuff... you should learn the basics before loosing yourself in all the other stuff that way you would get less negative comments.Learn to take your mistakes on the chin or understand the stuff you are talking about first.
@@dougharvey9766 actually he's pretty much spot on... it's something motorcycle race engine builders focus on... a restrictor plate on the intake is used to keep HP figures down... same with race car engines if the car goes above HP limits they install a restrictor plate to reduce the amount of air getting into the engine... all this does is amplifies this practice... if you blank off 10% of each port on a 4 cylinder engine you are losing 40% of usable airflow... however, if you look at the ports on a factory turbo application they are shaped in such a way because the air has no way of returning back to the intake because it is being "forced" into the cylinder...
The only way to add pressure to any engine is to force the air into the cylinder while defeating the atmospheric pressure. Please check your local elevation for that info. One thing to mention when it comes to air, when restricted under pressure it will expand on the other side of the orifice: causing it to become colder allowing the air to be dense. That will make power.
I agree with you that this idea doesn't work, except possibly over a very narrow rev range. I will add, however that if an engine at full throttle seems to go a little faster with the throttle slightly closed, it needs the main jet to be replaced by one which is slightly larger, as the aforementioned condition indicates a weak mixture at wide open throttle (or WOT).
I think what Motoman was trying to do is improve the short turn of the port, I think it's along the lines of applying Bernoulli's principle, the same way flow is improved at the valve seats at low lift through various seat angles
When you have a chance, search "Toyota dynamic force engine". If their comparison images are in any way accurate, they pretty much block half of the valve face with a "ramp" in the port and concentrate the flow on the upper half.
Yes for low speed - to increase the port velocity at low flow rates - this increases low end torque - but it increases in port cross-section when the revs increase. On motorcycles who wants to sit at low revs? Just drop to a lower gear.
@@dirtygarageguy A port being larger does not automatically mean it's efficient. Often a smaller, but efficiently designed port will start flowing sooner than a big one, but keep flowing where the big one finally gets going. An example: This FSAE team used a novel additive manufacturing process to produce an idealized intake manifold that allowed a CBR600RR engine to reach it's red line despite breathing through a mandated 20mm restricter. 3dprint(dot)com/201534/3d-printed-intake-manifold-carbon/
The the venturi should be set up in the area right before the valve seat so a high pressure zone is created right before the cylinder. There is such a thing as too big a port and it comes down to the loss of fuel atomization at the low end due to lack of air/fuel charge velocity. Toyota and GM used swirl ports on some of thier engines back in the 70s and 80s to keep good atomization and emissions down.
"Toyota and GM used swirl ports on some of thier engines back in the 70s and 80s to keep good atomization and emissions down." - because of the use of either carbs or single point injection - with multipoing injection they stopped doing this. The reason is due to flow seperation around a radius.
Maybe this point has already been mentioned in these comments.. To say that the 'biggest port' possible will flow the most, or that 'no port is too big' is not accurate. The limitation in most cases is the valve diameter (i.e. The area around the valve seat). Given that restriction.. the port that would flow best into that restricted area is not the largest port, but the port with the size to optimise velocity and flow.
In other words.. Choosing to place a restriction before another restriction (that you had no choice in.). can make sense. If the restriction you placed is less restrictive than the valve seat area there should be no issue. A port can easily be too big for the valve seat area (restriction).
It was common to raise the port floor on early R6 s look at tony homes and other iom sidecar engine builders .. I would give 2-3 hp on the 99 600's just saying...?
No one is talking about temp. Doesnt thermal dynamics have the biggest part of what we are discussing . You have a cool air charge trying to be forced into a hot chamber. ie higher pressure, yes the piston is in the charge stroke but the temp is fighting that action. The pistons vacuum capability decreases exponentially with rpm. so isnt speed of the charge the answer. IDK just thinking out load
You haven´t ported many heads haven´t you? In short: Motomans ideas are not wrong, just a bit or a big bit excessive. When portiing a head you want a 'small' area(venturi) in the runner to add speed to incoming air. This area needs to be at a certain distance from the valve, to tune it for a certain rpm range. Your example of lifting the head and dropping a shitload of air in doesn´t increase VE above 100%(not making any big power numbers) Racing engines got about roughly 120% VE, experimental engines have reached up against 130%. How to do that? Well you add speed to air to get high inertia of airflow(but you cant go over mach1). This can load cylinder more than 100%, creating a positve pressure at the valve. This 'venturi' needs to be carfully shaped(certain area of valvediam) and in correct place to let air after venturi diffuse and get higher pressure again before reaching the valve. If this is succesful you can this way overfill the cylinder and get above 100% VE. Study on..
well.. As i have seen a lot of your clips and many of them are some kind of just mumbo jumbo. put on a cool shirt and draw some stuff on a whiteboard doesnt make you mr knowitall. it might feel like it. question though: did you ever read my first sentence in my first message? a advice for the future: be careful what you are preaching people might belive you. advice two: take a couple of hours study on shaping ports on speedtalk forum. then get back to me. study on!
it's like a bend in a river isn't it? the water on the inside of the bend slows down, and adding material will just increase the angle of the bend and slow the flow even more
You want to get the A/R of the port to be just right, so its essentially non restricting but still tight enough so that the air hits the closed valve with a velocity that causes the air mass to compress until the valve opens again. This way the head will suck in denser air and thus make more power. Its just like the way that header pipes need to have the right interior diameter otherwise it will be too restrictive or you wont get any scavenging at all.
Almost every engine I've seen in BSB & BSS is running high velocity ports. Mainly fillling the ceiling to alleviate sharpening the bend. I've personally gained large chunks of power and rideability filling ports on various engines, and know many other tuners who have too - In some fairly interesting fashions. Don't knock it until you try it!
My though is that this is a good idea, only if there is variances in the area of the port in different parts of the port. If the short side of the port radius is larger that the rest of the port you will loose port velocity. But it may not be necessary to fill in the entire area. The port should be flowed as you progressively fill it in.
why didn't you just use the carbarator example....you know the ventura principle. or is that too much for you...........what's the difference between you and a rotorary engine?
They've already extensively tested and proven the concept of port velocity relative to torque. Port shape directly influences velocity, which directly influences torque which directly influences your final hp numbers. As far as high rpm hp, yes you are correct, the shortest, biggest, least restricted port is better, until you become limited by piston speed. The problem is, people don't redline it everywhere they go, at all speeds. You'll need torque lower in the rpm band to move the loads. And so ports are shaped and sized according to the application. Smaller, higher velocity ports perform better down low, but they will eventually become limited by how much cfm they can flow, which will limit your hp at higher rpm. And you can't just hog em out because everything between idle and wot will be missing, as far as power is concerned, turning your money pit into a dog. Just size and shape your runners relative to your target powerband and you'll be fine. Until we get infinitely variable intake runners, that is. Or just use an electric motor.
What people talking about velocity or mean port velocity is all true to a point.there are so many variables in port designs. It's a inch below and above the seat that's where 65 percent of the flow is 25 percent around short turn and vavle guide and the runner 15 percent. a well designed port should extend a inch or 2 into your intake runner .flow brench and mathematical jumbo will help in performance gains . another place not to over looked is overlap just when piston is parked a tdc its overlap that's helping incoming charge to be drawn in.but on saying that a longer stroke engine is parked at tdc longer then a short stroke engine .Cam, angles cut into seat and valves crank angle and it doesn't stop as I port heads and I'll share this variables that's what it's about
Port area is good for mass flow up to a point, but accurate carb metering needs to have a strong vacuum signal so port velocity is important too - its about getting the compromise for the intended use and rider preference.
Matt, he has seen something that the drag race guys do use. They don't use the epoxy near the valve. They use it near the beginning of the port when using a single plane intake feeding all the ports. What they are finding is that the floor of the port is not being utilized very well. What they are doing is raising the port. I am 100% serious. This is a wide open throttle situation where max power over the largest curve possible. What the guy I talked to said (he built pro stock bike heads..probably 10 years ago) was, The engine can not utilize the port WOT at the RPM range we run. The air velocity is so high, the bottom of the port has a boundry layer that is influencing the flow in a negative way. They raise the port floor and it comes to life....mostly because of the valve actuation, time it takes to open, time it is open, and time it is closing. I will send you some pictures of some V8 stuff he did and the improvements it made. That said, this work is no where near the valve like you have drawn.
Imagine the top of the port as you have drawn it but the bottom floor is lower than where the curve down to the valve is. So, the transition to the valve opening is by far and away the restriction at WOT and with the valve at max lift. All they are doing is raising the floor to attempt to minimize the transition. That transition is key because flow at that area needs to be streamlined as much as possible because air particle momentum can influence boundry layers and further minimize flow potential. That said, everything I have seen is on 2 valve per cylinder heads.
Toyota back in the eighties had TVIS. You had monster ports, with two intake runners per port. There was a TVIS plate between the head and intake manifold which contained butterflies that blocked off one intake runner per cylinder up to (I think 2800rpm). Closing off one of the intake runners at low rpm increased port velocity and the whole arrangement also meant that air fuel atomized real well in the combustion chamber. When the engine revved beyond 2800 rpm the butterflies would open in the secondary intake runners and more air fuel could get in with an adequate port velocity. Motorman is right that ports have gotten too big, and this is at the expense of low end power. You are right that ports need to be large to support flows for decent power, but this comes at the expense of low rpm port velocity. It depends upon a customers requirements, whether they want high rpm or low down zippiness.
