What do you think about that technology? Is it robust? Isn't BMW Valvetronic better? In Valvetronic you have infinite number of lift states, here you have only two, right?
Just recently got a job at a local car shop! They're enrolling me in an Auto Technician school! I'm super excited and grateful. Hopefully I obtain as much knowledge as you guys! Keep at it!
Leaving the intake valve open longer can also increase power. Because air has mass, it also has momentum so as velocity gets near the speed of sound, assuming there's no turbo/supercharger, the air will continue to flow into the cylinder as the piston reaches BDC due to Newton's first law of motion. This means you can get more charge into the cylinder, and therefore increase power.
You can get a sense of the mass and momentum of air by blowing in a long hose and then suddenly block the flow with your tongue. Air is actually quite heavy !
hmm, but you are letting the air out into the intake manifold when leaving the intake valve open longer. That is reducing air in the cylinder -> reducing oxygen -> reducing Power. So what you are saying sounds wrong, but please correct me if I am wrong.
I believe the point is that air continues to rush into the cylinder after the piston reaches bottom dead center due to inertia, so leaving the intake valve open a little longer can bring more air in. You have to consider that things move extremely fast in an engine and it’s not just a slow moving animation or model. Flow is driven by pressure differentials so when the piston starts moving down it lowers the pressure in the cylinder even lower than the intake manifold pressure, and that’s what causes air to start flowing from the manifold into the cylinder. All through the stroke the cylinder pressure is lower than manifold pressure, and after the piston starts moving up and increasing cylinder pressure, it takes a finite amount of time and displacement before the pressure increases to above manifold pressure, causing air to be expelled back into the manifold if you keep the valve open too long.
Valve overlap is there for the very same reason (when talking about inertia) back in the carburetor days - the exhaust valve is closing but before it finishes, the intake is opening. Air with all its inertia rushing out of the exaust side pulls fresh air/fuel into the cylinder all without the piston doing anything. The important thing is "starting" the intake flow process. (This isn't needed as much anymore because of the advent of fuel injection.)
Jason, once again you're raising the bar for automotive channels. And always a great deal of valuable information presented in an easy to understand manner. Thanks for sharing your talent and time with your subscribers.
I love all the clever little mechanisms engineers come up with to get tiny percentage increases in performance. It's just endlessly fascinating. There are some really gifted people out there.
Jason I just wanna add that in turbocharged engines closing intake valves a pinch later allows to use the momentum of the compressed charge. While compression stroke begins piston is moving upward, intake cam is still opened and compressed air flowing into cyllinder meets moving piston and increases pressure. Valve should close just before air starts to flow out of cyllinder. That is called dynamic charging. Thank you for your videos man!
Actually, all this valve timing stuff is only partially for emissions. It's also in large part for efficiency. If you close the intake valve late, but keep the exhaust valve open all the way from bottom dead center to top dead center then what you wind up with is an "Atkinson cycle" in which the effective power stroke is longer than the intake stroke. This is very efficient, but not very good at making high power. Honda uses Atkinson cycle valve timing in their IMA hybrids, which is why a first generation IMA hybrid with a dead battery pack can still get 50mpg.
True, also, opening the intake valve sooner gives the intake air/mixture more time to fully fill the cilinder, this is not as important on forced induction engines but really important on naturally aspirated engines. Closing the exhaust valve a bit later will help with the maximum filling degree, as the inertia of the exhaust gasses will create underpressure in the cilinder and pull/draw fresh mixture/intake air with them into the cilinder during valve overlap. Sorry for my bad English.
@@desertrainfrog1691 Most of the time, yes, but kinda doesn’t work when using extreme lean burn. The Catalytic Converter works only within a narrow operating range,and lean burning, while technically more efficient, produces more NOx as a result.
Yep. And, OEMs will also consider the fact that most consumers will put lower octane fuel in the vehicle, so valve timings will account for that, as well (and thus sacrificing power).
I can't express my gratitude enough for you guys explaining this stuff so simply. Thanks a bunch! Now I know for a fact what VVTL-i is and how it differs from VVT-i.
My old Toyota Corolla 1800 VVti has a banging low end because of this. The bloody thing hauls up most hills with gusto in fifth, first, third, fifth no worries and hauls my jet ski like a trooper! It's a great little engine.
