Will This Revolutionize Two Stroke Engines?
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- เผยแพร่เมื่อ 6 ก.ย. 2024
- I have a plan!
Mark Atkinson - extremely talented!
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Thank you for the kind words. I am glad there are lots of two stroke fans left that still want to see them evolve. Neels is a very smart guy and a big part of that evolution. If you are going to do new cylinders have you thought about Frits Overmar's FOS cylinder? I am not positive but I think he has shared that as an open source project. Speaking of open source; the piston and design and make is open for anyone to use. I will download a version to grabcad. If someone can improve it that would be great... just leave any improvements open for everyone.
Absolutely. Any man with a love of mechanical gadgets loves their 2-stroke engines. it's sad to see them phased out because they make a genuinely awesome racket!!
There's a bloke out of Australia who invented a v twin two stroke but may fall through due to lack of investment. Its called cits engineering.
Interesting stuff as it doesn't need oil fuel mix and is direct injection.
Still make here. Yamaha Superjet is a twin cylinder 701cc. Very reliable motor. Very. Lol. Plus the twin cylinder sound is so much more sexy then a triple IMO.
I'll further add about cits engine, if you type up on TH-cam cits engine 2 stroke as the key words it'll have a animated info on the engine along with a dyno test of the engine.
How about going ringless? I know it might sound silly but let me explain. You could use your hidden pin piston great idea by the way. But make a tight tapered sleeve.Now you can use thermal expansion of a tapered piston to get the fit you need. That could give you the ability to run massive ports. The sleeve could be aluminum with a brass layer and then chromed with high nickel chrome. Because the the sleeve would be a separate part, it would be easier to experiment with ports. Nitro RC cars use sleeves of this type so we know this works just scale up. All though not ideal for long life, this could let you experiment more freely with rod length and port shape. If it is just for racing a fresh rebuild would be much faster new piston and sleeve would be easier to do not having to gap rings and hone cylinder. And with no rings you only need a small groove in top and maby half way down the Piston to hold oil to lubricant cylinder. But please look at Nova Rossi they make some of the best RC 2 strokes out there. Keep up the great work can't wait to see where 2 strokes go.
You know it's going to be a good video when you start up that heater. Winter time is 2 stroke stuffing time.
Electric intake valve like Koenigsegg in each cylinder (powered by a small alternator that also powers the injector) with singal turbo and fuel injectied but also make the exhaust port how your saying on the video. Idk if its stupid but what do you guys think of that? Are modern two stroke racing engines already using fuel injection? Just have never seen a turbo on one either and have been trying to think of a way and an electronic valve seams to be a way in my head.
In small model aircraft engines (the type that use the fuel you are already using), it is common to use a ring-less piston for a few reasons. When they go beyond 15cc however, manufacturers usually go back to ringed. The idea is that the piston and cylinder don't actually touch but rely on the thin layer of oil for a compression seal. Ports are huge and there is no ring that could snag. But there maybe more friction with this much contact area.
Go for it brother!! You have great ideas.
Thanks!
I know it's off topic but as a gunsmith I usually think about how new things in the gun industry can help with engines. Alot of heavy duty self lubricating gun coatings have made their way into the 4 stroke racing scene. I dont see why it shouldnt work just as good in 2 stroke applications. Like maybe using a nib-x (nickel boron) coating on the piston skirts. It kind of looks like a polished stainless steel coating but they are slick as snot on a door knob and carbon just wipes off. No solvent needed to clean them and they will work dry for a very long time at very high heat. I run a nib-x bilt carrier group in my AR. Add some oil and it should last longer than anything else in the engine. I've seen people run cerakote on the inside of their blocks to make it easier for oil to return to the pan. Guns and engines are both internal combustion engines. An explosion makes parts move to cycle the action either it being cycling a bolt and loading another round or turning a flywheel. These coatings can reduce heat, friction, and alot of other cool stuff with none or very little lubrication needed. When they are used in an engine that runs oil to lubricate it's just that much better. It's just something to think about or research. Alot of technology that is used in suppressors (silencers) should work well in engines as well like inconel* not sure I spelled it right but it's a very strong alloy that can withstand massive amounts of heat. They are often used as the baffles in a suppressors that are full auto rated for very powerful caliber guns. I'm sure there could be a good use for them in racing applications.
Thanks, very interesting! I'll read up on gun tech!
