When I re-discovered this channel after watching colin furze a couple days ago deadass thought you were him and had just found his old channel! Lol you guys could be brothers
as an 80;s 2t fan i didn't really understand how critical the actual exhaust design was to the way a2t ran,after watching this vid i now know and understand what a genius the likes of Stan Stephens were.
Good bit about ram air- the actual positive pressure generated by "ramming" air into an intake tract is extremely low. . .and does very little to help cylinders fill at speeds below 160mph :)
Love the rants they are top notch ,this guy is a genius I wish more people had an actual knowledge of whats going on inside the engine and not how to replace a component.Im 16 and I drive a self-destroying kx125 and loving it .Just cant beat a power ban.Besides you should sell a 2 stroke before u ever have it long enough to need rings even .
thanks for the like matt s you can tell this is my way of agreeing with you and like you not understanding how folk don't seem to understand the basics
Oh look, what's Matt doing? Bust'n chops again? Good, good. Anyway, love the videos, especially now since I bought myself a 2 stroke (never owned one before - it's a neat toy).
When you were talking about the trapped exhaust all that came to mind were old Detroit diesels, of course it's a complete oddball in its own right but still very interesting when looking into 2 strokes.
Diesel 2 strokes our far from odd balls and are and have been threw out the years very common and popular. Almost Every train in the world have a 2 stroke Diesel powering them since steam went obsolete.
Right. For fucks sake, you run quite a mouth on ya, lad!!! Thing is - you're 115% CORRECT. The pressure differential that causes the fuel in the Crankcase to be shoved up the Transfer Ports when the Bloody Piston is driven down... Is NOT fuckin' SUPERCHARGING!!! For fuks sake! I've been building Race Engines for Decades, and STILL have that insane debate!!! I'm enjoying your Videos mate! You TELL it like it is, and cut straight through the bullshit!
hi I have been watching your vids for a little more than a month now it's good to see some real no bull educational stuff keep up the good work NB minarelli 50cc race bike from 1960s was it good or shite
Opposed piston 2 strokes are great for efficiency and have a lot of power potential. Uniflow is the most positive form of cylinder scavenging and OP is a good way to do it. Here's an opposed piston multifuel 2 stroke with a blower and a turbo... ua-cam.com/video/UxON-HIlz5E/v-deo.html
Matt Matt Matt ,, what have I already told you? You'd have more luck with that wall. It's like you're talking to yourself ,, oh hang on ,, you actually are ,, hahaha
Not quite 2 stroke related, but might be one for the list because it's all about pressure waves , that fancy Opel Comprex System they used on their Diesels back in the 80s.
surely a supercharger works at all RPM and ram air only becomes effective when the engine/bike reaches and goes above a certain speed creating the a similar effect to forced induction
I live in Idaho U.S and these FOCKIN PLANES! every day over my house like if we dont keep flying these fighter jets overhead maybe the Native Americans might come back or something,(sarcasm) and then I get a ticket for having loud exhaust on the car I pay taxes on! Great video keep it up.
OK, here's the thing. The crank case isn't really pressurised. Not much anyway. Most "modern" two strokes have about 3 times the volume in the crank case as in the cylinder (a 125cc engine would have about 350-380cc crank case volume). So when the piston is at BDC vs TDC, the mixture in the crank case has hardly compressed at all (it's only about 1:3) compared with the combustion chamber (10:1) which goes from about 125cc down to 10-15cc so there's really stuff all compression in the crankcase. When the transfer port first opens, the pressure in the cylinder is higher than in the transfer duct so it actually blows a little into the transfer. Then the momentum of the exhaust gasses rushing out the exhaust port starts to pull the air/fuel mix into the cylinder. The pressure at this point in the transfer duct is lower than 1 bar so it must be sucking the mixture, not blowing it. This especially true when the engine is on the pipe (in the powerband) where the expansion chamber is working its best. That's one of the reasons a two stroke will run like crap without a decent pipe. It's not just the pressure wave forcing the mix back into the cylinder before the exhaust port closes. But as you say, it's bloody complex and it's certainly not supercharged.
"pull the air/fuel mix into the cylinder." - lol pull "the pressure in the cylinder is higher than in the transfer" - exhaust port opens first "The pressure at this point in the transfer duct is lower than 1 bar so it must be sucking the mixture, not blowing it" - don't get this bit "It's not just the pressure wave forcing the mix back into the cylinder before the exhaust port closes." - so what is it?
