How to Make the Most Powerfull Two Stroke - P1 Porting
Автокөліктер мен көлік құралдары
While waiting for parts necessary to continue with the new engine..
Lots of comments asking why I think it will be the most powerful ever, it's time to explain the theory in detail, I'll try to lay it out as a how-to.
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First the exhaust port and duct.
It's simple compared to the transfers, The goal is to maximize port area and flow through the duct.
There's a few constraints you have to work within for an exhaust port to work.
- Width of a single port can't be too wide without snagging the piston ring, max is proportional to bore diameter, port shape(flat top less forgiving vs radiused, radiused corners.),and ring properties.
An old rule of thumb is around 70%, but you can go wider on smaller bores/not so wide on larger. To circumvent this there's twin, tripple, and even quadruple ports. Going past 100% of bore width has proven to loose power because it disturbes the scavenging, the dance between transfers and exhaust.
- Height, can't be too high otherwise you'll screw up resonance in the pipe.
I'll talk more in detail about this when we get to that pipe. In short, when the port opens a pressure wave starts traveling down the pipe, gets reflected by the convergent cone, and starts traveling back towards the port. We want this to return as the piston is about to close the port to effectively close it earlier and push fresh charge sitting in the duct back in. We also want a portion of this wave to hit when the port is closed and be reflected back. This reminder of the first wave will join forces with the next wave as the port opens again and strengthen it slightly. This then repeats for the next cycle, and the next, and so on and so forth. Resonance.
About 190deg port duration is optimum for resonance, part because the real wave doesn't start traveling until a few degrees after the port is initially opened, part because you want the wave to be a little late on the return for parts of it to be reflected back.
You should make the port high than 190deg tho, I'll get to why soon.
Don't make the port too close to transfers, will cause short circuiting,fresh charge going straight out the exhaust.
My cylinders exhaust port
- First thing you'll notice is that it's definitely breaking the single port rule of thumb for safe width, it's at 100% bore width. Why no bridges is simple, bridges reduce effective area and cause turbulence and skin friction. I'm running a special retained ring/custom piston combo, we'll get to that in another episode. The sole reason for this width is to maximize blowdown area, the area of the port above the transfer roof height, the part that's open before the transfers are uncovered.
This is what's important, the rest of the port is not, in fact in my design I've raised the exhaust port floor to almost transfer roof height. This serves a dual purpose, keeps velocity high in the duct, and reduces short circuiting from the A transfers.
Port duration is 198deg, there's a relatively large bevel on the almost flat top edge bringing it up to about 204deg effectively.
The flat top to maximize area, the bevel to increase flow, and make life easier for the ring. The reason for exhaust duration above what's best for resonance is to gain more time area,to allow the engine to rev higher - as long as the loss in torque is less than what you gain by rpm you'll increase power.
The duct.
The duct is shaped to maximize flow and keep velocity high. Three important features.
- Bulges. Spent gases don't just intuitively want to exit the cylinder at the direction of the pipe, they want to get out as fast as possible, radially straight out. The bulges are there to gently persuade them in the right direction, a "straight out" port might make them upset, have them spend more energy on their exit.
- The duct exit is smaller than the effective area of the port, about 75%, This to keep duct velocity high, about mach0.8 at the exit.
- Very high exhaust floor, promoting blowdown flow, low volume keeping velocity high.
Between the pipe and duct exit there's a short transition piece.
This quickly brings the smaller duct exit out to the header diameter which is 100% of effective port area.
This steep transition because in the pipe we want high pressure/low velocity vs. in the duct where we want high velocity/low pressure.
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Пікірлер: 543
Videos like this really complement the normal build stuff. Understanding the ideas behind your design decisions makes everything more interesting, and you're good at explaining them. Keep up the amazing work!
@2STROKESTUFFING
3 жыл бұрын
Thanks man!
@henkm9905
3 жыл бұрын
I agree, it makes us better understand what the deal is.
@jimwolfe2862
3 жыл бұрын
Couldn't agree more. Keep up the good videos in both formats.
@DR-br5gb
3 жыл бұрын
I second this!
@paddy2661
3 жыл бұрын
Spot on totally agree. Little bits through the build and you wonder how important it is.
This is good "filler" content, while the main content needs time to come out, this is just as interesting in my opinion. Looking forward for more!