Secondary butterflies in a motorbike engine have fuck all to do with port flow. The secondary butterfly is ecu controlled so a hamfisted twat doesn't bog the motor when accelerating. Works in a way like cv type carbs. As for adding epoxy to reshape the port (raise the floor) of it didn't work Hrc wouldn't have done it to their works bikes.rvf750 comes to mind.They use epoxy as the rules state they can't weld material to reshape them. Ever heard of v&m racing they made tuned the rvf for Honda UK. And guess what they used epoxy to help reshape the ports. One huge error in your theory is not thinking of the pressure wave of the valve closing . In a big port can slow or even stall the in coming charged air. Where as high velocity ports (epoxied) will effectivly negate this issue. Go do some proper research into this . Ask fw developments they do it all the time .
It sounds like to me just start the air intake out as wide as possible within practicality and gradually narrow it down to the entrance of the intake manifold for the best combo of air flow and air velocity.
Independent throttle body with long strait intake it will stack the air and create a creator force against the valves. However, you need a long and as straight as possible intake pipe so positive pressure is still traveling to the heads. If it reverses direction your screwed. Look to steam injectors for the concept of velocity.
You don't undestand. reshaping a port is not closing a throttle. reducing a section with a good aerodynamic profile allow to increase air speed ,so ability for air to go deeper in the cylinder,pulling more air behind itself. closing a throttle plate create a lot of turbulences behind it ,reshaping a port do not,but oinly changes air speed. air is compressible,It's not a flow of water.... It's a basic aerodynamic concepts . Look at Bernoulli principles, Venturi principles etc... You have not a real idea of what you talk about by lack of knowledge. With your idea of air flow, planes and birds couldn't fly...
Poor choice of words there - elastic is generally described as 1 of 2 things - Elastic deformation when a material 'springs' back to its former shape/profile. The region before yield an plastic deformation begins. or Linear elasticity - based on hooks law etc. These are all solid elastic transformations. Liquids and gases do neither, because liquids and gases do not form crystaline structures that are bound through the metallic or covelant bonding.
Yeah, Try to explain yourself in technical french without looking at google like you did to get two definitions,and then you will can open your mouth (in french of course) You understood me : air is a fluid,compressible, contrary to a liquid (wich is too ,but just a little) You can push or pull a compressible fluid through a reduced section without loss of flow mass ,simply because its speed (flow on time) is good enough. It's exactly what you do in an engine head when well designed. Formula 1 cars did use that during the naturally aspirated era and had a huge volumetric efficiency,they were even able to have positive pressure in the intake when the valve was closing. The fact that air speed is appropriate and compressible.
That guy IS doing it wrong for sure. He probably does have gains somewhere, probably at lower RPMs... but, unlike a system designed to keep the velocity up like a Toyota 4AGE's T-VIS, he cannot remove the restriction for higher RPMs (not counting the J.B. Weld breaking away unintentionally.) A dyno plot would probably show both the claimed gain and the loss elsewhere. The T-VIS uses a throttle like valve to close off one intake runner to each cylinder, and over 4500 rpms or so it opens them up and you feel all the fury the Japanese could put into a 1.6l 4 cyl. in the 80's. It's one reason why the NA Toyota AE86s and MR2s were great.
The ONLY place that I could conceive of this having any benefit at all would be in NASCAR restrictor plate racing but even then you would not be reducing the entrance size but just matching the size of the "plate" so your flow does not bunch up along the hard edge of the restrictor plate.
love the explanation... funny side note i tell people who ask me how to make more power " the difference between your Hemi and Top fuel Hemi,,, more air than most jet engines suck in, Fuel that contains air because why not and spark plugs that draw more amps than your friends speakers in his trunk... why all this you might ask well,,, it's like they say there is no replacement for displacement how ever it is the air they are talking about not the engine size displacement" that is normally when i get the what look so i dumb it up. get more air in the cylinder and follow suit with every thing else more air more fuel more spark and timing if you dare.
i have run epoxy ports in a drag bike for nearly 10 years and it is considerably faster than similar spec engines at ALL engine speeds.It was in the worlds fastest and quickest bikes right through the 90s on any serious drag strip.Each one of youre seemingly reasoned arguments had ignored the reasons that make this work,although you are right on the point that this is about volumetric efficiency and massively affected by cam timing but youre just quoting it ,3.05 proves you just dont really understand.There is so much that you have proved here that you dont know that the simpleist thing i can say is just because you ignore something wont stop it from happening.This HAS been proved at national level in races to work no matter how much it makes you swear.I dont see it working with modern down draught Ports tho and also doubt you have ever sucesfully ported many heads(ye gads please dont)or you wouldnt only understand half of the picture.You have surprised me opening u a port like you describe will KILL any decently designed head,.read what others have said here and you may lern something,youre half way there,5 out of ten
I have been searching for answers on this subject for some time. I also work in the pump and valve industry. I can't see how you think restricting the port size will not increase velocity - it does and how you think that pressure will drop - it doesen't. I work with pinch valves, in principle a rubber tube inside a casting that can be closed by compressing external pinch bars. The most common problem for high wear rates is when people try to use a control valve incorrectly selected so the valve is so tightly closed it has extreme velocity through the aperture and very high inlet pressure. Building classic race engines as well, I would not put anything on an inlet tract that could be sucked into one of my engines. Great subject this but there so much conflicting information, my engines are high compression, twin cylinder, air cooled, four valves per cylinder, DOHC, ceramic coated pistons, competition cams, adjustable valve timing, still running on high octane petrol, not gone the race fuel route yet, I am convinced that there is more power to be had from the engine and its in the head
"I can't see how you think restricting the port size will not increase velocity - it does and how you think that pressure will drop - it doesen't. " - Velocities do increase, but the pressure drops - therefore. What matters here is time. Valves are only open for a finite time due to valve timing. If you increase the velocity the pressure drops for the same mass-flow rate. The issue is the pressure drop vs time. "The most common problem for high wear rates is when people try to use a control valve incorrectly selected so the valve is so tightly closed it has extreme velocity through the aperture and very high inlet pressure." - Inlet pressure is the key here not mean pressure.
Hey mate, dunno if it's the right question to ask on this vid, but it's in relation to tumble, if I created (in an ideal world) a flow from air filter to valve/combustion chamber, that had 10% (arbitrary number) more flow than needed, then created obstacles (Also arbitrary) to the tune of that 10% (gauged by a flow bench) to create tumble, would that be beneficial to performance if done correctly? Or is it just better to have straight flow for the amount needed. If it helps this question is in regards to an across the rpm range tune, over a peak window of rpm tune. Thanks in advance mate.
Great question and I think I get what you mean. So tumble is called turbulance - which ever way you wanna cut it it's like this... Turbulance is great for fuel mixing Turbulance is shit for mass air flow. This is what injectors are for. The Z900 I have now has 12 pintle holes in each injector. This increases atomization, which reduces the size of fuel droplets. Why would you want that? The smaller a sphere the greater the surface area to volume ratio. In other words - the surface area increases for the same volume. Why does surface area matter? Because this is where vaporisation happens.
With the vacuum of the piston sucking, still the chamber will only allow as much air to come in as it's volume will allow. The orifice of the intake is tiny compared to the orifice of the cylinder. Why restrict it more?
At some point you have to test your theory that it doesn’t work, you’ll learn something . do you think the engineers in formula one test their theories?
I think their missing the point.... F1 cars. NASCAR and high performance Motorcycles use closed Air Boxes. "This is what increases air velocity" and removes back pressure. One reason they dimple the head surface and ports. They want to keep the air flow from hugging the walls. This also promotes better fuel economy. As today fuel economy means more laps per tank of fuel....And if you can go 3-4 laps more then your competitor per tank. That is equal to seconds in lead times over the course of the race...It means shit on the street...
Like hell you can't... It's why they run water injection. It cools the air charge to stop fuel from hugging the intake ports and pooling up. No to mention other benefits.. So trust me son. I had access to a flow bench on engines making 700+ HP.. You can see the difference is huge! Good Luck
It’s logical that if you decrease the port size you reduce cylinder filling at full throttle hence losing power, like you say it’s not rocket science but I guess some people believe anything they read
I don't understand how people come to dumb conclusions that make no sense. Matt saving the world one video at a time. From an engineers aspect, I enjoy your content.
The beauty of the present times is anyone can make a video and tell whatever they want. I advise not to waste your time watching this.
Quick comment regarding your short side example of filling it in. You can fill that in to let the air straighten itself out before hitting the throat/seat. The part you may be leaving out (or not) is that you should also widen that part of the port to keep the area the same. I agree with you that restricting the flow is bollix. Raise the short side but widen it at the same time. 2 cents from an old geezer. The "restriction" should be the valve throat. That's where you want to speed up the air (in the throat). The throat should be the smallest part of the entire port.
Cheers.
-Matt
This is what David Vizard recommends.
I watched the entire video with a open mind. This is pure bench racing. He has a lot to learn. A for effort...
Go on then, lets hear it?
The proof is in testing and experimentation. He needs to prove his theory. I know from experience too large a port hurts drive-ability and too small can limit power.. it’s all about balance and where you want the torque.
Experience in what, I.e what type of engine...
Great vid man! Ive been taught that its about where in the RPM you want your power band. As in the smaller or ''restrictive'' port is good for low rpm torque but sacrifices high RPM power, due to having high velocity at lower RPM but unable to produce enough volume for the higher RPM.
It’s not about reducing the port size it’s about keeping the bend smooth. If the bend is too tight the flow will delaminates and cause turbulence, this turbulence will drastically reduce the flow rates.