Matt, I've taken a closer look at the data I have and I have to admit, I'm wrong on a couple of things. I'm looking at data for a Honda RS125 GP engine so everything below is in reference to that. As you said, the air/fuel mix is in fact mostly forced into the cylinder by crankcase pressure. There is a part of that process where the pressure at the transfer port is less than 1 bar but that's just as the transfer port is closing. Most of the flow into the cylinder is under positive pressure as you said. But, when the transfer port first opens, the pressure in the cylinder is still higher than the crankcase and there's a moment where some exhaust gasses are forced into the transfer port. Then as the pressure inside the cylinder rapidly reduces, the crankcase pressure pushes those exhaust gasses back into the cylinder along with the air/fuel mix. In an RS125 engine, the crankcase pressure never goes above about 1.5 bar so my point remains on how low that pressure is compared with whats going on in the cylinder. So until the cylinder pressure gets below 1.5 bar, the air/fuel mixture cannot enter the cylinder. Anyway, the point I'm making is that I didn't get all my facts straight before. Sorry about that.
Chris you where right first time, the depression caused by the expansion chamber 'pulls' the mixture thru the transfers. Your note on the higher pressure in the cylinder on transfer port opening causing reverse flow in the transfer passages is also correct.
So first it was your mate sticking his foot in the lift door and now it's toothpaste!👍🏻👏 How about a small opening just below the squish in the head and a chamber for the trapped exhaust to be pushed into?
chris davidson When the exhaust port is cleared it empties out the cylinder head into the exhaust.Anything to give a nice fresh mixture around the spark plug? I'm sure there would be a problem with it,detonation,carbon?
hmmm... i was thinking that it'd get stuck in the chamber, as if the exhaust gas gets trapped against the head, how's it going to get back out of the chamber?
This is the problem when trying to explain the dynamics of a tuned pipe equipped 2 stroke. The reverse pulse wave from the pipe packs in more pressure just as the piston is closing the port. No-one should say that it's supercharged. But rather to the lay person, it is a "supercharge effect" as in pressurizing the chamber. But ONLY at the sweet spot of RPM when the reverse pulse reaches the closing exhaust port at just the right time. We are not preaching to the choir, we are trying to explain to the guys that have never been to church. A static adjustable length header section on the pipe, can change the distance from the convergent cone to the exhaust window, and that will change the timing of that reverse pulse. That adjusts the point of the sweet spot, or the supercharge EFFECT, or hitting the pipe. That is how you can TUNE your tuned pipe.
Yamm had angled transfer ports to go out it a y shape and the boost port helps sandwich exhaust gases out. Sorry for short analogy but that's it in short.
the thumbnail shows it but i kinda missed hearing that todays 2T use the schnuerle porting and how the flow looks there ;-) but it says part one so this'll be said im sure
I wonder if the orignal designers of 2 strokes knew that fuel could come back in the combustion chamber, or was that figured out later on in developement? The 2 strokes I grew up riding ('73 Yamaha GT80,MX100) didn't have expansion chambers. At least I don't think they did. The large expansion chamber with a very narrow stinger seems to have come about in the mid 70's.
Supercharging is defined as a volume of gas trapped in a cylinder that is greater than that if the trapped volume was freely allowed to occupy the cylinder at the same temp and atmo pressure, no matter how that greater trapped volume was achieved
There are and has only been 3 production 'supercharged' bikes - fitted with superchargers - Kawasaki H2 and H2R - Peugeot Jetforce Compressor - Vyrus 987 C3 - BMW Type 255 (was a race bike - not production) Seen as though Kawasaki made the statement that this is the only supercharged production bike availible then you need to tell kawasaki they are wrong.
Impossible to supercharge a conventional two-stroke engine with symmetrical port timing. Supercharge in any two-stroke requires the exhaust port to close well before the transfers do.
How do you supercharge when all the incoming charge blows through the cylinder during the scavenging process and straight into the exhaust pipe? You need to charge a closed cylinder under positive pressure to achieve any increase in mass charge. The charge pressure in a two-stroke is equal to the exhaust back pressure because the exhaust remains open after the transfers close.
"How do you supercharge when all the incoming charge blows through the cylinder during the scavenging process and straight into the exhaust pipe?" - the 'force' of the returning pressure wave is proportional to the combustion in the cylinder. You have a supercharged engine so the pressure wave has a higher energy. Granted you have to match the exhaust to the system but it can be done. I did a video called 'can you turbocharge a 2 stroke. This isn't supercharging but the principle is the same.
You said yourself that the reverse pressure wave was not true supercharging! You would need to have further charge mass entering the cylinder as the reverse wave is having its effect and this would occur at only a very narrow range of rpm as it relies purely on resonance.
Turbocharging and supercharging are different animals... Turbo creates back pressure proportional to the charge pressure so it works even if the exhaust port closes after the transfer port... with supercharging you can't raise the volume / pressure in the cylinder because the exhaust is still open to the atmosphere after the transfer port closes.
They use systems in cars to recover exhaust gases and useing them in the next cycle, so they can lower the emissions.I think its to lower the burning temperature and so reducing NO emissions(in diesel engines also the unburned carbon particles). For me it makes sense to build such a system for diesel engines but does it also makes sense for gasolin engines. Just asking because of those 15% exhaust gas in the chamber.
CAT has a thing called ACERT that does EGR internally with valves.... By nature most 2 strokes have some exhaust gas in the mix at the time of combustion. Exhaust gases lower the peak combustion temperature reducing the formation of NOX.