Hi Jason. Have you looked at the MG/Rover VVC system? It's quite interesting since it uses an eccentric gearing system that has the ability to gradually widen the valve timing as the RPM increases rather than only having the choice of two different lobes. P.S. Thanks for another great video. :) Always have to click fast! EDIT: The MG/Rover VVC system is able to control the speed of rotation of the intake cam shaft, speeding up and slowing the rotation during each revolution (it's similar to the effect that happens in universal joints that are offset at an angle). The cam lobe spends more time pressing down on the valve bucket, therefore increasing the valve open duration. It's also infinitely variable which gives the benefit of being able to tune well across the whole rev range rather than having two distinct tuning points to account for.
It's such a shame MG Rover didn't develop VVC to work on 3 cylinders - a KV6 with VVC would have been great! If Powertrain had developed a K6 / straight-six* with VGK Racing's 2.0-litre** developments and 3-cylinder VVC, MGR could have had a pair of compact 2.5-/3.0-litre six-pots with 190/230 PS on their hands. Possibly even a 2.5-litre six-cylinder turbodiesel^ too. *Cylinder block would have been about 560 mm long plus 20 mm wide timing belt plus 20 mm thick damper to make a total length of 600 mm - or 10 mm longer than a Ford / Volvo SI6. Same width and height as K4. L: 600 mm x W: 500 mm x H: 670 mm | ~150 kg **82.5 mm x 93.3 mm | 1,996cc 4cyl 16v ^The K Series was engineered to be manufactured as a diesel with an aluminium block without any further strengthening (original 75 mm bore but could could go to 77.5 mm without issue). It could have gone into the P38A, Disco II and Defender as well as the 800 and 75 - but BMW wouldn't have wanted that as it would have been in all probability more powerful and torquier than their iron-block M51D25 six-pot. | 77.5 mm x 88 mm | 2.490cc 6cyl 24v | 150 PS / 350 Nm (in 1994)
All this engineering is fascinatinf and genius. I love learning about it and want to get hands on someday when i have the time and space to rebuild a motor. But man i cant help but think, all of this engineering just for emissions? Why arent we using electric cars by now? Or hybrids? All this complicated timing and enhanced camshafts for a few extra MPG
Rover's VVC is kinda interesting too. It doesn't changes the timing but it changes the opening duration of the intake valves like this vvl does but this vvl (explained in this video) is a binary feature ( just on and off / higher and lower profile ) just like a vtec or something else. The advantage of VVC is that it's an analog feature (short opening at low rpm and long duration at high rpm).
Great video, this really broke down every question on how variable timing worked, and even answered questions I hadn't even started asking about valve lift, I appreciate it very much
That's the real lift that you feel kick in on the 2zz 6200-6500rpm til redline of 8200-8500rpm. This VVL on this VW engine is to be more efficient on the exhaust side for the turbo but it doesn't kick in yo the way that a VVTLi or VTEC does
"Variable" is more "2-stage" valve lift in this case. BMW's Valvetronic has true variable valve lift by adding another shaft and using a stepper motor. Still good video explaining the benefits.
I think u forget one point. Why we close intake valve late? At very high rpm (say 6000), at such a high speed inertia of air comes into picture. After the end of the suction stroke, piston starts moving back towards valves (compression stroke). As piston appears like compressing the air, but at the same time due to inertia of the air, it is still filling the chamber. effectively we get more volumetric efficiency.
With Koenigsegg Freevalve you have 100% full control of the heights, how long they are going to be open and shut, timing etc etc! It is much more efficient and you make more power! It is like built up by these electro magnets if I remember correctly..
You both are good, but together it does get pretty cool. Reminds me of the last couple seasons of Highlander. When I learned two of the characters were great friends in real life, it showed their friendship better on the set.
i learned about this only after a rocker arm came loose and distroyed my camshaft.Had to open it and i only had problems on high lift.Great video overall
thom1218 it's an Audi engine first, VW gets the hand me downs not the other way around. I think you are confusing the diesel scandal with this gas engine as well.
The editing was very well done Jason! We get to listen and take a closer look at what you are talking about. Also, its always great to watch you two together
Opening the intake valve early will also reduce pumping loss by ensuring that the combustion residual air that is rushing out via the exhaust port creates a suction force in the cylinder that pulls the fresh charge from the intake port while the intake valve is gradually opening up.
One thing they forgot to mention is that when the engine changes de intake cam timming is also changing the LSA angle (in this case because is a DHOC) and a wider LSA improves smother idle but when you need power the VVT closes that angle improving combustion
In fact, when accelerating or decelerating every cylinder is gets his ignition on a different rpm. For optimal results, every cylinder needs his own camshaft. The VVC of a Rover K motor has a control unit on each side of the motor with 2 camshafts. The second runs in the inside of the first.