Well explained! People think high velocity means more air... there is a reason why cylinder head manufacturers advertise volume and cfm... on a fire truck the pumps are rated at 150 psi for max volume and when you go up to 200 and 250 psi the volume of water goes down... if you want more power you need to remove the restrictions
I been porting 25 years and your right on it ..it's all about shapes Port design heights what to remove so much more I really like porting 2 stroke banshees
Goodfellas Inc.
I’ve got a kdx220 can you give me some advice on porting pls 👍🏼
When the words Laminar, Turbulent, and Recirculation are not not found in the discussion...
...or flow separation, or pressure drop, or Bernoulli, or energy loss. He's got an awful lot of confidence, which would be great if he were correct.
@@brianhaygood183 we forgot Reynold's Number (!) LOL (Actually just a few weeks ago when thinking about a flow problem, it struck me that at lower speeds, viscosity dominated while at higher speeds, inertia. And then I reread the definition of RN and guess what? RN is used to determine what regime the flow is in! My fluid dynamics professor could have made that point crystal, especially since it is a monumental and very intuitive metric. But Noooooooo....
At the end of the day it all depends on valve size and port shape and port size, smaller ports will make more power AT a lower rpm but you will restrict power at higher rpm, I built a non cross flow, siamesed 292 Chevy 6 I did what we call a lump port which adds a chunk of aluminum right before the intake valve which was proven to gain power over a flat intake port
@@turkeyboyjh1 I have a friend that mastered carbon reading (heads off after every trip to the strip) - he became a voodoo engine builder whose engines got town down after every win and the tech guys would notice things he did and say, "if you fixed that, you'd go faster." Reading carbon is huge regarding combustion chamber. It's all about the wet flow. He never used a flow bench and saw no reason to use them. And yet he built the fastest engines. His all Chevy parts small and big blocks were amazing.
It's all a balancing act, swings and roundabouts. Air volume or can velocity ram a bit more in. Length of stack at certain RPMs. Great subject, many have spent many hours to achieve the optimum.
Velocity Porting is not to improve over all HP, it's to increase throttle response and torque DOWN LOW. Also It works the BEST mainly with FCR Style Carburetors to create more of a Vacuum on the back side of the Carburetor. Mostly used for Track Racing so you can get off the line and out of a burm faster. I actually Velocity Ported my own TRX450R head it make a Huge increase in throttle response and torque off the line as I stated just before this. I had each port job I would get a Base Line test.
1st Dyno Test (Stock Head --- 43HP at 7510 RPMS / 29FTLBS of Torque) 12:25 Air Fuel Ratio
2nd Dyno Test (Velocity Ported --- 48HP at 7238 RPMS / 38FTLBS of Torque) 12.10 Air Fuel Ratio
3rd Dyno Test (Port Opened Up --- 55HP at 8200 RPMS and 37FTLBS of Torque) 11.97 Air Fuel Ratio
I read those off my Dyno Charts exactly how they were printed. From Racers Edge Arizona.
I actually recently ported a new head that I'm going to test with +1mm Valves and the Valve Guides are sharpened and the port floor is un touched and exhaust ports polished with sharpened guides. Velocity porting does work. I was able to feel it when I would accelerate but had not very much top speed. Not for me unless I was racing on a Track. but I'm a lot more of a WOT person and to cruise on a long stretch rather then in and out of the throttle pumping it a lot.
TRX VLOGGER absolutley correct...velocity makes a big difference on a high performance street driven engine as well...throttle response--which you get from good velocity--- is fun...soggy response due to high flow and low velocity not so much fun...it's like a car with turbo lag but no turbo...thanks for posting....
i see a lot of torque gain with velocity, but 3rd dyno test is with velocity and the port opened up too? thats change the curve of the intake
how does those torgue curve is acting, when you acclereate you will need wide torgue
Down low torque is no good if you're on a race track... a proper race track not one of those straight line things...
Hi there. When you suggest putting the carb butterfly (6m 20s) at the same position as the epoxy filler you are over looking the fact that the flowing air would be trapped underneath the butterfly and cause massive turbulence and energy loss. However, the smoothed shape of the epoxy in the same position , if shaped correctly, will guide and funnel the moving air column into a faster moving one with little turbulence. Energy isn't really lost, it just gets converted into a faster moving slug of air which now has the ability with its extra inertia to supercharge the cylinder by drawing in extra air behind it, assuming the valve timing has a long enough port timing to allow it to do so and then closing at the right time to trap it.(By the way some engines do feel more powerful with a slightly closed throttle but this is simply because the main jet (fueling) is set too lean and the mixture at full bore is now too weak. This can easily be rectified)
The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat. By making better use of the entire circumference of the valve seat the flow rate is improved as the valve can pass more air in any given time.
Finally, another bonus is the higher velocity charge of the new port shape will swirl better as it emerges into the cylinder. Higher swirl speeds allows faster and more thorough combustion and less chance of detonation.
"When you suggest putting the carb butterfly"
- just a butterfly - nothing to do with carbs.
"Energy isn't really lost"
What energy? What is this energy and where does it come from?
"with its extra inertia to supercharge the cylinder by drawing in extra air behind it,"
- Dude, I'm sorry but you don't understand how air works or what inertia is.
"The new shape also guides the slug of air to hit the back of the open valve more evenly rather than have the air flow mostly hit the far side of the valve seat."
- This is something you have just made up...
"Higher swirl speeds allows faster and more thorough combustion and less chance of detonation."
- and now you've made it clear you don't know what detonation is.
Modern bike ports are very, very good. There isn't much you can do to improve them. Use an OS intake valve and bore the seats to .9 of the OS valve OD. That will get volume up.
On the other hand I have ported CB750 and GS 1100/1150 heads and used epoxy on the floor. They flow very well with very good velocity and have made great power through the RPM range. I use a Superflow 260 with a FlowCom and pull @ 10". The FlowCom is nice as it monitors velocity.
Yes, a good explanation of why putting a restriction in the port like that is a really badidea. Now, IF the entire port was simply straighter, (like pro stock drag racing ports are)then the port can and should be smaller... but for most engines that have to have a kinkin the port, it is much better to have the port larger to compensate for the turn, even ifit costs some speed. A lazy port can always be taken care of with better cam, but a too fast, plugged up port with too much turn causes the fuel to not follow the port shape verywell as it is much heavier than the air, leading to fuel separation and bad mixing withinthe cylinder, leading to power losses.
There is tune head porting. Depends on the application you are porting for, because if your goal is low end torque you dont need huge ports for large volumes of air/fuel mixture to enter the cylinder. You need smaller ports for more velocity to keep the air/fuel mixture in suspension to reach the combustion chamber at low speeds. Where at higher speeds you just need to get the air/fuel mixture in the combustion chamber as soon as possible, this where having larger ports within reason makes sense. Filling the combustion chamber with as much fuel/air mixture as possible is called volumetric efficiency. the goal depending on the application is to improve the volumetric efficiency at your applications engine RPM. To get the best volumetric efficiency at all rpm ranges, is to use two intake runners per a cylinder on the intake manifold, that has one larger shorter port, and one smaller but longer port. There is a valve that controls the flow through these ports for different engine requirements. Then on the cylinder head port is large for both low and high engine RPM needs.
it's all about Balance, too big a port makes for a lazy port and terrible acceleration. the goal would be to have as small a port as you can while maintaining flow #'s. In Motorsports Flow is great but Velocity is king! Port shape can also have a huge effect on flow. You make fun of the use of epoxy's well let me tell you, I have been building performance and racing engines for over 20 years I have used Epoxies(not JB Weld) in Intake ports many times and have never had it come loose. When using the proper epoxy and applied properly you would almost have to chisel it out of the port. I currently race a 10,000 RPM 4 cylinder, with ports that flow over 400cfm with Epoxy in the port, Don't Knock it until you've tried it.
"In Motorsports Flow is great but Velocity is king!"
@ one set rpm. Flow is volume over time which means that velocity plays a big part in this.
If you can maintain flow #'s and increase velocity you will fill the cylinder better. which is essentially what it's all about. More air more fuel bigger Boom More Power.
jb weld in racing engines?? haha okay that is the least professional thing ive ever heard
@@davidrose5613 That's because you can't read.
Raise the roof and the floor for more power. Cast a new intake or add good epoxy. Which would you choose?
The issues that you face with a too larger Port is loss of air velocity which equals a loss fuel atomisation which will cause loss in power so if you don’t atomise the fuel properly then you don’t get correct combustion of the fuel in the combustion chamber which equals a loss of power even if you have good injectors it still doesn’t atomise the fuel as efficiently as air velocity will so there’s a fine balance between having your ports to Big and having them too small
Wouldn't the fix be to send more air/exhaust through the port, to gain velocity?
lol. So true.. I remember my old man who's built race cars forever though explained an example of this where velocity over volume worked with ford 351c V8's with 2v and 4v heads whereby the restriction was in the exhaust ports of the greater flowing 4v heads and you would make more power utilising smaller 2v heads with 4v exhaust valves and porting as the problem wasn't getting gases in but getting it out. This was for an improved production series but was the same for a tough street engine.
If I see "does it work", I'm not looking to watch a theoretical discussion...do it, dyno it and prove his method to be invalid if you're that strong on it. Talk is cheap, and that headline is "expensive."
AHAHAHA! Some chart grabbed from the internet with NO context or validation.. and... the HP doesn't even cross torque at 5250. HMMM. If hp = torque x RPM / 5250... then... every chart in the world must cross at exactly that point and no other. FAKE dyno sheet.
@@dirtygarageguy Ouch.