Had this thought in 1976 watching the night sky from 71 Mile House, BC. I wondered what might happen if you moved the compression ring down below the ports. Just thought I'd offer that one for your consideration. Crazy thoughts of boundary layer engineering never hurts. Occasionally by considering extreme adjustments we find what we were looking for. Although as the numerous possibilities were unraveling from your mind I did for a few moments wonder if having several wives might help put your project into perspective. Please keep at it, your thinks are getting thunked. Only when you load all the information you can will your brain surprise you with a few key eureka moments. Make sure you have a pen and paper with you always. Many of my best ideas came when I was consciously thinking about anything but driving. Funny how we remember every detail of our surroundings when we pull over to jot down an idea. Enjoy the process. Your videos are most appreciated.
Thanks! I wonder what would happen too. Ceveral wives would put things into perspective indeed...
Big bore big pipe big carb n nitromethane I am looking forward to seeing this before I go and do it myself
Would it be possible to let the ring fall out the exhaust port but design the port in a way it pushes the ring back in right before epc? Or maybe we need to scrap the piston ring and go with a whole new design? :)
I have an idea to eliminate the gap on the piston ring and use a full circle ring . This would involve making the top section of the piston a screw on top so you can unscrew the top of the piston and drop the full circle ring onto the base then screw back on the top effectively holding the ring in place . This will effectively eliminate the ring from spreading open if that design was implemented
What about an exhaust port that starts higher. Ramping open slowly at first, than maximum at the end of the stroke. How about making a piston that doesn't need a ring.
in Formula 1 engines, the piston i so tight in the cylinder. that is why they make so much power but they aren't very reliable
2STROKE STUFFING It´s great that you have contacted Both Atkinson and Niels, about the idea you have with the exhaust port, you should consider getting in touch with Luc Foekema
The vibration of the ring pins within the holes as the ring goes over the ports might wear it out fast. On one of my bikes the ring gap was passing right over the side of the intake port and bulging into it visibly so I filed down the corner of that ring end a bit and chamfered the port to a gradual ramp. It’s been like that for a year now with no signs of deterioration.
Nice ideas, I used one small boost port that opened first and it worked really good. You can still brake the pistonring if the exhaust is too wide even if you pin the gap. The heat deflects the ring in to the port if there is too much room for the ring.
Have you considered an opposed-piston engine? It would give you more port area, high compression, better control of timing, and good thermodynamic efficiency. The only downside is that you need two cranks geared together, or a complex linkage. So the rotational mass would be bigger.
Opposed piston engine don't have a "better thermodynamic efficiency", they have the advantage of a lower piston velocity for the same stroke but the disadvantage, wich results in a higher max power output but they got the disadvantage of a faster decline in pressure due to two pistons moving and expanding the chamber instead of just one (that would result in an overall torque loss). Overall, a great idea with some technical issues to overcome, i'm a big fan of the Jumo 207 d engine XD.
two pistons moving or one piston moving should give the same ""decline in pressure" for the same total volume and piston area. Fold an apposed psiton engine in half and you get this: en.wikipedia.org/wiki/Split-single#/media/File:Two_stroke_Valveless_engine_Animation-2.gif
@@fuzzy1dk
Yes and no, compare two engines with the same displacement and the same stroke (the piston travel) and you will see that the opposed piston engine will have a higher compression but also a higher decline in pressure, however when you compare the two engines with the same displacement and the same copression, you will see what you described in your comment, the same pressure decline and the same compression. So in short, depends on the comparsion ;D.
or you can do something like this
oldmachinepress.com/2014/02/24/michel-opposed-piston-diesel-engines/
it would have to fire both cylinders simultaneously unless it was a 4 cylinder. I think you'd have better performance with a single than an opposing... due to less friction loss, and less rotational mass... hmm maybe not? because the flywheel could have much less counterbalance weight. I'm not sure, further experimentation is needed for sure! and I'm a Subaru guy, I love horizontally opposed engines!
This is maybe a crazy idea but maybe it works.
If you have another crankcase as booster/supercharger you can get more horsepower because of larger crankcasearea it suck more airfuelmix in and boost it until tranfers open.
It can be made in light material and connected as a rotary port.
It is easier to explain on paper but i think you get the idea.
VCCG. Variable CrankCase Geometry 😀
You talked about the pressure built up in the cylinder causing backflow into the intake transfer portscausing problems. In the 70's didn't Yamaha add a vacuum canister by a port in the intake track to help eliminate this. I cannot remember but I think the volume is a relationship to cylinder swept volume. I added this to my motor and instantly noticed idle and midrange help, but in theory I feel it could help your problem. What if this canister were ported to the intake and also had its own set of small transfer ports. The volume could absorb inital large pressure blowback. Another way might be to have the canister ports with one close to the carburetor and one port close to the beginning of the transfer ports, with both on the intake track. I uses a 8 oz bottle for my 50cc engine, that was just on the intake track about 1 inch before the carb.