My 1.8 Supercharged Toyota Corolla has both, VVTL-I. Lift on both exhaust and intake valves which kicks in at 5.2K to redline at 8.2K, and variable valve timing on the intake cam shaft.
Actually, this tech works - as opposed to the TDI exhaust scam which they did on purpose. It works mostly because the Volkswagen engineers simply ripped off the japanese Honda VTEC design from back in the early 90's and adapted it to their needs.
Patent law is a very complicated thing and differs from nation to nation. And depending on where your patent was registered, it is possible to rip off a patented design and adapt it just a bit so it can be labeled as a new design in the eyes of the law. And you are right: the PRC doesn't give two shits about other countries' intellectual property. They are very strict in their own country when it comes to foreign products, though. They just recently ruled that Volkswagen had to extend the warranty period for their 7-speed dual-clutch transmissions to 10 years because of the various design flaws and problems with it.
Rover's VVC is interesting too. It involves using oil pressure to move a secondary lobe that lifts the whole cam profile when needed to provide a flatter torque curve. It can do it I think quicker than about a 1/4 of a revolution of the cam so you can even control the lift before the valve has finished closing or opening.
super interesting video. i have a 2015 gti as well as a 240sx with an rb25 so both of my cars utilize VVL. whats really interesting to me is how much more advance and complex the gti handles it compared to the rb25. amazing how far technology as come.
A solenoid pushing a sleeve back and forth is over engineered? it's not like using oil pressure to rotate the camshaft gear like in the intake side or Vtec, is it now?
In the vtec, theres no solenoil, just oil pressure that push a sleeve and lock the rocker together so the intake valve open more and longer. Theres no solenoil pushing sleeve ON the cam and everything. Always remember : the more moving pieces an engine have, the less reliable that engine will be.
thefatdindon it's pretty obvious how Vtec works and that's exactly what I said in my comment : "it's not like using oil pressure to rotate the camshaft gear like in the intake side or Vtec" My point is using oil to rotate isn't really that different to a solenoid pushing a sleeve and the solenoids are much easier to maintain since you can just unbolt them from the cylinder-head cover, good luck with Vtec and removing the whole engine side and the timing chain. But what do I know I'm just an engineer. hopefully not all people are scared of new or more complex stuff otherwise we'll be stuck with cars with no steering assist or ABS for the very least.
if you guys want to see how VVT makes a hell of a difference between a normal engine look up HKS RB26 V-CAM it pretty much giving the RB26DETT with VVT making it RB26VETT The engine pick up is impressive!
Was always curious how they got rid of the egr valve... Thanks :-) It amazes me that they can so complicate these engines, and still get them to last for so many miles!!! 50 years ago, you were lucky if you got 100k out of a engine!!! Thanks for the explanation Mr Engineering Explained :-)
Material science, computer science and experience in engineering. Not to mention the 100+ years to refine. Metallurgy, lubrication chemistry, computer system control, precision manufacturing techniques. ALL highly developed fields in their own right. ICE has probably the longest running and most interdisciplinary effort into it than anything else other than the field of human medicine. But the irony may be that it will ultimately be replaced by another long time technology - the electric motor.
VVT got another advantage in power. During high rpm the gas-air-mix is going in the cylinder with high speed (due to the higher pumping effect of the fast moving piston), and because of this you can keep the intake valve open even when the piston starts to move up, because it first needs to decelerate the incoming air, before it can push the gas-air-mix through the open valve out of the cylinder (what you don't want of course, but this would if the valve keeps open later during low rpms, because the air isn't travelling with high velocity). So you get more gas in the cylinder, got therefore a higher compression and a higher amount of fuel, and finally more power.
Hi! Nice explanation! At 8.07 min you can see that the shafts of the valves are bent. Please, confirm that this is due to a collision with the pistons and not some fancy valve and cylinder head design. THX!
Your answers why open/close the valves early/late is a general explanation, but there are exceptions to those rules. My 2010 Yamaha R6 made lots more power when we closed the intake valves earlier. I assume because it got more compression ? Just a theory.
IF you close the intake valves late when the air is moving quickly, it you can fill the cylinder more than 100% because the airs forward momentum it wont leak back out as the Piston starts moving back up
7:20 you say that closing the intake valve early means you're pulling less vacuum, but the vacuum in the cylinder is going to be even higher with them closed than if they could draw from the mani. If it reduces pumping losses I would assume the improvement is due to lower cylinder pressure on the compression stroke.
Just watched this and one by "Pawinning" re how VVL and VANOS systems work> They both make me want a straight-up old-timey engine, where none of the forces are helical. Orthogonality for the win!