People need to stop arguing on the internet and destroy some heads and post a video. PSST Engine masters has does this test and getting as much air in as possible with the least struggle is the best because the moving parts aren't trying to pull things in.
@@@aaronchadwick2682 … you mean because the moving parts ARE trying to pull things in; things in this case being air and fuel. If the pistons didn't create a vacuum how do you suppose those things would get in there?
@@chestrockwell8328 I mean't struggling to pull air and fuel in. r/corrections Good lord if you have a brain about engines you shouldn't need to use technical terms. If there a vacuum is present then don't create areas for there to be friction (velocity idiots) which causes loss of power
@J well golly gee... I wonder how it is possible to achieve 120+% volumetric efficiency in a normally aspirated engine ? I"m going to give you a hint: it has something to do with charge velocity and that old saying "an object in motion tends to stay in motion."
Wow, some interesting comments. I wont try and tell people how to port. I have my own ideas and have a home made flow bench. Im no expert. What i will do is mention all the things that need to be considered. Port size (volume), port floor shape (radius into the bowl), port roof, guide boss restriction and flow and turbulence. Area in the port at the guide boss. Area at the turn. Area in the ‘bowl’, shape of bowl to the valve seat, shrouding, shape of back of valve. Surface finish, blending in valve seats. People talk ‘velocity’, well yeah you need this for torque but what about velocity if the charge needs to turn a corner? Can you corner at an intersection at the same speed as you do in a straight line? The charge has to turn at the valve also. Simetrical ports or biased? The bigger the valve guide boss the more turbulence behind it? What is more important in a turn, the floor or roof? Do you know why? Knife edges (which i hate).
Thanks for taking the time to make this video to try to teach people what you know to be true.
I see that this is an older video and has over 600 comments. I don't have time to read them all to see if you have answered my question, which is:
Have you tried the "High Velocity Port" in practice and it didn't work or are you going strictly off your principles without hands-on experimentation?
I met who turned out to be "Motoman" once. He passedme on one of his bikes while checking high-speed tunning. His bike went from WOT to nothing at 140+mph and he pulled over to an on ramp shoulder. I could hear him approaching me for quite a distance and sounded unlike any bike I have ever heard before. It was the most efficient air pump that I had ever heard. When he passed the noise changed... there was a distinct difference between the intake and exhaust notes. So when I saw him pull over I figured he either broke something or was one of the few people that I have seen checking a plug for WOT the right way and wanted to know what he had done to the bike.
He was indeed checking his tune. We talked for a while and told me about his high velocity ports and we talked about racing, building engines and people who are so confident in their mainstream understanding and common practices that they will never step outside of the box ideas. We chuckled reminiscing about some of our experiences with people who got so defensive and obnoxious when confronted with an out-of-the-box idea. It's just hilarious to watch people spend so much time and energy to call your idea stupid and prove you wrong when they have never tried it.
My father built competitive engines all my life. He taught me that building a competitive engine is about understanding the purpose of the engine, compromise, proper experimentation, and doing it better than everyone else. He was always learning. He would allow himself to think outside of the box because that's where progress is made. He had ties to a few of the best engineers and engine builders in the world. You would be surprised to know just how far outside the box those guys get. Volocity has always been more important than CFM. Big CFM doesn't count until you get at the top 25-30 percent of your rpm range. If you can keep the proper velocity up in the intake and exhaust and tune them with proper design, you have enough CFM flow at WOT and hit that sweet spot of compromise then you will ALWAYS be faster than the guy going for biggest CFM. The compromise is that if you give up some CFM you get more back with atomization, better scavenged cylinders for more fresh A/F mixture, cooler temps, much wider powerband, etc. I just don't understand why people get so upset about ideas to improve velocity to a greater degree than the standard accepted norm. Especially in 4 valve heads! I can understand more why in 2 valve heads.
I'm not saying your wrong, I'm just asking if you have put your ego aside enough to actually try it? Just grab an old head you have laying around, do the math, do it right without sabotage, re-tune properly and make a video of how wrong he is with actual evidence. That's the video I was hoping to see.
"When he passed the noise changed... there was a distinct difference between the intake and exhaust notes."
- That is called doppler shift, and nothing to do with intake or exhaust....
"I'm not saying your wrong, I'm just asking if you have put your ego aside enough to actually try it?"
- Yes, and in the next 6 months I'll be proving it out. Also it's physics, not an opinion. Nothing to do with ego or anything related. There's something alreadyin your engine that does the same thing, it's called a throttle.... 3/4 throttle doesn't produce more power than WOT.
"Volocity has always been more important than CFM."
- 1) I'm sure you meant velocity 2) The speed of a flow isn't more important than CFM. That is crazy. Fuel volume per unit time is directly proportional to fuel and fuel per olume is directly related to power.
"Big CFM doesn't count until you get at the top 25-30 percent of your rpm range."
- That is utter bollocks.
Thank you for your reply and I look forward to you doing actual tests, comparisons and showing track numbers for evidence.
"That is called doppler shift, and nothing to do with intake or exhaust...."
-Anyone who drives on the highway much has has dozens and dozens of bikes wiz by and knows what doppler effect sounds like. Normally you don't even hear the bike until it passes you. His bike had a distinct intake noise to it. I had never heard a bike sound like that until that point.
"Yes, and in the next 6 months I'll be proving it out. Also it's
physics, not an opinion. Nothing to do with ego or anything related.
There's something alreadyin your engine that does the same thing, it's
called a throttle.... 3/4 throttle doesn't produce more power than WOT."
-Great! I look forward to seeing the results! Yes, physics. The funny thing about physics is that there are so many theories and not many laws. Plus there is a huge difference in theoretical physics and actual physics. And if you really expect anyone with any knowledge of physics to buy that a butterfly valve is anything like the shape of the intake runner then you need to talk to a physicist to tell you just how wrong your thinking is. Again, I'm not saying that your wrong that high velocity porting in the way Motoman shows is not conducive to making more power, I'm just saying that if your holding a butterfly throttle up in comparison to any kind of intake runner alteration then it just shows me that your lack of understanding is far worse than I originally thought.
-"1) I'm sure you meant velocity
-Yes. I meant "vElocity". Like I correcly spelled before and after that. It's called a typo. You see, when you are typing on a small touch screen device sometimes another finger will tap the screen and cause a letter to be typed that you didn't mean to type. But thank you for taking the time to point that out. Your so smart.
"2) The speed of a flow isn't more
important than CFM. That is crazy. Fuel volume per unit time is directly
proportional to fuel and fuel per olume is directly related to power."
I agree and disagree. If you have a port that can provide 300cfm just do to the total area it doesn't mean that it is effective enough to fill a combustion chamber efficiently. In addition to that the fuel is much more likely to fall out of suspension creating poor atomization. Maybe saying proper velocity is more critical to an efficient engine than most CFM you can flow. If you still disagree then we will just agree to disagree.
"Big CFM doesn't count until you get at the top 25-30 percent of your rpm range."
- That is utter bollocks."
-In the vast majority of engine build WITH ACTUAL PROOF AND DATA, if you take a well designed and efficient engine and bore the intake out to flow the biggest numbers it shows both in practical on track racing and on the dyno that you loose torque and horsepower in the low to mid range and only start to be more efficient in the upper 30% of the rpm range. If you are building an engine that produces peak efficiency at only the top of the rpm range then the compromise of sacrificing velocity for biggest CFM will be of benefit in some cases. However, keeping velocity is still important. So I stand by my statement.
Don't think you can hide... pressure is N/mm^2 or Pascals if you wanna be posh. So we know what mm^2 is, that's an area, so what is the N? What two properties define N?
how2powah
1) get sheitloads of air
2) get arseton of fuel
3) make the perfect mixture
4) dump into de engine
5) kaboom
6) profit
AGREE, put ALL the air and fuel that you can even if you have to pushhh it inside!!! then make the mixture the most perfect possible and HELLO 200% POWAAAAH
how2powah. turbo.
Will this fit in my Honda?
(anyone who gets the reference, I'm proud!)
It’s not the same for every single engine, for example, the ports on a 351 Cleveland V8 are too big in standard form but work well with a more aggressive cam. The 351 Windsor has smaller ports which are suitable to the stock cam, not as beneficial with a more aggressive cam. Velocity and flow are as important as each other, it’s not a one size fits all, it’s the complete combination from compression ratio, port design, cam profile, valve sizes etc. Bigger is not always better
way I see it, I trust manufacturers to calc out this shit to perfection. that said, if I'm working on my own machine, I'll polish out all the casting shizz for a clean port. not because it does any good- but because I fucking like it that way.
geogineer Thats what a old engine tuner told me. Get the inlet and outlet ports as smooth as possible. From the factory they ate a bit rough to say the least.
They don't... Perhaps in F1, they put som effort to it, and look at those ports... their smallest cross section is actually quite small compared to valve size vs. a normal production engine, and the venturi-style port has a good diffuser section before the valve and seat insert area. As there is none to little pressure recovery to be had in the very flat combustion chamber... Typically the port mCSA of a F1 engine is roughly 75% of actual usable valve curtain area. Your typical OEM car cylinder head often has it the other way round... Port mCSA is often larger ( often 125%) of valve curtain area... Production engines (other than bikes) as a whole seldom moves above 100hp/liter without the aid of forced induction... their ports flow just "good enough" to get the job done and is mostly configured towards meeting emmisions, and quick/easy casting and manufacturing. And with regards to "polishing" a intake port... if your engine got anything else than direct injection you loose power with "shiny" ports... If you want a port injected engine that has poor start and idle, and low to mid-range power, whithout having any added benefit at high rpm WOT, In addition to be more prown to end-gas detonation... by all means... go ahead and polish the living shit out of it... It's not my loss :)
Slick ports don't allow for efficient fuel vaporization. Better to have roughness and small surface turbulence.