The Workshop I have another idea for 2 strokes make like a compression chamber out side of the motor by taking exhaust pressure and using that or something of that sort I'm not saying that it would work but it might
I agree it is not supercharged, however, if the crankcase was not pressurizing the crankcase, the engine in your example wouldn't run very well, maybe not at all. Also, a 4 stroke doesn't use the crankcase pressure to force air and fuel into the intake, so a simple 2 stroke is obviously getting something more than a 4 stroke is. Yes, most* 2 stroke's natural design is to use this crankcase pressure, but that still doesn't negate that it is forced induction of some sort, to some degree. Still, I agree, NOT supercharged.
If you take away a supercharger from an engine, it's still an engine and it still runs. You take away crankcase pressure variations from a 2T, it's no longer an engine because it doesn't run. It's not supercharging, it's called inherent 2T design function.
KillerWattsRacing Right there with you, totally agree. I do think you will also agree that 2T design function INCLUDES forcing air into the combustion chamber from crankcase pressure, unlike any 4T. It's not supercharging, but it is something that 4T engines do not have.
Yep I hear you mate, I just don't think "forcing" is correct terminology though. As per Matt's awesome drawings, its an open system. You "force" air into a closed container (like a forced induction 4T). In a 2T the transfer port has opened and closed all while the exhaust is opened, so there is no real container to 'force' the mixture into. By strict terminology, the exhaust back pressure is doing more 'forcing' than the positive crankcase pressure is when the transfer port opens. Just my 2 cents, I love thinking about it out loud!!
KillerWattsRacing True, but without the crankcase pressure getting the fuel and air in the combustion chamber in the first place, there would be no exhaust backpressure or pressure wave. Think about when starting the engine, it is forcing the air through. Still not supercharging!
That's it, the mixture is being forced out of the crankcase, everything else is just consequential. Matt should completely redesign a 2T and have the crankcase 'suck' the exhaust out of the cylinder and use the ensuing vacuum in the cylinder to fill it with mixture. It could be called the 'Simpsons' motor, which both sucks and blows!!
2 mocht words on a super scharch tink normal... dont forget.. is only a pomp... it runs on mix ( gas ant air ) thats it.. good story workshop, no comment !!
Maybe Santa will bring you a Reindeer with a bag of Cash... U could just work more, Ya know that always helps those that spend more then they make....LMAO
yaaay 1st :) my transfers are aimed at the opposite direction away from the exhaust to cause a swirling mixing motion but yeah it will still always piss some out the exhaust (yammy dt 125)
I think you said something that could be slightly misleading, the amount of fresh charge the cylinder receives is bound to the piston compressing the charge in the crank case on the down stroke, which isn't necessarily 100% of the swept volume of the cylinder but for expediency lets call it 100cc. If 20% of this incoming fresh charge escapes out of the exhaust then the cylinder will be 80cc fresh charge + 20cc exhaust gas. When the pressure wave pushes some back in the best case scenario would be the 20cc lost charge being returned, if that where the case you can see we would have the 80cc fresh charge + 20cc exhaust gas and now the returned 20cc fresh charge. Which clearly equals 120% of the original charge but only 80% of it is fresh charge. You can't get more than 100% of the fresh charge the crank case provides no matter how much the pressure wave returns to the cylinder. More likely the returning gas is at best 50/50 fresh charge and exhaust gas so you would end up with 80cc fresh charge + 20cc exhaust gas + 10cc returned fresh charge + 10cc returned exhaust gas. Which would be 90cc fresh charge and 30cc exhaust gas. A proper super charger would provide more fresh charge to the whole system regardless of how much escapes out the exhaust or not.
"the amount of fresh charge the cylinder receives is bound to the piston compressing the charge in the crank case on the down stroke," - I did go through this with 'cross-flow'
So to use your logic a GM diesel with a blower isn't supercharged because the blower is required to make the engine run? What about engines that use a piston charger like the Ducati V-One? thekneeslider.com/ducati-v-one-twin-to-supercharged-single-conversion/
The GM diesel wouldn't work without the blower - the word 'super'charged means exactly that i.e not normal charging but super charging. Hence why turbos are called tubo superchargers. And the ducati is supercharged and its charging the cylinder above 'natral aspiration' - can't believe I have to spell this out. Let me put it another way - if you fit a roots blower to a 2 stroke dirt bike or a turbo - then what is it? A super-supercharged engine?
Only idiot's think that is supercharging, a supercharger is a blower driven off the engine as opposed to a turbocharger drive by the exiting exhaust gasses.
Actually, the pipe does have a supercharging effect. It is not really a "pressure wave", (as in psi), but a "sound wave" that bounces off the reverse cone back to the piston before it closes. May be the biggest factor of a tuned pipe, the tuned pipe is tuned by using that sound wave, (Speed through the gasses), in relation to piston speed. The shorter the pipe, the faster the piston speed it matches, and visa-versa. According to the old 2-stroke writes of the 70's (some of the last written for publication), the pipe could charge the cylinder up to 125% of it's actual volume. That is a supercharging effect.