Hey Guys, great Video on showing the mechanics. You haven't mentioned the real reasons for changing the timing. Such as on engines that are not "NA" or for exhaust scavenging or both. It really depends on your engine setup and application.
on your last video I asked if you guys could get real car parts in these vids to actually show off what u were talking about while u explain it and in this one you really did, I don't know if that was on purpose or not but thank you!!!! =) I deff liked this set-up alil better then the whiteboard. A very good video btw, thanks for the info
As I understand it, some engine brakes on trucks will open the exhaust during combustion so that the engine is compressing the air but getting no actual power out of it, netting a negative torque (from the perspective of going forward).
closing the intake valves later may do that but in performance engines what it does is taking advatage of the intake fuel mixtures flow speed and even though the piston starts to go up just a little more fuel goes in the combustion chamber so you make more power.(if i'm corect this applies to both n/a and forced induction engines)
i think the reason for the late closing of intake valve is to use the inertia of intake gases in order to suck in more air fuel mixture even after the piston starts to move away from BDC
Rock on man. Thanks for coming and hanging out. It's always a fun time collaborating with ya.
What do you think about that technology? Is it robust? Isn't BMW Valvetronic better? In Valvetronic you have infinite number of lift states, here you have only two, right?
It is pretty reliable. We have seen a few solenoid failures, but nothing crazy.
HumbleMechanic But vtec is only at high rpm. My car starts after 4K as well, not like it's better than a better engine.
Leo you'd be going from belt driven to chain driven. Better off swapping the whole engine.
Buuuuuuutttttttt don't let me stop you from trying.
You have the beard of a Greek God
Just recently got a job at a local car shop! They're enrolling me in an Auto Technician school! I'm super excited and grateful. Hopefully I obtain as much knowledge as you guys! Keep at it!
Go watch the beginning of his very first video from 5 years ago, then click over to this. Insane how far you've come man!
i'm so glad this channel exists
Leaving the intake valve open longer can also increase power. Because air has mass, it also has momentum so as velocity gets near the speed of sound, assuming there's no turbo/supercharger, the air will continue to flow into the cylinder as the piston reaches BDC due to Newton's first law of motion. This means you can get more charge into the cylinder, and therefore increase power.
You can get a sense of the mass and momentum of air by blowing in a long hose and then suddenly block the flow with your tongue. Air is actually quite heavy !
Yess thats were CVVD comes into the picture. Hyundai made the first production car with the technology!
hmm, but you are letting the air out into the intake manifold when leaving the intake valve open longer. That is reducing air in the cylinder -> reducing oxygen -> reducing Power. So what you are saying sounds wrong, but please correct me if I am wrong.
I believe the point is that air continues to rush into the cylinder after the piston reaches bottom dead center due to inertia, so leaving the intake valve open a little longer can bring more air in. You have to consider that things move extremely fast in an engine and it’s not just a slow moving animation or model. Flow is driven by pressure differentials so when the piston starts moving down it lowers the pressure in the cylinder even lower than the intake manifold pressure, and that’s what causes air to start flowing from the manifold into the cylinder. All through the stroke the cylinder pressure is lower than manifold pressure, and after the piston starts moving up and increasing cylinder pressure, it takes a finite amount of time and displacement before the pressure increases to above manifold pressure, causing air to be expelled back into the manifold if you keep the valve open too long.
Valve overlap is there for the very same reason (when talking about inertia) back in the carburetor days - the exhaust valve is closing but before it finishes, the intake is opening. Air with all its inertia rushing out of the exaust side pulls fresh air/fuel into the cylinder all without the piston doing anything. The important thing is "starting" the intake flow process. (This isn't needed as much anymore because of the advent of fuel injection.)
VVL just kicked in YO!..... doesn't sound the same as VTEC. Or Vee Vee TEE BABY! Good explanation guys!
3:46 lol
In the Celica we just call it lift, even though its both. Hahaha. Hitting lift is always fun.
I was completely lost due to the lack of a white board and many many different coloured pens ;-)
Your are a subscriber, I surmise.
😂😂😂
Jason, once again you're raising the bar for automotive channels. And always a great deal of valuable information presented in an easy to understand manner. Thanks for sharing your talent and time with your subscribers.
Ff
I love all the clever little mechanisms engineers come up with to get tiny percentage increases in performance. It's just endlessly fascinating. There are some really gifted people out there.
I know it's not always possible but more videos where you show the actual parts would be awesome.
Just had a discussion with a mechanic about these same two topics: VVL against VVT, now I have this video to my assistance.