WELL PUT!
Njål Nilssen you are completely right: the port in production engines is bigger then what the curtain area flows. In doing this the valve seat controls the amount of air entering the cylinder. Not the incosistent cast port. Therefore a smaller port works !!!!!!!!
ok , i haven't got a clew on how did the epoxy port filling come up or the arguments that were being used, but after a while it´s just too much, so let´s get some things clear:
1-the biggest port possible" open head bla bla" IT´S NOT THE BEST OPTION, with such port you would only be able to achive a maximum 100% VE (cylinder volume at atmosferic pressure), a well designed head can actually achieve well over 100%, get the f20c for example it gets 110% VE from 6500-7500 rpm.
2-a well designed port will create an "air ram" due to the air mass momentum when the piston is at bdc and the intake valve is still open, explaining point 1.
3-epoxy , or any other type of filling, can be beneficial if for example you want to straighten a port and have to remove alot of material but still want a reduced port volume so point 2 can be achieved!
4-when you close the throttle you only increase air speed near the butterfly valve and not the entire port like you need for it to work!
5-if you have an engine that isn´t direct injection the fuel atomization will be better with a faster moving air charge.
greetings, hope you give it a thought
They main issue is mistuned camshaft timing - intake manifold length, exhaust etc. pp. -> less pressure drop is always a good thing - but you need to get you intake/exhaust timings tuned to this. At carb engines a massive reduced pressure drop is an issue like on old V8 engines, the vacuum is too low to keep the carbs proper working. So you run into different issues (slider doesn't open maximum for example or slider spring is too weak and bouncy), you have to understand the impacts. And yes big does not mean ideal .
The way how this is explained is exactly how my fluid mechanics lecturer explained the rate of flow through a tube. You want more flow through a tube, get a bigger tube. Adding shapes to an otherwise cylindrical tube will create localised areas of turbulent air flow and hence reduce the overall Reynolds number ie the velocity of air flow. This video is the best explanation I have seen explaining fluid motion in very simple terms. Well done.
I do love the moto man rants lol keep them coming mate they always make me smile lol
I guess the point they got wrong was mistaking lateral velocity of the air for Volume stream i. e. Flow.
Pressure, Flow and resistance are interlocked: Pressure is equal to Flow times Resistance. But it is important to note where these Values are measured.
The Pressure in this formula is the Pressure needed to create that flow through the restriction.
It is not the Pressure of the fluid after passing the restriction.
If you keep the flow constant and add a restriction, then the Velocity of the air DURING THAT RESTRICTION will increase, as well as the Pressure in front of the restriction needed to keep the flow constant.
This will not give you more Horsepower though, because the limiting factor for HP is how much volume of air you can squeeze into the Cylinder to burn more fuel to get more power.
So, you want to maximise Flow.
And to do that you can either increase Pressure (crank up your boost or reduce the volume of the intake by making it SHORTER, not NARROWER because that would increase restriction) or decrease Restriction.
These rules are true, but keep in mind that they are for static pressure and constant flow, which is not the case during the full engine cycle, only holding true for the explicit intake/exhaust stroke.
But the effects of the pulsating pressures and flows in the intake runner do not completely invert the rules stated above.
My guess is, that someone really mistook flow for velocity and tried to maximise that, which would make narrowing down the intake make sense.
Unfortunately that is not true.
The only point where i think narrower channels would be viable is, when the intake volume is so big, that the Turbo/Supercharger/ambient pressure cannot replenish air and Pressure in the manifold fast enough
(analouge to a too big voluminous intercooler increasing turbo lag).
The guy who said that restricting the port size to increase flow is off his nut. Ports are by their very nature funnels. The limiting diameter is the size of the opening that the valve covers when closed. The shortest distance between two points is a straight line except in the case of guns. They have spiralled tubes and that spiral gives the bullet rotational momentum to stabilize the bullet after discharging from the barrel. The length of the barrel and the pitch of the rifle spiral determines the final velocity along with the powder charge and make-up of the projectile etcetera. In short, the longer the barrel the faster the terminal speed of the projectile exiting that gun barrel. Enlarging ports is only a part of cramming more air into a combustion chamber. The main goal is to straighten out that port and runner to allow the air to enter/exit as quickly and smoothly as possible. Spiralling that runner could potentially allow a larger volume of air into that port because of centrifugal force acting on that column of air somewhat similar to a bullet. Dimpling the runner, similar to golfball dimples, could also be another way of stabilizing that column of air. Reducing the vortices that would build up as air flows through a funnel tube is the other consideration. Diffusing striations, similar to the rear undercarriage of racecars, would also reduce vortices in the runner. The fewer the vortices the straighter the path of air. Slightly dished in valve faces could be employed to give a negative vortex in the combustion chamber sucking in more than otherwise would be possible. Using exhaust scavenging is another way to suck in more air. The mere fact that the size of the valve restricts the flow is the ultimate determiner of air velocity. Squeezing a large volume into a much smaller volume speeds up that air mass. That was quantified by Mr. Bernouli and Mr. Venturi. I hope that I haven't made an asshat out of myself. I haven't studied physics for many years and I haven't worked on large shipborne diesel engines for about as long. Thanks for the segment.
This was well done for a subject that people act as if its black magic, well explained with simple and understandable analogies, good stuff. A great sequel to this would be intake plenum size!
Well explained again Matt. Doesn't matter. Some people will never understand. Same kind of people that think they can use their car's engine driven alternator to crack water into Hydrogen and Oxygen and get better fuel mileage. Or they think because they saw a guy with an electric supercharger making boost on youtube then electric superchargers must be a thing.
The only time velocity matters is at the venturi of a carburetor. No one racing bikes, or even cars for that matter, is going to be using a carburetor unless it's a class rule. Even then, they are not at idle/part throttle most of the time. So it still doesn't matter. Mass flow makes power. Small ports ruin flow. Thus they ruin power. You can white board all the diagrams in the world and motodouche is never going to change his mind.
"Well explained again Matt. Doesn't matter. Some people will never understand."
- aw well, if I can deter 1 young lad then its worth it lol
I never heard of this silly shit before.sounds like a good way to destroy your engine when you run a big chunk of J.B. weld through it.
Always great when your piston plays 'smash the expoxy' game lol
The Workshop you make great videos :). thanks a lot man....
could you pleace make a video where you explain how the 2 stroke direktinjektion engine like brp gets a ignitable mixture during the upstroke? i mean it works, but how it works in this short amount of time and the shit air flow of a 2 stroke.
please keep up your good work. best regards from germany ^^
Already done the video, just need to edit it and post - matt
We owe it to gas gas for dirt bike injection. anyone who says ktm did efi on 2 strokes is full of shit. Gas Gas brought efi to the 4 stroke dirt bike world, and then, they brought it to the 2 stroke world. some of their current 2 stroke trials bikes have efi
Closing off the port in my rocket engine works great. It was once the same size all the way and just blew up. So the restriction did help. LOL
There are some odd conclusions made here. You have several logical fallacies in your argument against a "high velocity" port.
Perhaps we need to be talking about Volumetric Efficiency. Yes, you can achieve better volumetric efficiency with a PROPERLY DESIGNED port that might be smaller in size and volume than the original stock port. By adding material to a port we are not trying to create a restriction, we are attempting to remove a dead air zone where little air flow is happening. This is port design 101. By your logic "bigger is better" and we know that simply is not true. Porting is a science and a huge industry. The porting industry exists because ports are not perfect.
The best ports are not the biggest. The best ports don't just flow the most CFM. They need to be able to flow is at as high a velocity as possible to raise the VE beyond 100%. Sometimes we need to remove material from an area of the port, sometimes we need to smooth areas, sometimes we need to add material. Usually all three if the OEM port was not well designed.
A case in point is a motorcyle port I changed to be smaller and better designed than the OEM port. The new port was MUCH smaller but we picked up substantial flow. On the dyno we increased a 1000cc motorcycle's power by 15HP. This is with no compression or cam changes.
"raise the VE beyond 100%" Heh funny guy
@@robingrantgast2065 It's known as "inertial supercharging", see here:
en.wikipedia.org/wiki/Volumetric_efficiency
en.wikipedia.org/wiki/Inertial_supercharging_effect
@@robingrantgast2065 I found one more for you:
www.autospeed.com/cms/article.html?&A=1127
@@robingrantgast2065 top race engines achieve 120% volumetric efficiency (a better term is Delivery Ratio).
@J You need to review the basics if that's what they are telling you. Please educate yourself and stop relying on whatever you are calling common sense. If you are interested i'd recommend books Harold Bettes , David Vizard and John Baechtel. You are full of crap and this is coming from a person who actually owns a flowbench and does dyno testing every tuesday (engine) and wednesday (chassis)
Great video! 9 out of 10 for science content. The pressure doesn't drop when you restrict but let's let that slide. What I think these guys are really doing is just smoothing out the casting of the runner on the cheap. But believe it or not first time I have heard of this. We always ported heads by removing material and smoothing. You do lose some low-end torque but gain HP.
Also great work on fluid momentum. It plays a lot bigger role than most understand. An engine running at 6000 RPM is moving air around 270MPH in the runners.
There are many points in this video I disagree with, but literally that's a very basic law of physics. As speed of a fluid increases, it's pressure decreases. It's how venturies, chimneys, and aircraft wings work. Coming from an aircraft mechanic specializing in environmental systems, but really this is high school science 101.