@kiiiisu
3 жыл бұрын
for sure, makes undestard whole thing :D
@macelius
3 жыл бұрын
Patience, this is a culmination of years of work and experimentation.
@darealkosmo
3 жыл бұрын
filler? this is golden knowledge.
@128p6
3 жыл бұрын
@@darealkosmo Thats why i put " " around filler :)
@snafuequals
3 жыл бұрын
I like this content just as much as the rest. Right up my alley.
You are the most knowledgeable two-stroke man I have ever listened to
@2STROKESTUFFING
3 жыл бұрын
Just because I've listened to lots of knowledgeable two stroke guys!
@DarkSifu
3 жыл бұрын
Not to toot my own horn, but.. Braaaap braaaaaap braaaap wiinng wiing. Im pretty intelligent myself. 😏 lol
@ikes7182
3 жыл бұрын
@@2STROKESTUFFING awesome vid my guy super interesting, good luck with your project
@spacebrowni6761
3 жыл бұрын
@@DarkSifu wanna put that to the test?
@raphrath8561
3 жыл бұрын
@@spacebrowni6761 it would be a waste of time, hes at the four a level there's n way to measure it
I can just imagine the faces on the kids at your kindergarten while you stand at the white board explaining the fundamentals of two stroke tuning. Awesome explanation, thanks.
You are the gale banks of 2-strokes, thank you for sharing your hard earned knowledge. Been watching your channel for years.
I love this kind of explanation/education - and you do it really well... i guess you are used to explain stuff to all the kindergarden kids at work 😊
@k-h469
3 жыл бұрын
Probably teaching the kids about two strokes everyday :D
@msgofast
3 жыл бұрын
@@k-h469 🤣🤣🤣👌
@williambrodmanvi5944
3 жыл бұрын
Proof ya wanna know something teach it!
Theory lessons is nice. Thanx!
Thanks for taking the time to explain to all of us cheering you on what exactly it is we are watching.
its fun to tinker on these small cc 2 strokes cos when u do something ringht it will be a noticable difference compared to a big 125 or 250 cc cos they run very good anyways. I have a honda automatic PXR 50 cc with a Polini 70cc sylinder and have made my own exhaust to make it run better. then I took a proma from honda mb5 and changed it to fit and it made a better powerband. reed inlet area was tiny tho so I removed it and put a honda mt5 21 carb and big reed to fit with this homemade adapter inlet plate wich allowed the entire hole in the crankcase that was meant to host the original reeds to be used and now it runs way better cos it can flow more fuel and air. A buddy has this roller bench in the ground to measure horse and torque on cars but he also masured his moped. i need to get mine measured cos im sure it should be 10horses in this one now ;)
There is no confusion. Nice explanation of your work. You are right on, about everything you explained. I wasted over 1000 gallons of water checking the flow porting, Bultaco's, CZ's and Yamaha's back in the mid 1970s (Also a garage full of pistons and sleeves).
I really appreciate this. I started this series pretty late and didn't get any of the background.
@JbFixCorleone
3 жыл бұрын
So y not watch older episodes? It’s All up here..
keep going man
I'm the one that really doesn't like listening nor reading theories (because of the issues remembering most of things said/read, i'm that practical kind of dude), but this one is the one i am into and that made me want more of it. Looking forward for the main project and also the filler content in between while there's a waiting process in background! ;) Great job!
Have actually learnt a lot about 2 strokes, nothing wrong with the way you explain things. Keep them coming !!!
Great stuff, it’s refreshing my memory from 2-stroke tuning in the 90’s.
Thanks! I wish I would have known 10% of that when I tuned my moped 40 years ago.
This kind of videos are the sole reason started watching you. Keep up the good work.
I could sit and watch and listen to you for hours I've learnt so much from you mate keep it up and I've no doubt it will be the most powerful two stroke 👍
this video is a clear indicator of just how much work has gone into making this engine,i'm bloody amazed at how much knowledge has been learned,and even moreso that it can be presented in a digestable form.keep up the inspiring work!!!!
Great refresher, I've been watching since the beginning but it was good to bring it all together and keep the reasoning freash. Keep up to great content 👍
It cannot be overstated how good the editing is on this. This on other channels could have been a 90 minute video, but you did it in such a way that it was engaging, insightful and straight to the point. One of your best videos yet!