Regarding the supercharging discussion on 2-strokes. I have a really weird 2 stroke engine on my moped which challenges your definition of supercharging. Please have a look at the "motobecane 99z engine". Google those exact words and you will find a engine cut-out. What would you call this? Hoping you like weird engine designs :-) Have fun!
Well. As you can see it has 2 pistons. One normal 2 stroke piston and a second piston which is only used to suck more air in the crankcase and push more air towards the combustion chamber. It is an added air pump which balances the engine and passes the 50cc law. They could have placed this air pushing piston system out side the engine. It would be stupid, but it could be done. Than you would have a compressor outside the engine pushing air in making it supercharged. This outside compressor sucks outside air in. The inside version also sucks outside air in making it similar in every single way as the outside version. Okay, not exactly the same but you get the idea. Confusing isn't it?
That '120%' fill is just based on an arbitrary definition of 'STP'. If all those fuckers who call that 'supercharging' go to higher altitudes and all of a sudden the air density decreases, are they going to say their bike is 'negatively charged'? For any form of supercharging, you need some auxiliary power input into your system acting as a power source for the prime mover (usually either by leeching off a shaft or using pressure differentials to spool up a turbo turbine). Air rams aren't fucking FI Great video tho. As a 4T fucker, this is interesting as shit, keep it up
Once again, Matt is stuck in the past. The modern two stroke doesn't use anything Matt just described and hasn't for years. Matt is your Google blocked over there?
"The modern two stroke doesn't use anything Matt just described and hasn't for years." - whaty like ports? Reeds? Fuel? Cylinders? LOL you're making yourself more of a target here Dan
Matt, WHY ARE YOU TELLING US ABOUT 1960'S TWO STROKE TECH? Jaysus Fuck, nothing uses that technology including handheld two stroke power equipment. "Strato-Charged" look it up genius.
no, I genuinely like your videos, but you got the pom thing going which is genuinely irritating...we Australians have a disparaging thing we say "whinging poms" which is actually based on fact it seems. quick search on Google gives definition for whinging - "complain persistently and in a peevish or irritating way.". I'm sorry man, I don't want to troll or publicly ridicule... just want to enjoy your teaching videos... so stop whinging..!! point out the wrong shit, don't make it personal and don't go on about it... 😉
This turned into a rant in a hurry lol love the 2 stroke vids
When I re-discovered this channel after watching colin furze a couple days ago deadass thought you were him and had just found his old channel! Lol you guys could be brothers
as an 80;s 2t fan i didn't really understand how critical the actual exhaust design was to the way a2t ran,after watching this vid i now know and understand what a genius the likes of Stan Stephens were.
Good old Stan
Good bit about ram air- the actual positive pressure generated by "ramming" air into an intake tract is extremely low. . .and does very little to help cylinders fill at speeds below 160mph :)
Love the rants they are top notch ,this guy is a genius I wish more people had an actual knowledge of whats going on inside the engine and not how to replace a component.Im 16 and I drive a self-destroying kx125 and loving it .Just cant beat a power ban.Besides you should sell a 2 stroke before u ever have it long enough to need rings even .
You build em so fast folk offer to buy em on the spot eh? That's what I'm talking bout....
love your stuff. its like xmas everyday
thanks for the like matt s you can tell this is my way of agreeing with you and like you not understanding how folk don't seem to understand the basics
2 strokes are simple but it takes years to understand how the damn thing works haha
Loving these 2T videos
Oh look, what's Matt doing? Bust'n chops again? Good, good.
Anyway, love the videos, especially now since I bought myself a 2 stroke (never owned one before - it's a neat toy).
They are a hoot aren't they.
When you were talking about the trapped exhaust all that came to mind were old Detroit diesels, of course it's a complete oddball in its own right but still very interesting when looking into 2 strokes.
Diesel 2 strokes our far from odd balls and are and have been threw out the years very common and popular. Almost Every train in the world have a 2 stroke Diesel powering them since steam went obsolete.
Great explanation Matt.
Right. For fucks sake, you run quite a mouth on ya, lad!!!
Thing is - you're 115% CORRECT. The pressure differential that causes the fuel in the Crankcase to be shoved up the Transfer Ports when the Bloody Piston is driven down... Is NOT fuckin' SUPERCHARGING!!! For fuks sake!
I've been building Race Engines for Decades, and STILL have that insane debate!!!
I'm enjoying your Videos mate! You TELL it like it is, and cut straight through the bullshit!
hi
I have been watching your vids for a little more than a month now
it's good to see some real no bull educational stuff keep up the good work
NB minarelli 50cc race bike from 1960s was it good or shite
good - and thanks for the comment
to remove trapped exhaust, go to uni flow of a opposed piston 2T
Opposed piston 2 strokes are great for efficiency and have a lot of power potential. Uniflow is the most positive form of cylinder scavenging and OP is a good way to do it. Here's an opposed piston multifuel 2 stroke with a blower and a turbo... ua-cam.com/video/UxON-HIlz5E/v-deo.html
Loving the videos, especially the two strokes, keep it up great work bud.