@@dsan94 You may be confused as to the which side of the restriction you are thinking of. Post restriction the pressure will be lower. In front of the restriction the pressure will rise (or in the case of vacuum decrease).
The way I see it, you have atmospheric pressure outside the throttle body and dropping pressure in the cylinder (as the piston falls). The tendency of atmosphere to equalize itself is where the molecule movement moves the outside air down the port toward the lower pressure in the cylinder. The absolute BEST that could happen outside of forced induction is a 100% equalization of cylinder pressure to atmospheric pressure. We know that's not possible.
Air has mass, and mass in motion will have momentum.
Engine builders who want to tune a given engine to have greater lower end torque typically employ several things to achieve that. One of which is smaller port sizes per a given cylinder displacement. That achieves higher flow velocity through the port at lower engine RPM. Among other things, this creates faster cylinder filling, greater air mass momentum, at lower RPM and increases torque at lower RPM. Of course these types of setups result in limited upper RPM power due to less efficient flow at high RPM.
The perfect theoretical engine would be one that has infinitely variable port size, infinitely variable intake runner length, infinitely variable valve timing, infinitely variable valve lift, infinitely variable compression ratio, and infinitely variable exhaust runner diameter. Wouldn't that be some engine!
A NASCAR Combustion engineer once told me:
"The best port would be a straight port from the beginning to the end of the port. If you can see the exit of the port from the entrance, you're doing better than if you can't."
Also, there are studies about "optimum" intake velocities of air, but these "optimum" velocities are only applicable for certain ranges of rpm. It's all about what band of RPM you're designing a head for.
This is a super interesting subject! I’ve heard really well known high performance engine builders talk about how equations and modeling only get you so far (roughly in the ballpark) when trying to increase performance and it takes lots of experimenting and dyno testing to truly arrive at a winning design due to the many interrelated variables that effect engine performance. (It’d be cool though if people could talk about their ideas without talking down to people with different ideas or understandings.) When it comes to intake paths not all restrictions are the same. Your analogy of pushing people through double doors isn’t completely comparable due to the Bernoulli principle, which is roughly the idea that as a fluid moves through a pipe past a restricted area (think of the restriction being a curved surface like an airplane wing and not like a flat butterfly valve) that fluid speeds up around the restriction which also causes the pressure of the fluid to drop at the restriction. People being pushed through double doors wouldn’t be subject to the effects of the Bernoulli principal like a fluid would. So I could see how someone could think that using the effects of the Bernoulli principle by slightly decreasing the diameter of the intake through the use of a curved restriction would increase the velocity of the air thereby increasing the amount of air getting into the combustion chamber as it rushes past a given size opening/intake valve, however from a physics standpoint, you can only get as much air into the combustion chamber as you get into the intake first which agrees with what you were saying in the video to a point. Although, increasing the speed of the air entering the combustion chamber may cause the fuel and air charge to be more thoroughly mixed which would allow for a more complete combustion of the fuel air mixture which would increase hp. In addition to the complexities of intake geometry, I know acoustics/harmonics have an impact on how the air/fuel moves into and out of the combustion chamber which is another whole level of complexity. Also it’s has been proven that texture is also important to a degree and having a slightly rough texture on the intake surfaces does allow for better performance as opposed to having a mirrored finish do to creating a smaller boundary layer of air close to the surface of the intake thereby creating less overall drag. Anyway, I think it’s badass subject and I’m sure no engine builder is ever done learning. ✊🤙
Excellent analogy with the butterfly valve, poor old Motoman, stitched up again. lol
Just found you, watched 3 videos, and I love the way you tell verything! I gave u my Sub! keep them up man! love for 2 stroke.
Fact is that the smaller port WILL have small gains ONLY IN LOW RPM. But without the large ports, the engine will suffer the mid and high range.
Motoman was talking about peak HP and torque
The old adage, you don't get something for nothing, is very true.
In all actuality yes "high velocity" porting can cause resonance to occur and create more power, but I think motodouche doesn't understand the actual science once again. The power gains will be miniscule and at such a tiny rpm window that its not even valid! Plus as matt explained rather humorously, it will decrease overall topend power and power under the curve. People who poorly understand something, take 2% of the facts and draw a incorrect conclusion are the bloody worst, sod off motodouche lol
This video is all opinion and no science.
You have an anime profile picture
I don't know who this motorman you are talking about is... But I think he has missunderstood the consept if he does it the way like you draw it here..., it's too close to the valve, the port should have been straighten out, the bowl filled slightly in the roof after the valve stem and It has nothing to do with resonance, but more so about increasing velocity WITHOUT restricting flow. Closing a throttle a little is a pure restriction, because it has a very poor pressure recovery behind it, so all it does is creat a restriction as there is no working diffusor behind it to convert velocity back to pressure. Most of the instances where "velocity-porting" (stupid name really) works are on engines with combustion chambers that give a poor pressure recovery AFTER the valve. like most 4 valve head and especially on high compression MC-style heads with a very flat pentroof. Usually the valve window it self is the main restriction, thus shrinking the port in the correct manner (as it's usually overkill compared to the actual flow of the valves) you gain both higher velocity and flow due to better pressure recovery due to the formation of a proper diffuser (aka the means of converting velocity to pressure) the higher velocity you achive without restricting anything gives you a better "ram" effect due to higher inertial forces, and 120+ % trapped VE is common on NA engines. And believe me... not all OEM engineers has got the ports right in a long shot... sometimes perhaps with regards to emissions, and emissions only, but what performance goes, not by far...
I work with hydraulics on automotive and yes motorcycle lifts. The orifice restricts the volume and increases pressure. In this case, the pressure increase will be lost filling the volume on the other side of the orifice. The old trick of trying blow a ball of tissue into a soda bottle will also be a factor as well.
Good point on vvt & similar. Timing of the valves & size. When port shrinking works it's apparently a quick fix for excessive duration. Or just bad timing.
I just acquired a 02 Buell Blast. An improved roller cam in couple years might be sweet.
@theworkshop Do you think you would see better vol. Efficiency at lower RPM range with this nozzle idea? I agree at high RPM you want that baby wide open. The reason I bring this up is I was running some engine simulations with 2 valve vs 4 valve and the 2 valve had better vol. Efficiency at lower RPM. That was a head scratcher for me but concluded that it was because of higher velocities...
Hi Matt, your going to have to do another video on direct injection porting. This is totally different, we use diverter vanes & other ways to not blow the fuel into the cylinder wall. Things changed in a big way when we got to direct injection. The old ways just don't work. Keep up the good work..
There are those that never will understand an engine. And there are those that will understand them.
Most likely the latter is the majority unfortunately...
or if you want to turn around the other way you could use a Shop-Vac as an example take your normal to inch hose and modify it to a 1 foot opening completely sealed no leaks will probably not even be able to suck up a leaf or a piece of grass now when you reduce it back to the original 2 in diameter size hose it has plenty of suction for that size displacement pump whatever you would like to call it ... there is always a certain size for the correct flow volume velocity pressure however you like to put it for different applications bigger is not always better
When you get to the limit of the flow of the valve slow moving air will not help you, high speed air will however as well higher pressure. The valve is only fully open for a very small time but its opening and closing time is a lot longer. This is why we want fast moving air to actually hold some pressure behind the valve waiting for it to open. Air is quite heavy and getting it up to speed takes a while and so we want to keep it moving and not to lose momentum
What? Do you know what this is? PV = nrT
@@dirtygarageguy I know putting up the ideal gas law makes you seem smart, you have however missed the point.
Ford solved this in the 1990's by adding intake manifold runner controls (IMRC) that block the 2nd intake port in their 4V "b" heads (most commonly associated with the Mustang Cobra), opening the 2nd port after 3250rpm. They just weren't getting enough torque at low RPMs without this and emissions were simultaneously below requirements. The down side (beside the extra mechanical parts) was that the secondary valves stems built up with carbon to the point the valve stem was easily double the diameter as it passes through the port due to lack of fuel to keep them clean in daily driving. I know because I am rebuilding one.
A few people on here would do well to read the works of David Vizard, a man who spent his whole life on a flowbench and dynomometer. What he doesn't know about porting etc..
(That's a serious one for a change!)
69waveydavey or Graham Bell. his 4 stroke tuning book and his 2 stroke tuning books are updated as new vehicles and theories happen along.
My ports are too big. They're restricting my free flow exhaust!
Mate you have no idea... if you close off the port at the throttle body you are restricting the air flow. if the port gets smaller as it gets closer to the valve the airflow will speed up.
You are forgetting mass flow rates, the speed of sound and pressure differentials
I don't pretend to know all that stuff... you should learn the basics before loosing yourself in all the other stuff that way you would get less negative comments.Learn to take your mistakes on the chin or understand the stuff you are talking about first.
@@dougharvey9766 actually he's pretty much spot on... it's something motorcycle race engine builders focus on... a restrictor plate on the intake is used to keep HP figures down... same with race car engines if the car goes above HP limits they install a restrictor plate to reduce the amount of air getting into the engine... all this does is amplifies this practice... if you blank off 10% of each port on a 4 cylinder engine you are losing 40% of usable airflow... however, if you look at the ports on a factory turbo application they are shaped in such a way because the air has no way of returning back to the intake because it is being "forced" into the cylinder...
The only way to add pressure to any engine is to force the air into the cylinder while defeating the atmospheric pressure. Please check your local elevation for that info. One thing to mention when it comes to air, when restricted under pressure it will expand on the other side of the orifice: causing it to become colder allowing the air to be dense. That will make power.