The other idea is to eliminate the bottle and port the initial pulse from its own transfer ports back to the intake, but port it to a nozzle to push the mixture faster into the transfer ports, sort of adding a supercharger effect. Has something like this been tried? Very little volume would need to be rerouted to eliminate the pressure blowback.
I am very curious as to what you think. I am no expert so if you can let me know your thoughts I'd appreciate it. Also I cannot find all your dyno videos for the motorized bike. I am building my own and need to see after the pipe was added, and and reed valve. Thanks.
bigger bored cylinders in 125cc +++ engines have bridged exhaustports.that should surely be possible to do on a 50 cc too. and how bout making a petrol 2 stroke in the same way a 2 stroke diesel is made(detroit) with valves in the head for intake and lots of exhaust ports around the entire circumferance of the cylinder? i know detroit uses compressors to scavenge out exhaust but the exhaust system does create a vacuum that pulls the burnt gases out.
@Tian kay ok,I dont see him use the flap system that raises exhaust duration so u get middle band and high revs also. suzuki rm 125 dirtbike has that solution and it runs very good. id reckon him adding that on his 20+ hp build could boost power and powerband ?
Very nicely explained. But are there two other factors to take into consideration? Such as the density of air molecules and fluid dynamics of fuel? Both are fixed and there must be a happy medium for finding the "best" sized pirts, etc. Thanks and keep us all thinking
Thanks! Yes, you are right. I think there's a point of diminishing returns somewhere, not sure where yet.
use low tintion rings and gas port the piston. this will allow the rings to expand on the power stroke and free ride on exhaust stroke.
Back in the day we used to run the autisa 65cc kits on the puch maxi and the piston ring would catch the ports when making great power so to fix it we removed the pins and drilled the piston for those little pin guides and re- installed them in the piston so that the rig gaps is in between the ports and that solved our problems of breaking piston rings hope this helps love your videos keep up the great work Aloha from Hawaii
I am working on a similar project. It is a 2 stroke toilet. I believe that it will revolutionize the toilet industry. My wife craps like an elephant and it has never been clogged. The inertia from the giant turds flowing through my sewer pipes then turns a turbine in a generator. I am running off the grid on free power from my 2-stroke toilet, and of course thanks to my wife's giant turds.
Awesome man!
Hammer head the exhaust port on small c.c this will not only help with increased flow it will also change the sine wave coming back from the expansion chamber. If correctly done will increase the charge pull into the motor.
Great to see your videos... The Evinrude direct injection 2 stroke outboard has lower emissions than comparative 4 strokes and is allowed to run on Canada's lakes with strictest emissions restrictions so it's well worth pushing the boundaries of performance and efficiency with these motors.
Gotta love the smell of twostrokes on a cold fresh morning. x
Just try the ring expansion limiter with wide ports, I believe if you get the ring to work with pins in the piston or possibly a ramp or two to push the ring back in then you will be on to something. And I forgot why you're trying to turn the cylinder 90 degrees for because if it's for power it probably won't help with a properly controlled ring and wide port setup but I don't know 100% if it will or will not gain from it .
I had a friend long ago called linden dash or dr dash as I called him,he was a genius like you
When it came to two stroke engines,always drawing on graph paper explaining porting and such like,at the time he was knife edging ports
And gaining more power,it's a joy to watch your video,keep up the good work,
Loving your total dedication to making stuff happen irespective of the problems that present to you , this is how man moves forward
Keep up the good work and I'll have a cigar in your honour
Cheers Gilbert
How high is he revving the twin ?
We know the 3 ways to increase power is raise CR or RPM or BMEP.
If we divide the 100cc into 2 x 50cc we can rev it higher since mean piston speed equates to stroke. (not sure if you saw my latest video on the topic)
Example
100cc swept volume with 50 mm bore and 50 mm stroke at 15,000 RPM is a safe 25 m/s mean piston speed.
50 cc swept volume with 40 mm bore and 40 mm stroke at 18,800 RPM is about the same 25 m/s mean piston speed too so with 2 x 50 cc you get an extra 3,800 RPM at the same safe mean piston speed and higher RPM equals more power hence I ask what is the peak RPM of the twin engine now..
Also regarding the ports.
The circumference of 50 mm bore is 157 mm compared to a 40 mm bore is 125 mm so not a huge difference and keeping in mind the ports of the 40 mm bore at 50 cc swept volume are proportionally smaller than the size of the 50 mm bore for 100 cc with less gas to travel via those ports in the 50 cc than the 100 cc, so I'm not sure if it is true that smaller engines experience greater short circuiting of the ports.