Thank you guys so much.
Jason I just wanna add that in turbocharged engines closing intake valves a pinch later allows to use the momentum of the compressed charge. While compression stroke begins piston is moving upward, intake cam is still opened and compressed air flowing into cyllinder meets moving piston and increases pressure. Valve should close just before air starts to flow out of cyllinder. That is called dynamic charging. Thank you for your videos man!
Actually, all this valve timing stuff is only partially for emissions. It's also in large part for efficiency. If you close the intake valve late, but keep the exhaust valve open all the way from bottom dead center to top dead center then what you wind up with is an "Atkinson cycle" in which the effective power stroke is longer than the intake stroke. This is very efficient, but not very good at making high power.
Honda uses Atkinson cycle valve timing in their IMA hybrids, which is why a first generation IMA hybrid with a dead battery pack can still get 50mpg.
True, also, opening the intake valve sooner gives the intake air/mixture more time to fully fill the cilinder, this is not as important on forced induction engines but really important on naturally aspirated engines. Closing the exhaust valve a bit later will help with the maximum filling degree, as the inertia of the exhaust gasses will create underpressure in the cilinder and pull/draw fresh mixture/intake air with them into the cilinder during valve overlap. Sorry for my bad English.
@@Herbsy420 : True. And I found your English perfectly intelligible, so no apology needed.
Efficiency and Emissions are very much related though? The more miles per gallon we get, the less emissions per mile.
@@desertrainfrog1691
Most of the time, yes, but kinda doesn’t work when using extreme lean burn. The Catalytic Converter works only within a narrow operating range,and lean burning, while technically more efficient, produces more NOx as a result.
Yep. And, OEMs will also consider the fact that most consumers will put lower octane fuel in the vehicle, so valve timings will account for that, as well (and thus sacrificing power).
Bravo sir, very well explained and glad you had visuals instead of the board to explain.
I can't express my gratitude enough for you guys explaining this stuff so simply. Thanks a bunch! Now I know for a fact what VVTL-i is and how it differs from VVT-i.
This is so cool, and when you run specific emissions test you can run it in a way that it always provides lowest NOx emission.
Almost like cheating lol
My old Toyota Corolla 1800 VVti has a banging low end because of this. The bloody thing hauls up most hills with gusto in fifth, first, third, fifth no worries and hauls my jet ski like a trooper! It's a great little engine.
Hands down this is the best video I have seen on VVL and VVt, thank you.
Hi Jason. Have you looked at the MG/Rover VVC system? It's quite interesting since it uses an eccentric gearing system that has the ability to gradually widen the valve timing as the RPM increases rather than only having the choice of two different lobes.
P.S. Thanks for another great video. :) Always have to click fast!
EDIT: The MG/Rover VVC system is able to control the speed of rotation of the intake cam shaft, speeding up and slowing the rotation during each revolution (it's similar to the effect that happens in universal joints that are offset at an angle). The cam lobe spends more time pressing down on the valve bucket, therefore increasing the valve open duration. It's also infinitely variable which gives the benefit of being able to tune well across the whole rev range rather than having two distinct tuning points to account for.
It's such a shame MG Rover didn't develop VVC to work on 3 cylinders - a KV6 with VVC would have been great! If Powertrain had developed a K6 / straight-six* with VGK Racing's 2.0-litre** developments and 3-cylinder VVC, MGR could have had a pair of compact 2.5-/3.0-litre six-pots with 190/230 PS on their hands. Possibly even a 2.5-litre six-cylinder turbodiesel^ too.
*Cylinder block would have been about 560 mm long plus 20 mm wide timing belt plus 20 mm thick damper to make a total length of 600 mm - or 10 mm longer than a Ford / Volvo SI6. Same width and height as K4. L: 600 mm x W: 500 mm x H: 670 mm | ~150 kg
**82.5 mm x 93.3 mm | 1,996cc 4cyl 16v
^The K Series was engineered to be manufactured as a diesel with an aluminium block without any further strengthening (original 75 mm bore but could could go to 77.5 mm without issue). It could have gone into the P38A, Disco II and Defender as well as the 800 and 75 - but BMW wouldn't have wanted that as it would have been in all probability more powerful and torquier than their iron-block M51D25 six-pot. | 77.5 mm x 88 mm | 2.490cc 6cyl 24v | 150 PS / 350 Nm (in 1994)
All this engineering is fascinatinf and genius. I love learning about it and want to get hands on someday when i have the time and space to rebuild a motor. But man i cant help but think, all of this engineering just for emissions? Why arent we using electric cars by now? Or hybrids? All this complicated timing and enhanced camshafts for a few extra MPG
Rover's VVC is kinda interesting too. It doesn't changes the timing but it changes the opening duration of the intake valves like this vvl does but this vvl (explained in this video) is a binary feature ( just on and off / higher and lower profile ) just like a vtec or something else. The advantage of VVC is that it's an analog feature (short opening at low rpm and long duration at high rpm).