Brilliant explanation. Always had expansion chambers on my 2 strokes, had a rough idea how they worked but this way very detailed.
Genius! This is real tuning .For two stroke it's precise prediction .Keep on moving to the peak of success. Am fond of 2strokes. . . !Am still learning. .
Amazing. Clearly you’re very knowledgeable of all things two stroke and as a fellow builder I am blown away by your dedication to design your own engine and then document the process for people like myself on KZread! I’ve been watching since the beginning of the project, keep up the great work!
i know a lot about 2 stroke, but when i listen to your advice i know now i know nothing really. thank you for the education
I don’t know as much about 2 strokes as you, but I always look for your videos because I always learn something. Thank you for sharing your knowledge.
A comprehensive explanation of high performance 2 cycle Cylinder, Piston, Ring, Port, Pipe, Head design facts, theoies and best application practices.
yes, most of us (viewers) are not 24/7 nosedeep into 2strokes, so this explanation really shines a light on the details. interesting stuff!
I know more about 2 cycles than the average person, I have worked on them, modified them for years, but your depth of understanding and methods of explaining is mind blowing. I have read lots of old literature from the 1960s and 1970s explaining some of this stuff, but I find it really had to retain information like this. The basic principals stick with me, but when I'm trying to put any of it to actually building something, I do a LOT of rechecking, reading and google searching to see if what I remember is correct. Anyway, Cheers ! Great video ! More of this please !
Just started watching your channel. I love 2 strokes and this is so interesting. I like this format as it helps aid understanding
I love the knowledge you bring to the table man is very nice to hear in-depth how things work I love to learn and it's nice that somebody explains it like you do
This was the perfect level of detail for me. I understand the concept of how a 2-stroke works but not the details, and this video made me understand the 'why' of your design. Thanks for taking the time to explain :)
Great video! I really love your channel! Not only are you bringing us down this journey with you but your taking the time to explain your theory...
WOW my 2STROKE IQ just went up after STUFFING your teaching in my brain, great job. I feel more equipped to understand the re-engineering of your engine design. Keep up the great work, you are really blessed with a gift to be at the level of knowledge you have and able to teach your subscribers. Thank you from NC, USA Phil 4:13
This sort of video really helps to explain the theory behind what you’re doing.. love it. Please make more like this.
One of my favourite videos so far because I LOVE the nerdy side of engine building and I focus on 4stroke so I know nothing about this which makes it much more fun
Every time I watch your videos I learn something new. Keep up the good work!
Very clear, concise and over all well put together. Matt over at The Workshop better watch out!
It was great to learn about the thinking behind what you have done. Keep it up!
Brilliant! You are actually very good at explaining complex technical stuff in a very easily understandable way - including the analogies. That's a gift you can treasure. I look forward to more explanations like this and previous ones, like electroplating and your dynamometer.
Great job Love the new concept! keep them coming ... the majority of people only see the end result and are not interested in how it is made and how it is achieved.
Really great to understand the technical reasons of what you have learnt! More please, great channel
i cant say for everyone but for me these informative episodes keep me locked in glued to the tube. even if i cant understand all of it. Witch isn't a cheap shot at his English accent, I think that actually helps. but rather a admittance to my ignorance to all the inner workings of a 2 stroke engine. kinda sad to admit brings how many tens of thousands of hours i have had one burning petrol and oil right between my own legs in my lifetime. Don't get me wrong tho i do also enjoy the ones with no talking just a good craftsman hard at work sharing his knowledge that is way easier learned by just showing rather then telling. great channel, super top notch editing the works hard to believe done by just one man not a team of. doing in his spare time, after a day of regular work impressive.
Awesome videos dude. I learn something new everytime I am on your channel. And your craftsmenship is admirable. Good luck with the rest of the build 👀👌
So I’ve been telling my husband for the last few years. After watching him work on his bike over and over again. And reading a lot of stuff what goes in must come out. care about his two strokes. I’m just saying, I enjoy the fact that you were confirming everything that I have said.
Listening to you is like reading Graham Bell! Nice job. Now i have motivation to finish my 60cc power plant
thats very good intel there mate..2 stroke performance is a mysterious beast to master..thanks for these easy explanations.
This is excellent mate. Very pleased you are happy to share this information. Keep it up.