If I remember correctly he's reving about 22k rpm, here's the link, in dutch though... Very, very talented and knowledgeable people. www.deraceheldenvanweleer.nl/index.php?topic=1659.0. You're probably right about the short circuiting, in retrospect I think I was mixing in thoughts on small bore/long stroke vs big bore/short stroke stuff.
I had a look but its closed to outside viewing for some reason.
Ah, too bad. Try registering, if you can decipher the dutch instructions. I must have done so I while back but forgotten, used to be actively following alot of forums, need to get back in the game. Haven't watched your vid yet, looking forward to it!
2STROKE STUFFING Please consider using one of those crankcases which are almost closed and only have space for the rod, like the ones Kart engine´s manufacturers have been using lately.
Your thinking about smaller cylinders having more area/volume is correct, they will breathe better and make more power. Another reason is they can rev higher, which allows you to run higher compression.
As for the opening of the transfer, this is called staggering, and its an old idea. You open the rear (boost) ports before, they will have more kinetic energy and won't suffer much back flow. if you open then all at once, the velocity of transfer decreases, so they are more affected by back flow. If you open the main transfer first, the exhaust flow will carry the mixture out. The back ports are further from the exhaust so they are not so affected.
You can get a ring that expands with heat faster than normal and have it completely circular in shape and cross section, to seat against the walls, stop leakage and prevent from snag.
For that you must make a piston top that screws into the piston body.
Or just forget about piston rings altogether and make everything with very fine tolerances.
Have a ring with an angled bottom so that the smaller circumference of the ring won't fit outside the piston wall. That way it won't breach the cylinder wall at the port. The ring would have to be thicker but would still create good seal. Maybe, its been a while since Iv gotten in to engineering anyting in an engine. Just my thoughts.
You've got a CFD supermachine under your cap, man ! I never understood why I could ''see'' flows going throught a system but now you gave me the proof it is possible cuz I feel the same way as you for your enigma... Thank you for giving me the confidence to express my vision and stick to it. Usually people don't understand what I'm trying to convey them... Thx again
For the boundary layer effect, I feel the thickness is partially effected by the speed of the flow... But I agree that a 50 cc cylinder has a f**king relatively large boundarie layer...
And what about notching the piston/ring(s) just at the right place ? Instead of a straight dome piston design ?
Here is a challenge for you! Build a efficient 3-stroke engine. Skip the 4-strokes intake cycle and use high power fuel and air injectors just before compression. Catch the piston on the way back up and not down. You dont need intake ports, just a good placement of the exhaust port.
being able to build is well past important. it is the problem to solve.
there is the additional problem that the ring will float some on the piston
avoiding a broken ring is an issue.
consider skipping the ring. hard to start however.
Another is keeping upper cyl to lower cyl in alignment... under load.
the exhaust bridges will get well past hot so it needs a certain size to be able to survive
You could probably graph engine size vs output for a number of racing engines and note a curve. You are right that boundery layer, air density, speed of sound... are not scaled with engine size, also flame speed goes with the fuel used.
The Two Stroke takes its toll in Bottles of Whisky!
I think you could solve the problem of intake and transfer ports and pistons rings snagging in the ports if you would go to an oval piston with to connecting rods
Could you put some serious angle on the ports so the ring is effectively only ever in contact with percentage of the total length of a port?
To some extent, but area will suffer.
Could you make a ring that is wider on the intake side verses the exhaust side? By being wider on the intake side than the exhaust side, it would be limited by the piston on how far it could bulge into the exhaust port. Pretty much an eccentric ring. Of course you would need a good chamfer still on the exhaust port.
Trying to retain an expanding ring from the inside of the diameter of the expansion of the ring will not work by only using two points of retention on the ID of the ring itself. Minimally you would need three points. Very cool idea though. I hope it all works for you in the end!
Have you thought about grinding small dimples into the intake channels after the carb? similar to golf ball dimples?
If you did then the boundary layer is less because with golf ball dimples you get hundreds of micro eddies forming
Picture a Formula 1 air splitter for your exhaust port, top & bottom with relative scale changes A better discription perhaps is to picture a traditional port bridge and place one, say every 15mm of horizontal port. If you consider how bridges are often relieved across the span, for heat issues or whatever, and if ring snag is the only function of the bridge you wouldn't miss the span if it disappeared completely. After all that, the port would have several "Ring Saviors" (test driving the name, out for a spin) guarding the port top & bottom. Saviors could be created to be en guard at 15 to 20mm intervals. With careful tapering and profiling there may be an aerodynamic benefit to a port who's roof and floor leave the bore with a well guarded arsenal. Maybe the exhaust likes being grouped into defined rounded squares when it makes it's cylinder departure.