Matt Matt Matt ,, what have I already told you?
You'd have more luck with that wall.
It's like you're talking to yourself ,, oh hang on ,, you actually are ,, hahaha
Thank you for this, excellent, presentation. This tunes my brain, some.💯
Not quite 2 stroke related, but might be one for the list because it's all about pressure waves , that fancy Opel Comprex System they used on their Diesels back in the 80s.
Nice warning love the videos keep it up 💪🏼♥️🔥
Its called savaging! NOT SUPERCHARGING! Great video bro....Dont let they zombie's get to you!
surely a supercharger works at all RPM and ram air only becomes effective when the engine/bike reaches and goes above a certain speed creating the a similar effect to forced induction
Brilliant video thank you 👁️❤️👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍
I live in Idaho U.S and these FOCKIN PLANES! every day over my house like if we dont keep flying these fighter jets overhead maybe the Native Americans might come back or something,(sarcasm) and then I get a ticket for having loud exhaust on the car I pay taxes on!
Great video keep it up.
In a typical engine say 70's 400's do you prefer a vary steep boost port or shallow such as 50 degrees?
Well explained good job
Thanks...........and Well done
OK, here's the thing. The crank case isn't really pressurised. Not much anyway. Most "modern" two strokes have about 3 times the volume in the crank case as in the cylinder (a 125cc engine would have about 350-380cc crank case volume). So when the piston is at BDC vs TDC, the mixture in the crank case has hardly compressed at all (it's only about 1:3) compared with the combustion chamber (10:1) which goes from about 125cc down to 10-15cc so there's really stuff all compression in the crankcase. When the transfer port first opens, the pressure in the cylinder is higher than in the transfer duct so it actually blows a little into the transfer. Then the momentum of the exhaust gasses rushing out the exhaust port starts to pull the air/fuel mix into the cylinder. The pressure at this point in the transfer duct is lower than 1 bar so it must be sucking the mixture, not blowing it. This especially true when the engine is on the pipe (in the powerband) where the expansion chamber is working its best. That's one of the reasons a two stroke will run like crap without a decent pipe. It's not just the pressure wave forcing the mix back into the cylinder before the exhaust port closes. But as you say, it's bloody complex and it's certainly not supercharged.
"pull the air/fuel mix into the cylinder." - lol pull
"the pressure in the cylinder is higher than in the transfer" - exhaust port opens first
"The pressure at this point in the transfer duct is lower than 1 bar so it must be sucking the mixture, not blowing it" - don't get this bit
"It's not just the pressure wave forcing the mix back into the cylinder before the exhaust port closes." - so what is it?
Matt, I've taken a closer look at the data I have and I have to admit, I'm wrong on a couple of things. I'm looking at data for a Honda RS125 GP engine so everything below is in reference to that.
As you said, the air/fuel mix is in fact mostly forced into the cylinder by crankcase pressure. There is a part of that process where the pressure at the transfer port is less than 1 bar but that's just as the transfer port is closing. Most of the flow into the cylinder is under positive pressure as you said. But, when the transfer port first opens, the pressure in the cylinder is still higher than the crankcase and there's a moment where some exhaust gasses are forced into the transfer port. Then as the pressure inside the cylinder rapidly reduces, the crankcase pressure pushes those exhaust gasses back into the cylinder along with the air/fuel mix. In an RS125 engine, the crankcase pressure never goes above about 1.5 bar so my point remains on how low that pressure is compared with whats going on in the cylinder. So until the cylinder pressure gets below 1.5 bar, the air/fuel mixture cannot enter the cylinder.
Anyway, the point I'm making is that I didn't get all my facts straight before. Sorry about that.
Chris you where right first time, the depression caused by the expansion chamber 'pulls' the mixture thru the transfers. Your note on the higher pressure in the cylinder on transfer port opening causing reverse flow in the transfer passages is also correct.
Where is part 2?
what happens if you change transfer port angle for fuel mixture to go directly up towards spark plug? is their any benifit?
A slight one yes.
This info is so good.
Who is pissing you off? MAAAD Matt, the thunder dome!
LMAO!
It would make also a good title for an rant video ;)
mad matt xD
So first it was your mate sticking his foot in the lift door and now it's toothpaste!👍🏻👏 How about a small opening just below the squish in the head and a chamber for the trapped exhaust to be pushed into?
but then what happens to it?
chris davidson When the exhaust port is cleared it empties out the cylinder head into the exhaust.Anything to give a nice fresh mixture around the spark plug? I'm sure there would be a problem with it,detonation,carbon?
hmmm... i was thinking that it'd get stuck in the chamber, as if the exhaust gas gets trapped against the head, how's it going to get back out of the chamber?