Excellent !. I know a bit about 4 stroke car engines but nothing about 2 strokes, but I am.i tested as a friend has some scooters. You explain the black art of this very well , thankyou!
excellent video i didnt understand half of it but its nice that you are demonstrating your choices and why you made them the way you did. keep up the work its awesome to see you are in a good flow and producing a lot of video's keep up the good work
Thank you a great teaching video full of answers to difficult questions.
Very interesting to learn the thought process behind all of this. Thanks for sharing.. 👍💪
Thanks! This was good info. Please continue with other topics, transfers, case, pipe etc
It's great stuff keep up the good work really like your videos I was doing this kind of stuff in the early 70s to make Mach 3s fly. Technology has changed tremendously. Good luck with the build
No, no.. that was a real help. I have not spent much time playing with two stroke engines.. (I was always a car guy with plenty of 4 stroke experience) That really helped me to understand what is going on inside of a 2 stroke.. and like the little Oliver in Oliver Twist I ask "please sir, can I have some more?" I maybe old but I do enjoy learning new things.. Soon (when I understand a bit more) I will be going out and play with an old 2 stroke engine from a gas weed trimmer I have in the garage.. I haven't played with it because I do not fully understand how it works.. So thanks my friend.. be safe, have fun and please.. carry on!
Very good explanation. Thank you. I am learning a lot from this. Please keep explaining what and why.
Im so exited to hear the sound of this little beast when its ready
Super nice to see this on the board.
i don’t know much about 2 strokes but this video seemed to help me visualize some of the things discussed and i guess kinda the reasoning behind it
This video was super helpful and really loaded with knowledge!
Wow, your mind is incredible. I have only recently found a love for 2 strokes after inheriting a mobylette from a family member. Love your channel. Can't wait for the next video.
@2STROKESTUFFING
3 жыл бұрын
😁👍 Moby's are the most beautiful mopeds in my eyes!
Exited to see your progress man. Keep it up!!
Love the format, you are a star ⭐️ Looking forwards to tx ports 😀
really great video. interesting stuff. Easy to follow and hard to deny the logic behind everything. Thanks.
Its going to be one of the most powerful 50cc single 2 strokes out there. It will also be a great way to show how tuning purely for peak power at max rpm creates an engine that is of no use except for a single niche area. (lsr) as even in drag racing you need power in the top 3rd of each gear to maximise acceleration. Its an amazing testbed/means of exploring ideas and a LOT of what you have done here will find its way into other engines. Taking the parts of the build that will benefit them in their role, the same way MotoGP and F1 you see parts of their design migrate to road cars. (VVT, small displacement turbo's, Active Aero etc) I'm loving the walk through and explanation 9f each thing you are trying!
@alancollard8939
3 жыл бұрын
it wont
@jediknight1294
3 жыл бұрын
@@alancollard8939 I suspect it will be one of the most powerful 50cc motors of its number of cylinders and displacement around in its final form. The rest of the LSR bikes are up there. Lo9king at the other powerful 49cc bikes (looking at at the crank figures to eliminate gearbox vs cvt vs direct drive) Honda RC115 was a twin cylinder and 15hp so irrelevant in comparison to this motor, The Single Cylinder RC110 was 9.5 so less powerful than the last dyno'd motor and revved to only 14.5krpm vs this 20k. Also it only gained that 9.5hp from a 9 gear gearbox which is going to be more efficient and deliver more power than the CVT. The suzuki triple was 19hp but again 3 cylinders and 14 years with the parallel twins being about 15hp The Woelfe engineering Axairo ISN'T a 49cc engine, it is a rotary and given how rotary engines work you can play fuck fuck games with the cc that is claimed. An RX7 can be registered in the UK as a 1300cc engine and the Norton rotary measurements varied between 600cc and 1800 depending how it was measured and this one is when measured properlytaking into account the rotary system and how it works is 300cc. That is 44.25 at 8750rpm but again it isn't a 50cc engine so it is irrelevant. So most powerful 49cc single cylinder two stroke is both a reasonable target and something he has a decent chance for being in the top 5 out there.
@jimmycreek
3 жыл бұрын
Once he's got it dialed we could potentially have a two cylinder model, won't be 50cc but will have the torque to blow your pants off.