Thinking about retaining the ring as you were sharing earlier. If the ring gaps are pinned to stop rotation and let that ring gaps be at 6 o'clock. By limiting the ring's usable groove depth at 4:30 and 7:30 with tiny pins or aluminium nibs as noticed on 1975 RM125 piston top ring groove. The desired overall centering of the ring would benefit.
A sketchs require so few words. A A good sketch could be worth 700, 800 words, at least. Just discussing the potential and value of a good sketch with one or our Border Collies. Oh yeah, 1000 words per decent sketch.
Love the New Territory project. Looking forward to much more. Cheers.
Well that's different, can't scroll, proofread or send. Tappity tap tap. Please go
That was very humble. Every thumbs this up. I appreciate stuff like this sorry. Love from Canada.
the wall of the ports should have angular impressions rising up, these fins so to say would create channels of rope like vortexes that would gather in the middle and create one vortex that pulled the spinning exhaust now organized to the center away from the ports walls, the gases would be sucked out instead of blown out.
Cut valvular conduits into the piston, flow direction towards combustion chamber.
To accomplish the building of the perforatted cylinder wall install a polished steel cylinder with perforations that would line up with the larger open ports, In the aluminum head.
Hmm, why not just extend the exhaust port to say 110%? Ie past the center. And keep the bridge(s). That'd probably give you the same area. My gut feeling about your plan is that the ring is going to catch no matter what because it has no support at all on the exhaust side and the piston doesn't need to rock all that much for the top of the piston to go inside the port. But I've been wrong before :) Either way it's a very interesting idea!
Thanks, I need to find a way to get this tested without selling the house. I know bringing the aux ports past 100% was tried by someone (Jan Thiel?), lost power, probably due to short circuiting.
For testing piston rocking I could bore and hone you a piece of pipe to whatever size you want and you can put ports in it and test with just a piston.
Thanks, that would be great. Wonder what kind of clearance best resembles normal running conditions? Should maybe heat up the piston before testing too.
I think you should probably test with the largest clearance it'll see, the piston is going to be rocking regardless of temperature, I think the accident risk is probably the largest when it's cold and at low rpm.
Sounds like a good plan! 40mm should do, let me know when you have time.
Have you considered lapped pistons? They can be made to work very well..... and no rings means no trapping in the ports....
I did not read all the comments. Maybe someone mentioned it already. Could you use the pin or pins on the exhaust side of the ring maybe with an elongated hole so it can move in but not out? Let the rest of the ring act as it normally would.
What about testing another kind of material for piston rings. And make them even thinner and rounded...o-ring style? Or rounded on the side against the cylinderwall...
as a toolmaker i see a circlip drawn on the page at14:01 sitting a fare distance away ,at full screen i see a piston ring with tabs
Could you make a 2 part piston and sandwich the ring in between them? Like a complete solid round ring? You can even have two materials for the top of the piston and the bottom of it...
Actually, I thought about Ring expansion... could the ring be made in a coil like matter? As it expands, it twists on itself🤔
I have spent the last 20 years of studying the evolution of the two stroke engine. And a student of Dr. Neels.
THe problem you are talking about was thought about and overcome by the engineers of Yamaha when the made the case inducted TZR 250 V engines. The V configuration solved this problem. Off overcrowding of the ports.
Most of what your saying makes no sense. Because some of the most powerful engines per cc are the little 7cc two stroke. I did most of my learning on these little engines as they are cheap to buy and service.
Multiple transfer ports work better than just two single or 4 port. Proved in the 6 transfer ports as found in the TZ350G.
This predates the tea cup shaped transfers we see today.
Aux ports are very important as is the little hook in the aux ports introduced by Suzuki. Copied by Yamaha. Because these create a twisting upward movement. The radial and axial angles of the transfers are also critical and Neels s/w calculates their effect on charge purity and scavenging. You cant do good scavenging without a boost port and aux port.
ANyway nice listening to another two stroke nut.
There is also a number of other problems :-) one of them is friction…..i made some tuned engines 20-25 years ago, and removing some of the friction made a "leagel" (restriction still mounted in intake) moped go from 35 to 50 km/t ;-)
12:45 the only issue I draw with this idea is what do you do when your rings wear down? if you build the slack into the ring when new isn't there a high chance that it'll still snag on the top of the port enough that it could break off? or would shaping the upper section of the port to ramp the ring back into the bore be enough to prevent the ring from snagging on return for the compression stroke be possible?