Great video, this really broke down every question on how variable timing worked, and even answered questions I hadn't even started asking about valve lift, I appreciate it very much
He looks like the guy that reads the terms and conditions
He looks like the guy that _writes_ the terms and conditions.
He _is_ the terms and conditions...
... Lots of information inscribed in that human brain of his...
I agreed
Terms and Conditions.
😂🤣😂. Correct!!
This is cool, my Celica has VVTL-i, with timing and lift on both the intake and exhaust camshafts.
And the cams don't slide on the shaft, and no actuator pins, so there's actually less risk of a catastrophic failure.
It needed VVL on the intake cam because it’s not forced induction
That's the real lift that you feel kick in on the 2zz 6200-6500rpm til redline of 8200-8500rpm. This VVL on this VW engine is to be more efficient on the exhaust side for the turbo but it doesn't kick in yo the way that a VVTLi or VTEC does
"Variable" is more "2-stage" valve lift in this case. BMW's Valvetronic has true variable valve lift by adding another shaft and using a stepper motor. Still good video explaining the benefits.
I think u forget one point. Why we close intake valve late?
At very high rpm (say 6000), at such a high speed inertia of air comes into picture. After the end of the suction stroke, piston starts moving back towards valves (compression stroke). As piston appears like compressing the air, but at the same time due to inertia of the air, it is still filling the chamber. effectively we get more volumetric efficiency.
With Koenigsegg Freevalve you have 100% full control of the heights, how long they are going to be open and shut, timing etc etc! It is much more efficient and you make more power!
It is like built up by these electro magnets if I remember correctly..
I like this combo! Very good guys.
THANKS :)
So how long before you guys go FULL ZZ TOP with the beards?
Jason I don't think will ever. LOL
You both are good, but together it does get pretty cool. Reminds me of the last couple seasons of Highlander. When I learned two of the characters were great friends in real life, it showed their friendship better on the set.
This is probably one of the most interesting videos ive watched on this channel! Very informative.
just read title, haven't seen video, already know it's gonna be goooood
i learned about this only after a rocker arm came loose and distroyed my camshaft.Had to open it and i only had problems on high lift.Great video overall
I was always fascinated by this subject ever since I learned about Honda's VTEC system. Cue the "vtec kicked in" jokes.
Emissions control on a VW engine - LOL.
How does it know it's being tested?
thom1218 it's an Audi engine first, VW gets the hand me downs not the other way around. I think you are confusing the diesel scandal with this gas engine as well.
Is´nt it an EA888?
@@dcxSpartan117 audi and vw are part of the same group, just targeting different segments
My Ford 5.4L - 3V is known to have VVT issues, mine seems OK. Thank you for making the video!
The editing was very well done Jason! We get to listen and take a closer look at what you are talking about. Also, its always great to watch you two together
Opening the intake valve early will also reduce pumping loss by ensuring that the combustion residual air that is rushing out via the exhaust port creates a suction force in the cylinder that pulls the fresh charge from the intake port while the intake valve is gradually opening up.
You guys are such good teachers. I now know how VVT works, why it exists and what it all looks like.
This is actually amazing that they use both types of valve technology
Keep the video short. Straight to the point. This video can be done in less than 5 minutes
My understanding of closing the intake valve later at high RPMs was to allow the momentum of the incoming fuel/air charge to help load the cylinder.
One thing they forgot to mention is that when the engine changes de intake cam timming is also changing the LSA angle (in this case because is a DHOC) and a wider LSA improves smother idle but when you need power the VVT closes that angle improving combustion
Always thoroughly impressed with how detailed yet easy to understand your videos are! Very informative!
Cool to see two of my favorite UA-camrs collaborating like this. Please do more of these videos! Thanks for all the work that both of you do!\
Josh Gawrick thanks Josh
I prefer my way, Huge duration, high idle.
Good job, Jason, the picture for this video is so good, that I watched it for a few more minutes a second time. :)
Great video, my new car has vvt so it's awesome to have a full demonstration of how it works. Thanks!
Koenissegg has the best valve train anyway. I think it's amazing, like having a different "cam" optimised for the rpm and load that you are at!