@zxtimmy4
3 жыл бұрын
@@jediknight1294 I'm surprised no one has made comparisons against the 50cc water cooled minimoto engines. The IAME M-50 dyno's around 16.5hp at the rear wheel (stock), going through a centrifugal clutch. I've personally seen a SPS bottom end, with a BZM cylinder redline to over 20k rpm. Crank power estimated around 20hp.
@macelius
3 жыл бұрын
Considering exhaust port area is one of the most limiting factors, the 360 degree exhaust port with fewer bridges certainly gives it the potential to be quite literally the most powerful gasoline 2t (per cc, if that's not obvious).
Thank you for your time talking how and why.
Thank you for sharing this about the porting love video I never understood any of the reasoning of porting I just knew it was critical thank you for some enlightenment I would love more content like this
Really enjoy 2 stroke theory, studied it a lot years ago. This video is Excellent and easy to understand, even if one only knows the fundamentals of the 2 stroke engine im sure they would understand and find it very useful. Thanks and looking forward to another involving the transfer ports.
That was fantastic thank you. I know you have explained this before but not with such insight. Thanks again 👌
Love these explanation videos! Keep Them coming! Much love from a nordik neighbor (Denmark)
Still loving the channel and your work even when it’s bit over my head I trust you know what you doing and can’t wait to see the dream come true
New to 2 strokes my self very informative video thanks!!
Very interesting, keep rolling, I was going to ask about a rooster bottle, I fitted one on my 125, with fibre reeds and an expansion pipe and skimmed head, this smoothed out the power band, so much so I locked up the small end bearing in the end.
Really like this kind of format
Been here since the beginning, You´r channel is waaay underrated. Keep it up!
This was an absolutely great 2-Stroke explanation video! Bravo! 😊👍
Really like how ur production is constantly improving 👍🏻 And u made so much sense! U have taught me a lot! Love the content! From uk 🤙🏻
Damn, you drawing things out helps make sense of how it all works. I fully support more white board two stroke classroom sessions
Great stuff! Looking forward for next stuffing.
Love the content can’t wait for more of the these explanatory videos. I am learning so much from you. Thank you.👍
This video explained lots of things that I didn't know from watching the previous episodes.
Great to have you back
It is pure home made brapp 100% you and looks like a lot of fun in the near future great build series.
Awsome 👍 very well explained also very nice that you throw in a couple of numbers so i can apply this to optimizing normal 2 stroke cylinders
Yes please, transfers, the theory behinfd the resonance open intake, could listen to this for ages!!👌🏻
Great job evolving the videos man! I love it 😁
I’m wathing you from the begining and it is a good idea to sume up everything, specially degrees of exhaust and transrers. Bryliant job
Exhaust duct and the flange adapter thingy create a delaval nozzle, and when the return pulse is filling the cylinder from the exhaust you gain pressure rise greater than conventional porting can produce. This design really is above the rest. Awesome stuff man, really awesome. Resonance supercharging at its best!
I like! Learning so much faster than only reading it in books, forums etc...
Thanks man, I look forward for new videos! 😉 Great job!
FANTASTISKT ! VI VILL SE MER :D Tack som fan för otroligt intressant material ! This WILL be the most powerfull 2stroke in the world for sure :D
Yes please maintain this format. Very interesting. 👌👌
Nice explanation. Also about the standing wave of pulses to create the turbo effect. Nice to see someone busy who shows all people that the most important piece of a 2-stroke is the neglected pipe to a proper port shape. Im really anxious to see this making the full potential, I don't know how much power it will make, maybe even more than some 50cc tuners do here (27bhp!) maybe not. But a very nice series.
Awesome video! My favorite yet!
This is really awesome content I hope you will be able to film full time eventually I love every bit of engineering you put into your designs I love building my own projects because there is always room for improvement and creativity keep up the great work and stay safe man 👍
👌Entertainment and education in one format 👌 Thanks for sharing ✌️
This is great. Pls do more videos like this. It’s like having a 2stroke tuning book but on a video 👍.
Wonderfully and easily explained
VERY informative! Just for giggles, "mach" would be "trans-sonic". Worthy of note is your bulges, exit, and adaptor taper form a venturi, which promotes that transition from "low pressure high velocity to high pressure low velocity" at both inlet and outlet... well designed and thought out!
Very clearly explained! I enjoyed it.