This is the problem when trying to explain the dynamics of a tuned pipe equipped 2 stroke. The reverse pulse wave from the pipe packs in more pressure just as the piston is closing the port. No-one should say that it's supercharged. But rather to the lay person, it is a "supercharge effect" as in pressurizing the chamber. But ONLY at the sweet spot of RPM when the reverse pulse reaches the closing exhaust port at just the right time. We are not preaching to the choir, we are trying to explain to the guys that have never been to church. A static adjustable length header section on the pipe, can change the distance from the convergent cone to the exhaust window, and that will change the timing of that reverse pulse. That adjusts the point of the sweet spot, or the supercharge EFFECT, or hitting the pipe. That is how you can TUNE your tuned pipe.
I agree , not supercharged. But , could we call it pulse charged ? Just asking.
Is part 2 out? What's the title?
Yamm had angled transfer ports to go out it a y shape and the boost port helps sandwich exhaust gases out. Sorry for short analogy but that's it in short.
Not totally and that in part 2 stop jumping the gun
the thumbnail shows it but i kinda missed hearing that todays 2T use the schnuerle porting and how the flow looks there ;-)
but it says part one so this'll be said im sure
That's in the next video hence the part 1 in the title
The Workshop sweet
Are there variable exhausts that can adapt somewhat to the motor?
yes they have valves ypvs
Leandro5999 Is right, thats what power valves basically are
I wonder if the orignal designers of 2 strokes knew that fuel could come back in the combustion chamber, or was that figured out later on in developement? The 2 strokes I grew up riding ('73 Yamaha GT80,MX100) didn't have expansion chambers. At least I don't think they did. The large expansion chamber with a very narrow stinger seems to have come about in the mid 70's.
Supercharging is defined as a volume of gas trapped in a cylinder that is greater than that if the trapped volume was freely allowed to occupy the cylinder at the same temp and atmo pressure, no matter how that greater trapped volume was achieved
So inertial filling of a cylinder using valve timing is supercharging? If so then pretty much every bike engine is supercharged.....
Yep! anytime cylinder filling goes over 100% DR, that supercharging.
LOL don't be an idiot. So the R1, GSXR and the CBR1000RR are all supercharged - LMAO
Oh ok mate, you know best !!!
There are and has only been 3 production 'supercharged' bikes - fitted with superchargers
- Kawasaki H2 and H2R
- Peugeot Jetforce Compressor
- Vyrus 987 C3
- BMW Type 255 (was a race bike - not production)
Seen as though Kawasaki made the statement that this is the only supercharged production bike availible then you need to tell kawasaki they are wrong.
atmospheric pressure versus forced induction, case over. you would have to be going about mach 2 for ram air to be called forced induction.
Impossible to supercharge a conventional two-stroke engine with symmetrical port timing. Supercharge in any two-stroke requires the exhaust port to close well before the transfers do.
Wrong. Snowmobiles are turbo'ed all the time
How do you supercharge when all the incoming charge blows through the cylinder during the scavenging process and straight into the exhaust pipe? You need to charge a closed cylinder under positive pressure to achieve any increase in mass charge. The charge pressure in a two-stroke is equal to the exhaust back pressure because the exhaust remains open after the transfers close.
"How do you supercharge when all the incoming charge blows through the cylinder during the scavenging process and straight into the exhaust pipe?"
- the 'force' of the returning pressure wave is proportional to the combustion in the cylinder. You have a supercharged engine so the pressure wave has a higher energy. Granted you have to match the exhaust to the system but it can be done.
I did a video called 'can you turbocharge a 2 stroke. This isn't supercharging but the principle is the same.
You said yourself that the reverse pressure wave was not true supercharging! You would need to have further charge mass entering the cylinder as the reverse wave is having its effect and this would occur at only a very narrow range of rpm as it relies purely on resonance.
Turbocharging and supercharging are different animals... Turbo creates back pressure proportional to the charge pressure so it works even if the exhaust port closes after the transfer port... with supercharging you can't raise the volume / pressure in the cylinder because the exhaust is still open to the atmosphere after the transfer port closes.
dude secretly loves the 2t engine, but absolutely hates stupid people who piss him off by not knowing how 2t actually works
They use systems in cars to recover exhaust gases and useing them in the next cycle, so they can lower the emissions.I think its to lower the burning temperature and so reducing NO emissions(in diesel engines also the unburned carbon particles). For me it makes sense to build such a system for diesel engines but does it also makes sense for gasolin engines. Just asking because of those 15% exhaust gas in the chamber.
CAT has a thing called ACERT that does EGR internally with valves.... By nature most 2 strokes have some exhaust gas in the mix at the time of combustion. Exhaust gases lower the peak combustion temperature reducing the formation of NOX.