I always wondered about using a standard piston and wrist pin and cutting a thin piece of thermal blanket (or something) over the end to allow room for expansion of the pin and then welding a plug over the top and turning off the excess. A cheap way of making a sealed pin, if you have access to a lathe! I love your ideas, may they keep flowing.
Yes that’s the issue with multi cyl small CC’s. Port crowding and interference. However if you get twice the port area and can you make them up to 49% smaller & you are still ahead. It would be great to have a 3 or 4 cyl 50cc just for shits & giggles as we sat in Aus 🤙🇦🇺
What about threading the bottom part of the piston using a shallow/narrow thread? That way you can use a piston ring that has no divisions. also, if you extend its lower part, you can also, cover the piston pin evenly, if desired. it would avoid ring snugging and allow a large exhaust port, also i think it would be a more structurally sound solution, would more likely be able to withstand larger stress.
Thoughts? can also make a sketchy sketch for you, if needed.
You’ll need a cylinder that can accept sleeves. That way you can custom cut any port timing you want. Probably easier and cheaper that having a whole one off cast cylinder made. I’ve got high hopes for you.
Also couldn’t you just use a piston with only one pin hole? Push in from one side and retain with the normal clip. Some nitro rc engines use plastic balls in place of clips. That would seal off the pin area. Might be a possibility
How about to scale up the r/c style of cylinder thats slightly smaller around tdc and wider at the downstroke in the bore and go without piston ring?
I used to have an 4.25cc rc model engine, running on methanol. They use no piston ring at all...only thing cilinder and piston where an match, you couldn't swap out. So if you use the same materials they expand the same way while warming up? And an idea i had was 2 rotors left and right side. 1 carburetor. An intake manifold 1-2 style...But 90° turning the cilinder never crossed my mind...
For the custom cylinder, look in to "lost PLA casting". I've got access to a nice 3D printer we could print the cylinder on.
I've been thinking about it for a while. Any experience with it? Good results?
@@2STROKESTUFFING I've researched it a lot and have been wanting to cast a cylinder using this method. Haven't got a chance to draw up a cylinder yet though. It would probably take me a day or two to draw on solidworks
This would be a similar process to a water cooled cylinder:
th-cam.com/video/HVgPM1ojyLw/w-d-xo.html
In very small cylinder the travel distances of the gases are short. This makes possible to use higher revs. Also the ratio of the hole areas to volume is bigger. We can see the benefit of the small cylinder in small RC airplanes. I like to see how the system with two exhausts ports works. To make the traveling distance for gases short is to put the exhaust ports on the different sites of the cylinder. You need then two machine made exhaust pipes to quarantee the pipes are exact the same. If the piston speed is high also the gas speed is high. Then the gas pressure hit into channel is small according Bernoulli law. When having relatively low channel the piston is near the BTC and the speed is slow. The gas pressure hits into channel more than high channel. I hope you understand my poor english. I like to watch your programs. Thanks!!
Why not go for a broken ring with no ring in that area? Power gains would exceed compression loss. Do the hook design on both sides of two ring sections
This may be completely ignorant, but what if you just put the piston ring lower on the piston?
I figured it is going to get blow by as it passes the larger port anyway, so by lowering it, you have no blow by.
What about a 1mm line down the cylinder wall where the 100% port is? I know its no longer 100%, but it stops the ring from springing into the port.
I fear that line would overheat fast.
Great little video,
Loving your content...
you could still go twin cylinder with a fairly large bore
All you need to do is a much shorter stroke ...
This will allow you higher revs as well...
Keep going I love your Chanel
Romain
Thanks! But with larger bore vs stroke you loose port area... No free lunch...
And u will lose torture as well at 50ccm u haven't much of it
Hehe high revving big bore, short stroke twin, AKA Formula 1 two smoke! LoL
Low torque value? Depends on what you mean, there is a difference between low and high end torque. 50cc and about 10-15 Nm @ 15k rpm thats about 20 horses.
Hiya,
Have you considered two opposed exhaust ports? I've not seen it anywhere, but I can't imagine that it's my idea, or that there's some reason why Mr Yamaha isn't doing it? it just seems to me that you would get more blowdown area without the ring support issues and I'm sure the transfer ports could be configured to suit?
the expansion chamber (or chambers) would look interesting??
Happy tinkering!
Good idea! Check out Frits Overmars' FOS concept!
Hi had you thought of the similarity between an aircraft engine's flow character and the flow of an aircraft ducted fan with its boundary layer and laminar flow ?