These are my favorite types of videos. Love the explanations. Great work!
Was excited to see Charles on here.
In fact, when accelerating or decelerating every cylinder is gets his ignition on a different rpm. For optimal results, every cylinder needs his own camshaft. The VVC of a Rover K motor has a control unit on each side of the motor with 2 camshafts. The second runs in the inside of the first.
My 1.8 Supercharged Toyota Corolla has both, VVTL-I. Lift on both exhaust and intake valves which kicks in at 5.2K to redline at 8.2K, and variable valve timing on the intake cam shaft.
Funny to hear about NOx emissions in association with VAG. That's awesome German trickery for sure!
Actually, this tech works - as opposed to the TDI exhaust scam which they did on purpose. It works mostly because the Volkswagen engineers simply ripped off the japanese Honda VTEC design from back in the early 90's and adapted it to their needs.
Sven. No tech stays patented for the company that invented it. Especially to the Chinese. They respect no one's ownership over technique.
Patent law is a very complicated thing and differs from nation to nation. And depending on where your patent was registered, it is possible to rip off a patented design and adapt it just a bit so it can be labeled as a new design in the eyes of the law. And you are right: the PRC doesn't give two shits about other countries' intellectual property. They are very strict in their own country when it comes to foreign products, though. They just recently ruled that Volkswagen had to extend the warranty period for their 7-speed dual-clutch transmissions to 10 years because of the various design flaws and problems with it.
Sven Schwingel great comment. :)
CMac oppooooooooooopooooooooooooopooppoooppoooooooopooooooooopoooooooooo
Rover's VVC is interesting too. It involves using oil pressure to move a secondary lobe that lifts the whole cam profile when needed to provide a flatter torque curve. It can do it I think quicker than about a 1/4 of a revolution of the cam so you can even control the lift before the valve has finished closing or opening.
super interesting video. i have a 2015 gti as well as a 240sx with an rb25 so both of my cars utilize VVL. whats really interesting to me is how much more advance and complex the gti handles it compared to the rb25. amazing how far technology as come.
That is a cool duo of cars!
thank you!! :)
That exhaust cam looks like some seriously over-engineered and expensive VTEC!
UndergroundTrev VTEC=VeryTallEngineCoolant
UndergroundTrev designed by Germans, what do you expect?
A solenoid pushing a sleeve back and forth is over engineered? it's not like using oil pressure to rotate the camshaft gear like in the intake side or Vtec, is it now?
In the vtec, theres no solenoil, just oil pressure that push a sleeve and lock the rocker together so the intake valve open more and longer. Theres no solenoil pushing sleeve ON the cam and everything. Always remember : the more moving pieces an engine have, the less reliable that engine will be.
thefatdindon
it's pretty obvious how Vtec works and that's exactly what I said in my comment :
"it's not like using oil pressure to rotate the camshaft gear like in the intake side or Vtec"
My point is using oil to rotate isn't really that different to a solenoid pushing a sleeve and the solenoids are much easier to maintain since you can just unbolt them from the cylinder-head cover, good luck with Vtec and removing the whole engine side and the timing chain.
But what do I know I'm just an engineer. hopefully not all people are scared of new or more complex stuff otherwise we'll be stuck with cars with no steering assist or ABS for the very least.
you guys make this stuff so entertaining.
So that's how they accomplish those functions! Thanks! Those clever engineers!
GREAT video! Visuals were perfect, much needed
Great info, but the video quality was some of your best. I would like to see this video quality in future videos.
I just bought a 2015 GTI so this was really helpful, thanks guys
if you guys want to see how VVT makes a hell of a difference between a normal engine
look up HKS RB26 V-CAM
it pretty much giving the RB26DETT with VVT making it RB26VETT
The engine pick up is impressive!
Was always curious how they got rid of the egr valve... Thanks :-)
It amazes me that they can so complicate these engines, and still get them to last for so many miles!!! 50 years ago, you were lucky if you got 100k out of a engine!!!
Thanks for the explanation Mr Engineering Explained :-)
Material science, computer science and experience in engineering. Not to mention the 100+ years to refine. Metallurgy, lubrication chemistry, computer system control, precision manufacturing techniques. ALL highly developed fields in their own right. ICE has probably the longest running and most interdisciplinary effort into it than anything else other than the field of human medicine. But the irony may be that it will ultimately be replaced by another long time technology - the electric motor.