How far does the air fuel mix go out the exhaust ? Is it with in a foot
rpm variable - but a good question
The Workshop I have another idea for 2 strokes make like a compression chamber out side of the motor by taking exhaust pressure and using that or something of that sort I'm not saying that it would work but it might
Some will go all the way do to dilution between the 2 gasses and that is the reason 2str are band by many places!
waiting for Dan's comment
Sloan V Lol! why?
Steven Donald I get a kick out of it
Sloan V cuz Dan is a tosser!
@@bacilluscereus1299 not that I remember
could you do a video on why a hotter exhaust pipe increase performance?
Yes I can
Infact I have - search 'exhaust wrap' on my channel
I agree it is not supercharged, however, if the crankcase was not pressurizing the crankcase, the engine in your example wouldn't run very well, maybe not at all. Also, a 4 stroke doesn't use the crankcase pressure to force air and fuel into the intake, so a simple 2 stroke is obviously getting something more than a 4 stroke is. Yes, most* 2 stroke's natural design is to use this crankcase pressure, but that still doesn't negate that it is forced induction of some sort, to some degree. Still, I agree, NOT supercharged.
If you take away a supercharger from an engine, it's still an engine and it still runs. You take away crankcase pressure variations from a 2T, it's no longer an engine because it doesn't run. It's not supercharging, it's called inherent 2T design function.
KillerWattsRacing Right there with you, totally agree. I do think you will also agree that 2T design function INCLUDES forcing air into the combustion chamber from crankcase pressure, unlike any 4T. It's not supercharging, but it is something that 4T engines do not have.
Yep I hear you mate, I just don't think "forcing" is correct terminology though. As per Matt's awesome drawings, its an open system. You "force" air into a closed container (like a forced induction 4T). In a 2T the transfer port has opened and closed all while the exhaust is opened, so there is no real container to 'force' the mixture into. By strict terminology, the exhaust back pressure is doing more 'forcing' than the positive crankcase pressure is when the transfer port opens. Just my 2 cents, I love thinking about it out loud!!
KillerWattsRacing True, but without the crankcase pressure getting the fuel and air in the combustion chamber in the first place, there would be no exhaust backpressure or pressure wave. Think about when starting the engine, it is forcing the air through. Still not supercharging!
That's it, the mixture is being forced out of the crankcase, everything else is just consequential. Matt should completely redesign a 2T and have the crankcase 'suck' the exhaust out of the cylinder and use the ensuing vacuum in the cylinder to fill it with mixture. It could be called the 'Simpsons' motor, which both sucks and blows!!
2 mocht words on a super scharch
tink normal... dont forget.. is only a pomp... it runs on mix ( gas ant air ) thats it..
good story workshop, no comment !!
Maybe Santa will bring you a Reindeer with a bag of Cash...
U could just work more, Ya know that always helps those that spend more then they make....LMAO
Why did your guy Martin video get blocked?
Because it has a tt racing clip in it and they have banned the video from everyone
If you put a blower on a 2 stroke you call it super-duper charged.
yaaay 1st :) my transfers are aimed at the opposite direction away from the exhaust to cause a swirling mixing motion but yeah it will still always piss some out the exhaust (yammy dt 125)
Sorry but you need to look at a drawing again of your engine Yamaha where very good with 2T.
me? ive got a cylinder right in front of me right now no need for a drawing i can see the transfers..
You are correct you want to direct transfers to the upper intake side of cylinder to promote exhaust savaging and good fuel charging...
What if you made a trombone like exhaust, then you can supercharge it in a bigger rev-range.
😉
I'm confused.. You got people calling 2 strokes peak exhaust scavenging - supercharging?
I think you said something that could be slightly misleading, the amount of fresh charge the cylinder receives is bound to the piston compressing the charge in the crank case on the down stroke, which isn't necessarily 100% of the swept volume of the cylinder but for expediency lets call it 100cc. If 20% of this incoming fresh charge escapes out of the exhaust then the cylinder will be 80cc fresh charge + 20cc exhaust gas. When the pressure wave pushes some back in the best case scenario would be the 20cc lost charge being returned, if that where the case you can see we would have the 80cc fresh charge + 20cc exhaust gas and now the returned 20cc fresh charge. Which clearly equals 120% of the original charge but only 80% of it is fresh charge. You can't get more than 100% of the fresh charge the crank case provides no matter how much the pressure wave returns to the cylinder. More likely the returning gas is at best 50/50 fresh charge and exhaust gas so you would end up with 80cc fresh charge + 20cc exhaust gas + 10cc returned fresh charge + 10cc returned exhaust gas. Which would be 90cc fresh charge and 30cc exhaust gas. A proper super charger would provide more fresh charge to the whole system regardless of how much escapes out the exhaust or not.
"the amount of fresh charge the cylinder receives is bound to the piston compressing the charge in the crank case on the down stroke,"
- I did go through this with 'cross-flow'
No it wouldn't.
7:13 Schnurle loop.
Dunna look at me mate
is there actually people that consider crank transfer forced induction?? wow that almost tops dumbest thing I've heard.