I agree with you that this idea doesn't work, except possibly over a very narrow rev range.
I will add, however that if an engine at full throttle seems to go a little faster with the throttle slightly closed, it needs the main jet to be replaced by one which is slightly larger, as the aforementioned condition indicates a weak mixture at wide open throttle (or WOT).
I think what Motoman was trying to do is improve the short turn of the port, I think it's along the lines of applying Bernoulli's principle, the same way flow is improved at the valve seats at low lift through various seat angles
Want more air go turbo lol
Love the butterfly valve analogy sir.
When you have a chance, search "Toyota dynamic force engine". If their comparison images are in any way accurate, they pretty much block half of the valve face with a "ramp" in the port and concentrate the flow on the upper half.
Yes for low speed - to increase the port velocity at low flow rates - this increases low end torque - but it increases in port cross-section when the revs increase. On motorcycles who wants to sit at low revs? Just drop to a lower gear.
@@dirtygarageguy A port being larger does not automatically mean it's efficient. Often a smaller, but efficiently designed port will start flowing sooner than a big one, but keep flowing where the big one finally gets going. An example: This FSAE team used a novel additive manufacturing process to produce an idealized intake manifold that allowed a CBR600RR engine to reach it's red line despite breathing through a mandated 20mm restricter. 3dprint(dot)com/201534/3d-printed-intake-manifold-carbon/
The the venturi should be set up in the area right before the valve seat so a high pressure zone is created right before the cylinder.
There is such a thing as too big a port and it comes down to the loss of fuel atomization at the low end due to lack of air/fuel charge velocity. Toyota and GM used swirl ports on some of thier engines back in the 70s and 80s to keep good atomization and emissions down.
"Toyota and GM used swirl ports on some of thier engines back in the 70s and 80s to keep good atomization and emissions down."
- because of the use of either carbs or single point injection - with multipoing injection they stopped doing this. The reason is due to flow seperation around a radius.
Maybe this point has already been mentioned in these comments..
To say that the 'biggest port' possible will flow the most, or that 'no port is too big' is not accurate.
The limitation in most cases is the valve diameter (i.e. The area around the valve seat).
Given that restriction.. the port that would flow best into that restricted area is not the largest port, but the port with the size to optimise velocity and flow.
In other words..
Choosing to place a restriction before another restriction (that you had no choice in.). can make sense.
If the restriction you placed is less restrictive than the valve seat area there should be no issue.
A port can easily be too big for the valve seat area (restriction).
I wanna here your thoughts on dimple porting and polishing
Both Yoshimura and Tom Houseworth used JB Weld on their ported heads in the air cooled GSXR's.
Definately - its easy to mod ports in hind sight.
It was common to raise the port floor on early R6 s look at tony homes and other iom sidecar engine builders .. I would give 2-3 hp on the 99 600's just saying...?
No one is talking about temp. Doesnt thermal dynamics have the biggest part of what we are discussing . You have a cool air charge trying to be forced into a hot chamber. ie higher pressure, yes the piston is in the charge stroke but the temp is fighting that action. The pistons vacuum capability decreases exponentially with rpm. so isnt speed of the charge the answer. IDK just thinking out load
Temp of what?
So going by this mortorman logic, I plug up the inlet tract completely, I get infinite power. Good to know.
That's not his logic. That's your attempt to trash him.
I love your stuff
You haven´t ported many heads haven´t you?
In short:
Motomans ideas are not wrong, just a bit or a big bit excessive.
When portiing a head you want a 'small' area(venturi) in the runner to add speed to incoming air.
This area needs to be at a certain distance from the valve, to tune it for a certain rpm range.
Your example of lifting the head and dropping a shitload of air in doesn´t increase VE above 100%(not making any big power numbers)
Racing engines got about roughly 120% VE, experimental engines have reached up against 130%.
How to do that?
Well you add speed to air to get high inertia of airflow(but you cant go over mach1).
This can load cylinder more than 100%, creating a positve pressure at the valve.
This 'venturi' needs to be carfully shaped(certain area of valvediam) and in correct place to let air after venturi diffuse and get higher pressure again before reaching the valve.
If this is succesful you can this way overfill the cylinder and get above 100% VE.
Study on..
Not even gonna start with this one. Wait for the fucking videos, like I said IN this video - jesus
*lol*
Study on little wannabe.
(but i must confess, you talked so much mumbo jumbo i got tired and didn´t watch the last minute)
well..
As i have seen a lot of your clips and many of them are some kind of just mumbo jumbo.
put on a cool shirt and draw some stuff on a whiteboard doesnt make you mr knowitall.
it might feel like it.
question though: did you ever read my first sentence in my first message?
a advice for the future: be careful what you are preaching people might belive you.
advice two: take a couple of hours study on shaping ports on speedtalk forum.
then get back to me.
study on!
it's like a bend in a river isn't it? the water on the inside of the bend slows down, and adding material will just increase the angle of the bend and slow the flow even more
You want to get the A/R of the port to be just right, so its essentially non restricting but still tight enough so that the air hits the closed valve with a velocity that causes the air mass to compress until the valve opens again. This way the head will suck in denser air and thus make more power. Its just like the way that header pipes need to have the right interior diameter otherwise it will be too restrictive or you wont get any scavenging at all.
That motoman guy is still around? I first heard about him like 10 years ago. It didn't make a lot of sense back then, either.
Saw how porting made a big difference in the 60s. If I get my new Atlas porting and polishing seems the way to pep it up without changing parts etc
Almost every engine I've seen in BSB & BSS is running high velocity ports. Mainly fillling the ceiling to alleviate sharpening the bend. I've personally gained large chunks of power and rideability filling ports on various engines, and know many other tuners who have too - In some fairly interesting fashions. Don't knock it until you try it!
No they don't. I have a friend (Andy Firth) in BSB. Stop talking shite.
My though is that this is a good idea, only if there is variances in the area of the port in different parts of the port. If the short side of the port radius is larger that the rest of the port you will loose port velocity. But it may not be necessary to fill in the entire area. The port should be flowed as you progressively fill it in.
Makes so much sense
It's like sticking your finger over the end of a hose pipe
why didn't you just use the carbarator example....you know the ventura principle. or is that too much for you...........what's the difference between you and a rotorary engine?
They've already extensively tested and proven the concept of port velocity relative to torque. Port shape directly influences velocity, which directly influences torque which directly influences your final hp numbers. As far as high rpm hp, yes you are correct, the shortest, biggest, least restricted port is better, until you become limited by piston speed. The problem is, people don't redline it everywhere they go, at all speeds. You'll need torque lower in the rpm band to move the loads. And so ports are shaped and sized according to the application. Smaller, higher velocity ports perform better down low, but they will eventually become limited by how much cfm they can flow, which will limit your hp at higher rpm. And you can't just hog em out because everything between idle and wot will be missing, as far as power is concerned, turning your money pit into a dog. Just size and shape your runners relative to your target powerband and you'll be fine. Until we get infinitely variable intake runners, that is. Or just use an electric motor.
"They've already extensively tested and proven the concept of port velocity relative to torque."
- where? A link would be awesome.
What people talking about velocity or mean port velocity is all true to a point.there are so many variables in port designs. It's a inch below and above the seat that's where 65 percent of the flow is 25 percent around short turn and vavle guide and the runner 15 percent. a well designed port should extend a inch or 2 into your intake runner .flow brench and mathematical jumbo will help in performance gains . another place not to over looked is overlap just when piston is parked a tdc its overlap that's helping incoming charge to be drawn in.but on saying that a longer stroke engine is parked at tdc longer then a short stroke engine .Cam, angles cut into seat and valves crank angle and it doesn't stop as I port heads and I'll share this variables that's what it's about
Port area is good for mass flow up to a point, but accurate carb metering needs to have a strong vacuum signal so port velocity is important too - its about getting the compromise for the intended use and rider preference.
To a degree, and the manufacture has already done this to a point. More on this, this weekend.
Matt, he has seen something that the drag race guys do use. They don't use the epoxy near the valve. They use it near the beginning of the port when using a single plane intake feeding all the ports. What they are finding is that the floor of the port is not being utilized very well. What they are doing is raising the port.
I am 100% serious. This is a wide open throttle situation where max power over the largest curve possible.
What the guy I talked to said (he built pro stock bike heads..probably 10 years ago) was, The engine can not utilize the port WOT at the RPM range we run. The air velocity is so high, the bottom of the port has a boundry layer that is influencing the flow in a negative way. They raise the port floor and it comes to life....mostly because of the valve actuation, time it takes to open, time it is open, and time it is closing.
I will send you some pictures of some V8 stuff he did and the improvements it made.
That said, this work is no where near the valve like you have drawn.
Imagine the top of the port as you have drawn it but the bottom floor is lower than where the curve down to the valve is. So, the transition to the valve opening is by far and away the restriction at WOT and with the valve at max lift. All they are doing is raising the floor to attempt to minimize the transition. That transition is key because flow at that area needs to be streamlined as much as possible because air particle momentum can influence boundry layers and further minimize flow potential.
That said, everything I have seen is on 2 valve per cylinder heads.
And this is why modern engines have straight runners - more on this in a future video
I know...starting with shit
Toyota back in the eighties had TVIS. You had monster ports, with two intake runners per port. There was a TVIS plate between the head and intake manifold which contained butterflies that blocked off one intake runner per cylinder up to (I think 2800rpm). Closing off one of the intake runners at low rpm increased port velocity and the whole arrangement also meant that air fuel atomized real well in the combustion chamber. When the engine revved beyond 2800 rpm the butterflies would open in the secondary intake runners and more air fuel could get in with an adequate port velocity.