You could research this to help with your calculations for better flow and the effect of turbulence and laminar flow relative to the boundary layer ..
maybe this would help ? Cheers good work and carry on improvising your design .
take a look at 1-3cc model nitro engine. It's all about scale. 1cc engine or 500cc 2stroke all have ports. Of course small engine is small on separation area
With a 180 degree exhaust port and no bridge I think the entire piston will rock so the upper ring land will hit the top of the port, not just the ring.
That's a concern, yes. Will perform a test soon.
Maybe the exhaust port could be 2 ports right next to each other to alow a bridge so the ring doesn't catch??
Just a thought, take a look at nitro rc engine cylinders. Some standard engines only have 3 ports. But some racing engines use 8 ports. Maybe using a port designed like the nitro engines would work?
Do to a rc nitro engine being similar to a rotary valve (instead of having a valve they use a port in the crank) it might just work?
Ok, whats happening is the cylinder porting will not progress very much from where we already are, the limitations have been met because of the actual physical shape of cylindrical nature and the limitations of piston travel/linearity.... the best direction to go would be supercharging and manipulating spark timing .....fun stuff for sure
Idk perhaps thinking about the shapes of the ports and how one could shape a 100% exhaust port to provide as little to catch as possible, the bridges will still need to stay though I think- at least two.
Wait a second, i believe that the blowdown area you are suggesting gives the burnt gasses enough time to flow out the exhaust port and equalise before the first transfer port open, so you will no longer have the backflow that you where suggesting. I think its just a matter of having enough blowdown area for the defined amount of blowdown time to be able to let all exhaust gas pressure escape before transfer open.
Lets put it this way...
Traditionally there is usually much pressure left in the cylinder when the transfers open, but with your humongous exhaust port area i believe you will overcome that problem.
I have a calculator/simulator program in which you can experiment with exactly this problem aka backflow.
You are right, but. The humongous exhaust port will probably eliminate backflow at the original point of peak power, but due to the increase in blowdown STA there will be potential for a new point higher in the rpm range. This new point will suffer from the same backflow(and hopefully produce more power).
The ring idea would be very hard too do for one how do you fit the pistons and rings in the jug without compressing the rings and second how do you get proper compression
Very hard but not impossible!
Unless your going to put a ring land and an additional lower ring at wrist pin height your really not going to gain much. Or are you trying to increase the fuel charge by covering up the pin?
I could be wrong but I don't think you can pin the ring.. it needs to expand .... right??
Yeah? Thats why we've got the ring gap too
You already have a pin for the ring on two strokes... it is there to keep the ring from rotating as the piston moves up and down so the ring ends does not hook into any ports. The pin is where you put the ends of the piston ring. If you look at a 2 stroke piston ring you see the ends are slightly notched to accomodate for the pin
All you have to do is move it to another place.
If feasible it would be restrained just the right amount for it to work properly, but not snag.
The question I have is how are you going to bend the ring enough to get it on the piston without breaking. I have enough trouble with a regular ring that has no tabs.
This would be the step beyond a 100% wide twin or tripple, even more area and better flow without bridges.
Since your having a custom piston made. Would it be possible to have a ring that was solid no gap that could be seated then the piston lower skirt thread on to the top of the piston making the piston with a ring with no gap?
LOOK AT THE DESIGN OF ***TOTAL SEAL GAPLESS RINGS**** use this concept with your pin idea working from both sides of the piston to contain the ring from both sides ...then utilize a ( L ) shaped split ring design , and change the design to keep the rings from passing each other and from expanding outward....... using the L shape or a C shaped ring to keep them in
Can you make a rotary style engine for a dirt bike..? The power in Mazda's rotary design is absolutely crazy.
Port size on a small bore is relative, its all about proportion.
70% of bore for exhaust is enough, with the little ports outside that.
I did think of and just worked on a engine with ports 90deg like your working on.
Small single two stroke outboards. They are cross flow, not loop charged. Clinton and Tecumseh.
piston rattle. Maybe put in thick ribs at an angle and rifle the walls so rings spin naturally. Think leaning hashtag cylinder wall. just ideas... Altering piston and ring is a bad idea to get port idea working.
If you would make a "perfect" Ring wich couldnt expand much, it wouldnt last long. It needs pressure for sealing. After it grinded itself a bit, you would loose compression.
If you want to give it a try, look for a company wich has Wire electric discharge machines (Wire-EDM).
Have you ever thought about using a tougher material for the CylinderWall? Maybe you could put a round steel-insert into the aluminium, so you could make the walls between the ports thinner?