So to use your logic a GM diesel with a blower isn't supercharged because the blower is required to make the engine run? What about engines that use a piston charger like the Ducati V-One? thekneeslider.com/ducati-v-one-twin-to-supercharged-single-conversion/
The GM diesel wouldn't work without the blower - the word 'super'charged means exactly that i.e not normal charging but super charging. Hence why turbos are called tubo superchargers. And the ducati is supercharged and its charging the cylinder above 'natral aspiration' - can't believe I have to spell this out.
Let me put it another way - if you fit a roots blower to a 2 stroke dirt bike or a turbo - then what is it? A super-supercharged engine?
lol probably should have used different color or the exhaust gasses and new charge
good Good explanation ;) .Can you help me sir?
It depends - what do you need?
frankly i have a suzuki rm85 But without a cylinder and I think about its manufacture, is that possible? TNX for a response
Do you mean you want to make a cylinder?
yes *I have the idea But I have no information on the type of aluminum and its components . His first success rate 25/°
Well are you casting or machining from billet?
Only idiot's think that is supercharging, a supercharger is a blower driven off the engine as opposed to a turbocharger drive by the exiting exhaust gasses.
yes but remember that a turbo is a turbo-supercharger
Does Matt get royalties every time he mentions Yamaha R1/R6? That or he has wet dreams about them :)
I wish, the wet dream and the money
lol its supercharging lol motomam says so
Actually, the pipe does have a supercharging effect. It is not really a "pressure wave", (as in psi), but a "sound wave" that bounces off the reverse cone back to the piston before it closes. May be the biggest factor of a tuned pipe, the tuned pipe is tuned by using that sound wave, (Speed through the gasses), in relation to piston speed. The shorter the pipe, the faster the piston speed it matches, and visa-versa. According to the old 2-stroke writes of the 70's (some of the last written for publication), the pipe could charge the cylinder up to 125% of it's actual volume. That is a supercharging effect.
Regarding the supercharging discussion on 2-strokes. I have a really weird 2 stroke engine on my moped which challenges your definition of supercharging. Please have a look at the "motobecane 99z engine". Google those exact words and you will find a engine cut-out. What would you call this?
Hoping you like weird engine designs :-) Have fun!
That's a piston ported 2 stroke. How does this challenge supercharging? They're very simple and old. Great fun to fuck about with though
Well. As you can see it has 2 pistons. One normal 2 stroke piston and a second piston which is only used to suck more air in the crankcase and push more air towards the combustion chamber. It is an added air pump which balances the engine and passes the 50cc law. They could have placed this air pushing piston system out side the engine. It would be stupid, but it could be done. Than you would have a compressor outside the engine pushing air in making it supercharged. This outside compressor sucks outside air in. The inside version also sucks outside air in making it similar in every single way as the outside version. Okay, not exactly the same but you get the idea. Confusing isn't it?
That '120%' fill is just based on an arbitrary definition of 'STP'. If all those fuckers who call that 'supercharging' go to higher altitudes and all of a sudden the air density decreases, are they going to say their bike is 'negatively charged'?
For any form of supercharging, you need some auxiliary power input into your system acting as a power source for the prime mover (usually either by leeching off a shaft or using pressure differentials to spool up a turbo turbine).
Air rams aren't fucking FI
Great video tho. As a 4T fucker, this is interesting as shit, keep it up
555
👍
Just wasted 30 minutes looking for part 2
Once again, Matt is stuck in the past.
The modern two stroke doesn't use anything Matt just described and hasn't for years.
Matt is your Google blocked over there?
"The modern two stroke doesn't use anything Matt just described and hasn't for years."
- whaty like ports? Reeds? Fuel? Cylinders? LOL you're making yourself more of a target here Dan
Cylinde :)
wat about a 2 stroke diesel? the supercharger is necessary for it to run, u cant take it off and run the engine without it, but it IS supercharged
that's a 2 stroke diesel the clue is in the name
Matt, WHY ARE YOU TELLING US ABOUT 1960'S TWO STROKE TECH?
Jaysus Fuck, nothing uses that technology including handheld two stroke power equipment.
"Strato-Charged" look it up genius.
You mean stratified scavenging dumbarse LOL - if you're going to make a point know what its called first
Didn't get 25 seconds in...you have absolutely no idea
Where is part two?
Matt get your money back from engineering school. You were ripped off.
good video... could be better if you didn't whinge so much
Aren't you whinging now?
no, I genuinely like your videos, but you got the pom thing going which is genuinely irritating...we Australians have a disparaging thing we say "whinging poms" which is actually based on fact it seems. quick search on Google gives definition for whinging - "complain persistently and in a peevish or irritating way.". I'm sorry man, I don't want to troll or publicly ridicule... just want to enjoy your teaching videos... so stop whinging..!! point out the wrong shit, don't make it personal and don't go on about it... 😉
sorry, my bad, I take it all back, you keep going you good thing..!! 👍
Where is part two?