Motorman is right that ports have gotten too big, and this is at the expense of low end power. You are right that ports need to be large to support flows for decent power, but this comes at the expense of low rpm port velocity. It depends upon a customers requirements, whether they want high rpm or low down zippiness.
We are talking motorcycles here and they have secondary throttle valves.
Secondary butterflies in a motorbike engine have fuck all to do with port flow. The secondary butterfly is ecu controlled so a hamfisted twat doesn't bog the motor when accelerating. Works in a way like cv type carbs.
As for adding epoxy to reshape the port (raise the floor) of it didn't work Hrc wouldn't have done it to their works bikes.rvf750 comes to mind.They use epoxy as the rules state they can't weld material to reshape them.
Ever heard of v&m racing they made tuned the rvf for Honda UK. And guess what they used epoxy to help reshape the ports.
One huge error in your theory is not thinking of the pressure wave of the valve closing . In a big port can slow or even stall the in coming charged air. Where as high velocity ports (epoxied) will effectivly negate this issue.
Go do some proper research into this . Ask fw developments they do it all the time .
It sounds like to me just start the air intake out as wide as possible within practicality and gradually narrow it down to the entrance of the intake manifold for the best combo of air flow and air velocity.
Independent throttle body with long strait intake it will stack the air and create a creator force against the valves. However, you need a long and as straight as possible intake pipe so positive pressure is still traveling to the heads. If it reverses direction your screwed. Look to steam injectors for the concept of velocity.
You don't undestand.
reshaping a port is not closing a throttle.
reducing a section with a good aerodynamic profile allow to increase air speed ,so ability for air to go deeper in the cylinder,pulling more air behind itself.
closing a throttle plate create a lot of turbulences behind it ,reshaping a port do not,but oinly changes air speed.
air is compressible,It's not a flow of water....
It's a basic aerodynamic concepts .
Look at Bernoulli principles, Venturi principles etc...
You have not a real idea of what you talk about by lack of knowledge.
With your idea of air flow, planes and birds couldn't fly...
Obviously never heard of a choke point and mass flow rates - shame for you that you're an idiot.
Like i said,air is elastic.
You can have more mass flow rate with a turbo while it's squizzed in the turbine...
Poor choice of words there - elastic is generally described as 1 of 2 things -
Elastic deformation when a material 'springs' back to its former shape/profile. The region before yield an plastic deformation begins.
or
Linear elasticity - based on hooks law etc. These are all solid elastic transformations.
Liquids and gases do neither, because liquids and gases do not form crystaline structures that are bound through the metallic or covelant bonding.
Yeah,
Try to explain yourself in technical french without looking at google like you did to get two definitions,and then you will can open your mouth (in french of course)
You understood me : air is a fluid,compressible, contrary to a liquid (wich is too ,but just a little)
You can push or pull a compressible fluid through a reduced section without loss of flow mass ,simply because its speed (flow on time) is good enough.
It's exactly what you do in an engine head when well designed.
Formula 1 cars did use that during the naturally aspirated era and had a huge volumetric efficiency,they were even able to have positive pressure in the intake when the valve was closing.
The fact that air speed is appropriate and compressible.
That guy IS doing it wrong for sure. He probably does have gains somewhere, probably at lower RPMs... but, unlike a system designed to keep the velocity up like a Toyota 4AGE's T-VIS, he cannot remove the restriction for higher RPMs (not counting the J.B. Weld breaking away unintentionally.) A dyno plot would probably show both the claimed gain and the loss elsewhere. The T-VIS uses a throttle like valve to close off one intake runner to each cylinder, and over 4500 rpms or so it opens them up and you feel all the fury the Japanese could put into a 1.6l 4 cyl. in the 80's. It's one reason why the NA Toyota AE86s and MR2s were great.
Even me being a numpty got that good video
Look up Dave Vizard, he knows what he is doing as well, he writes books about porting and building high hp engines.
The ONLY place that I could conceive of this having any benefit at all would be in NASCAR restrictor plate racing but even then you would not be reducing the entrance size but just matching the size of the "plate" so your flow does not bunch up along the hard edge of the restrictor plate.
love the explanation...
funny side note i tell people who ask me how to make more power
" the difference between your Hemi and Top fuel Hemi,,, more air than most jet engines suck in, Fuel that contains air because why not and spark plugs that draw more amps than your friends speakers in his trunk... why all this you might ask well,,, it's like they say there is no replacement for displacement how ever it is the air they are talking about not the engine size displacement"
that is normally when i get the what look so i dumb it up. get more air in the cylinder and follow suit with every thing else more air more fuel more spark and timing if you dare.
i have run epoxy ports in a drag bike for nearly 10 years and it is considerably faster than similar spec engines at ALL engine speeds.It was in the worlds fastest and quickest bikes right through the 90s on any serious drag strip.Each one of youre seemingly reasoned arguments had ignored the reasons that make this work,although you are right on the point that this is about volumetric efficiency and massively affected by cam timing but youre just quoting it ,3.05 proves you just dont really understand.There is so much that you have proved here that you dont know that the simpleist thing i can say is just because you ignore something wont stop it from happening.This HAS been proved at national level in races to work no matter how much it makes you swear.I dont see it working with modern down draught Ports tho and also doubt you have ever sucesfully ported many heads(ye gads please dont)or you wouldnt only understand half of the picture.You have surprised me opening u a port like you describe will KILL any decently designed head,.read what others have said here and you may lern something,youre half way there,5 out of ten
I have been searching for answers on this subject for some time. I also work in the pump and valve industry. I can't see how you think restricting the port size will not increase velocity - it does and how you think that pressure will drop - it doesen't. I work with pinch valves, in principle a rubber tube inside a casting that can be closed by compressing external pinch bars. The most common problem for high wear rates is when people try to use a control valve incorrectly selected so the valve is so tightly closed it has extreme velocity through the aperture and very high inlet pressure.
Building classic race engines as well, I would not put anything on an inlet tract that could be sucked into one of my engines. Great subject this but there so much conflicting information, my engines are high compression, twin cylinder, air cooled, four valves per cylinder, DOHC, ceramic coated pistons, competition cams, adjustable valve timing, still running on high octane petrol, not gone the race fuel route yet, I am convinced that there is more power to be had from the engine and its in the head
"I can't see how you think restricting the port size will not increase velocity - it does and how you think that pressure will drop - it doesen't. "
- Velocities do increase, but the pressure drops - therefore. What matters here is time. Valves are only open for a finite time due to valve timing. If you increase the velocity the pressure drops for the same mass-flow rate. The issue is the pressure drop vs time.
"The most common problem for high wear rates is when people try to use a control valve incorrectly selected so the valve is so tightly closed it has extreme velocity through the aperture and very high inlet pressure."
- Inlet pressure is the key here not mean pressure.
JB weld in an intake would scare the hell out of me.. That stuff dries rock hard, but I wouldn’t feel good about it.
Hey mate, dunno if it's the right question to ask on this vid, but it's in relation to tumble, if I created (in an ideal world) a flow from air filter to valve/combustion chamber, that had 10% (arbitrary number) more flow than needed, then created obstacles (Also arbitrary) to the tune of that 10% (gauged by a flow bench) to create tumble, would that be beneficial to performance if done correctly? Or is it just better to have straight flow for the amount needed.
If it helps this question is in regards to an across the rpm range tune, over a peak window of rpm tune.
Thanks in advance mate.
Great question and I think I get what you mean. So tumble is called turbulance - which ever way you wanna cut it it's like this...
Turbulance is great for fuel mixing
Turbulance is shit for mass air flow.
This is what injectors are for. The Z900 I have now has 12 pintle holes in each injector. This increases atomization, which reduces the size of fuel droplets. Why would you want that? The smaller a sphere the greater the surface area to volume ratio. In other words - the surface area increases for the same volume. Why does surface area matter? Because this is where vaporisation happens.
@@dirtygarageguy thanks mate 👍
With the vacuum of the piston sucking, still the chamber will only allow as much air to come in as it's volume will allow. The orifice of the intake is tiny compared to the orifice of the cylinder. Why restrict it more?
At some point you have to test your theory that it doesn’t work, you’ll learn something . do you think the engineers in formula one test their theories?
@@bsharpe Absolutely, I do this for a living. LOL
Another swing and a miss
I think their missing the point.... F1 cars. NASCAR and high performance Motorcycles use closed Air Boxes. "This is what increases air velocity" and removes back pressure. One reason they dimple the head surface and ports. They want to keep the air flow from hugging the walls. This also promotes better fuel economy. As today fuel economy means more laps per tank of fuel....And if you can go 3-4 laps more then your competitor per tank. That is equal to seconds in lead times over the course of the race...It means shit on the street...
"They want to keep the air flow from hugging the walls."
- this is called boundary layer effect - and you can't stop air from hugging anything LOL
Like hell you can't... It's why they run water injection. It cools the air charge to stop fuel from hugging the intake ports and pooling up. No to mention other benefits.. So trust me son. I had access to a flow bench on engines making 700+ HP.. You can see the difference is huge!
Good Luck
search freevalve. this is already in the making.. :-)
You mean this - ua-cam.com/video/XrYt1JHNmh4/v-deo.html
It’s logical that if you decrease the port size you reduce cylinder filling at full throttle hence losing power, like you say it’s not rocket science but I guess some people believe anything they read
So decreasing exhaust port with D shape is worst?
I don't understand how people come to dumb conclusions that make no sense. Matt saving the world one video at a time. From an engineers aspect, I enjoy your content.