Just spitballing about boundary layers. The Olympic swimmers have had their "sharkskin" swimsuits banned because they reduce the drag on the swimmer so much that it's seen as an unfair advantage. Would it be possible to replicate "shark skin" in the port wall thereby reducing the drag that forms the boundary layer in the first place? Another thought is golf balls. They fly further now due to the dot pattern on them reducing the drag. Same result, different method. As I say; spitballing to possibly trigger ideas.
Good ideas, worth exploring!
Would you be able to install a pinned ring piston into the bore. Would there be no compression of the rings to get them started?
Look into L rings for the piston. With that design you would have more material on the ring to make a recess or hole in the ring without weakening it as much along with the high rpm advantages of an L ring.
Suggestion: I am not a mechanic, an engineer, nor a machinlist. But if you are capable of making your own cylinder why have not have even larger ports to the exterior of the cylinder but on the inside have a solid wall with staggered drilled holes in the inside of the cylinder walls...like Swiss cheese. That way the air intake and exhaust can easily flow through the holes into the larger exterior ports. That would solve the problem of the rings expanding out of the cylinder and breaking on the edge of the port. The larger ports would be required so more air could flow through the drilled the multiple holes at the same volume as the regular open ports.
I hope I made my idea understandable to you. As I said, I am not a mechanic or engineer...I just like to tinker.
The only thing I see that may go wrong with a screw on piston. On 4strokes piston rings naturally rotate around the pistion while the engine is running. 2strokes have a pin to stop that piston ring rotation. Or at least that's what I was taught in school. I'm thinking that this may cause the piston to unscrew from the rod. You should have him build a piston and rod for each thread direction. I may be wrong though, but just in case I'm right it'd be nice to have the second piston and rod.
His design have the two pieces secured with pins. Clever guy, thought of everything!
@@2STROKESTUFFING
Yeah he did.
yamaha and suzuki tried these designs you suggest in the seventies. Suzuki had a road bike with bridged exhaust with auxiliaries but yamaha always managed more power with a single large port. I always thought yamaha managed to tune all three systems: in, transfer, ex ; to work together more effectively. Until suzuki came along with the RG! Have you ever read "2 stroke tuners handbook" ? The author discusses boundary layers and the effect on different shaped ports, also transfer port design . . He went to the effort of predicting with maths various design parameters. best wishes.
I saw the piston it really cool.In some 3 or 5 port engine it's fine to use std piston.Thank you 4 the simple but most important Port bridges.
What about having the intake go directly into the crankcase?
It does. Maybe you've mistaken the exhaust for the intake?
@@2STROKESTUFFING no no im saying what if you cut a hole in the crankcase to allow the flow directly into the crank, it might require a richer oil mix but just think about it
If this communication through the piston pin is an issue would filling the pin with a high temp silicone give results for existing engines?
I've always wondered how hard would it be to make a hybrid e-bike with a two stroke generator and does it make sense at all.
I wonder how many people realize what your saying? You are gonna do some amazing stuff keep going
Thanks!
What if you just kept the same bore, but a much shorter stroke to get the same displacement?
The solution to the multi-piston problems is simple. Make the engine 500cc instead of 50.
Joking aside, I am curious to know where the actual ideal cylinder size for maximum specific output is. Given how vicious these 50cc engines are, I bet that's not far from the mark.
I think it will be too prone to rings shattering ..even with several workarounds i have been thinking of I keep coming back to the fact that the heat expansion of the cylinder and piston require the ring to be free floating.. basically.. the bigger the piston circumference the more important that becomes... a Part of me wants to say don't bother because you won't gain enough hp by removing the port divider and extending it that far to make the venture worthwhile ...but having said that ,,.. im not so sure either.., so was thinking there is a way to try it, plus maybe a different way around it ... I have a heavily modified (by hand) nitro two stroke motor with every modification imaginable basically including port mods knife blade con rod etc etc and there are some tricks to porting you can find in DIY guides on youtube that would help enough probably ... you could get a rc nitro motor (they have no rings) ... run it in and hp test it, then add your port design and retest it?? ..or just try what your thinking and destroy the piston, cylinder, head etc a couple of times over while getting the ring holding pins/springs perfectly designed.. then find out the real advantages/disadvantages of your port change...
I see your point, but watch my latest vid!
I just watched your latest vid. I hadn't heard of or thought of the step ring idea either.... it's one of those ideas that makes me think "wow, why has no one thought of that before" ... lol ... anyway ... about your comment to stop sharing your crazy new idea's to try, it's fun for us viewers to consider the implications of them... and anyone intelligent knows plans change with improving and building things like you are. I like your vids, good work. I can't wait to see what power gains your end product produces.