Note to everyone: the exhaust lobes are also on different geometry aka: it's a two-stage oldschool vvt and vvl
VVT got another advantage in power. During high rpm the gas-air-mix is going in the cylinder with high speed (due to the higher pumping effect of the fast moving piston), and because of this you can keep the intake valve open even when the piston starts to move up, because it first needs to decelerate the incoming air, before it can push the gas-air-mix through the open valve out of the cylinder (what you don't want of course, but this would if the valve keeps open later during low rpms, because the air isn't travelling with high velocity). So you get more gas in the cylinder, got therefore a higher compression and a higher amount of fuel, and finally more power.
Thanks i finally understand what VVT and VVL is about. Nice
Hi! Nice explanation! At 8.07 min you can see that the shafts of the valves are bent. Please, confirm that this is due to a collision with the pistons and not some fancy valve and cylinder head design. THX!
Your answers why open/close the valves early/late is a general explanation, but there are exceptions to those rules. My 2010 Yamaha R6 made lots more power when we closed the intake valves earlier. I assume because it got more compression ? Just a theory.
thanks for coming the work shop and wellcome
IF you close the intake valves late when the air is moving quickly, it you can fill the cylinder more than 100% because the airs forward momentum it wont leak back out as the Piston starts moving back up
Two very smart and funny guys, great video
Great video. The use of props and parts really help illustrating the concept. Thanks
You should get in touch with Koenigsegg and take apart one of their Freevalve systems. That would be awesome
Only cool if they actually get their technology out for consumer but until then freevalve is just vapor ware at this point
7:20 you say that closing the intake valve early means you're pulling less vacuum, but the vacuum in the cylinder is going to be even higher with them closed than if they could draw from the mani. If it reduces pumping losses I would assume the improvement is due to lower cylinder pressure on the compression stroke.
Thank you Jason. Now I understand Variable Cam timing a little better. Although your whiteboard would have helped.
Just watched this and one by "Pawinning" re how VVL and VANOS systems work>
They both make me want a straight-up old-timey engine, where none of the forces are helical.
Orthogonality for the win!
To explain this better we have Charles. Proceeds to tell Charles exactly what's going on for about 9mins out of the 9:46 video lol. Good video though
congrats on one mil
My 93 Nissan Sentra Se-R SR20VE Neo VVL for the Win😎
Very interesting and complex setup. Quite a bit of adjustment on the intake cam gear. Thank you for posting and sharing this.
Nissan's NEO VVL is insane. BEAST!
Cool and informative collaboration video
Awesome video! You both always explain beautifully how cars work.
Again. Excellent explanation. Thanks. Knowledge is power. Well ...maybe duration is...or lift...
Please do a video on 5 things not to do with a diesel/ turbo diesel car. Also maybe one with 5 tips for first time diesel buyers
Steven B Easy, don't buy one
Steven B tip no 1: make sure it doesn't smoke
Best 10min ever spend ! and which car engine is that ?? Audi, VW ??
Yathu prem from an 09 Audi.
Vag
Great on hands explinantion. You guys make a great educational team.
My respect for that mechanic and the “Audi” engineers , i have nothing against technology; but I prefer simple so I can fix it myself.
Hey Guys, great Video on showing the mechanics. You haven't mentioned the real reasons for changing the timing. Such as on engines that are not "NA" or for exhaust scavenging or both. It really depends on your engine setup and application.
on your last video I asked if you guys could get real car parts in these vids to actually show off what u were talking about while u explain it and in this one you really did, I don't know if that was on purpose or not but thank you!!!! =) I deff liked this set-up alil better then the whiteboard. A very good video btw, thanks for the info
Nice collaboration
You guys are killer at relating information, thank you 👍
always good to see such a collaboration :D
Timing belt Volkswagen gasoline 1.2 I am waiting for a video about this Thank you bro
""""Excellant video , well explained , great to hear people that know what they are talking about thank you both ."""
There were surprisingly so many awkward moments haha
But great content thanks!
As I understand it, some engine brakes on trucks will open the exhaust during combustion so that the engine is compressing the air but getting no actual power out of it, netting a negative torque (from the perspective of going forward).
closing the intake valves later may do that but in performance engines what it does is taking advatage of the intake fuel mixtures flow speed and even though the piston starts to go up just a little more fuel goes in the combustion chamber so you make more power.(if i'm corect this applies to both n/a and forced induction engines)
My ‘16 GTI has VVT on both cams and VVL on exhaust. Different years of this 2L engine seem to have different combinations of VVT and VVL.
i think the reason for the late closing of intake valve is to use the inertia of intake gases in order to suck in more air fuel mixture even after the piston starts to move away from BDC
Super interesing! More vids like this please!