As an old British 50cc and 125cc motorcycle road racer from the 1960s, I really appreciate your videos. I raced in an interesting era when the 4-stroke engine had to give way to the 2-stroke’s superior horsepower. Although compared to the 4-stroke, 2-strokes were tricky to ride with their extremely narrow power band. This necessitated 50cc bikes having 12 and even 14 speed gearboxes, and a usable rev range of around just 350 revs. So it kept you pretty busy! I’m a retired British engineer, ironically living in Oslo! I’m now in my late 70’s, but still very much a 2-stroke fan. Keep up the good work. It would be fun to meet you sometime, lykke til, Michael Leary
Allahumma shalli 'alaa sayyidinaa muhammad wa'alaa aali sayyidinaa muhammad wasallim tasliima😁😊 Yok Tobat Kawan Dan Jangan Lupa Sholat Dan Sholawat😊😁😊😊😊😊
I think he meant to write something about having vision and perseverance which is what I see here..easy is worth alot. Especially when your working alone. To me anyway, I think the message he wrote was to himself stay motivated
@@davidbeer My garage hae very very thin plywood doors and I hot angry pecause I fucked up a bolt that holds the head on place. So I threw 23mm wrench thru the plywood door and it hit my liltle brothers elbow who was playing on other side of the door
Normal rings,normal double porta ex and he will fly,because the main idea head is primary Reed intake and flat valve full opened intake with injection ad secondari. He forget that concept and loose time with no sense exshaust port that broke ring in a minute..
@@vnsworkshop9961 A Super high Perf 2 stroke gets by on 1 piston ring.Ask any Japanese engine manufacter.Trev New Zealand (repeat holders of the Americas Cup )
Martin...many have !.If he sticks to a Reed intake & dual long timed Ram tuned Rotary valve that with a shot of No2,That should work for him- needs to build a little dyno 1st.Cheers Trev New Zealand
I too am an old 2 stroke racer from the 60's when we were developing fast bikes from slow street bikes. Very innovating ideas with the captured ring. I ran an exhaust port shaped something like a T. I imagine your exhaust port shape is designed that way for scavenging purposes. Also ran a dykes ring. Too much friction??? Seems a larger ring would be easier to hold with your captured ring system. Also we had a graduated chamfer on the top of the exhaust port that eased the ring in a little less abruptly. Love this two stroke stuff! Thanks.
Just remember if you put a bridge in the exhaust port you need to drill holes in the piston for lubrication and cooling. Otherwise the bridge will heat up more than it should and it will snag the piston.
Note:. Bridge in exh should be hand- relieved back from bore by approx .004". Been doing this on kart open motors and controlled motors for decades. Works great! Zero issues. Oil holes in piston will be Much Less necessary!! * Best exh port is 3 port. Large " oval" with "well designed" side ports. Keep champhering to a minimum. Port opening must be incredibly parallel to ring!!!!!! CRG MAXTER 50mm bore on last motors developed, were fantastic, durable. Piston skirt needs to not impede feed into side fransfers. Etc Etc Etc Keep up the good work!
You're a legend roughly 2000 dollars for a single cylinder that you designed thats amazing you've put so many hours into research and development I look up to that
This has all been done before. The numbers for max port width in a ringed engine are well known. At 50cc you might try to eliminate the ring and go ABC although, the piston expansion rate would be tremendous.
Try a ring like a total seal design. Make a ring with an inner lip. Then use a ring that catches that lip to hold the ring in place. It has no gap but is smaller diameter so does not contact the cylinder wall. Now no uneven parts on the contact ring. Contact ring should be very light contact. Almost zero tension when cold. Ring and engine expansion when warmed up will provide proper contact. You will need to pump heated coolant through the engine to provide enough ring seal to start.
@@mrsnezbit2219 Bayer lost its trademark rights to Heroin under the 1919 Treaty of Versailles following the German defeat in World War I. It is no longer enforceable. I know you were joking but I found that an interesting little fact.
Run a ringless piston and run nitro or alcohol / oil mix keeping piston cool just a thought. . Cylinder has to be tapered smaller at top and wider at bottom for ringless piston set up ../ \ ..
Hi, I needed to leave a idea for you to consider: You could taper your sleeve and have a tapered hole in your cylinder. Just like a morse cone. This will give you the opportunity to switch sleeves with ease. Clean out carbon from between the sleeve and cylinder, hampering your heat dissipation. Moreover pressing an aluminum sleeve into an aluminum cylinder will not be easy, you run the risk of damaging both parts. Jan Thiel also did this with some cylinders, I do not recall which exactly, but I guess you know his work well ;). I hope you get something out of this suggestion! Good luck! P.s. This might help with timing your sleeve as well. You can fit it, drill a hole for a pin in the top surface of the cylinder, and fit the sleeve even exactly the same every time. Downside will be that the sleeve will need to be very precise in order to get the heights of your ports to line up!
Right on Guys for giving suggestions I only know of cast iron solid cast small blocks. I was going to suggest a diff. Composite of ring. I am outa my league a lil. Thumbs up to the producer the engineer and the star of the show.B.t.w Do not bore the hole 2 big possible ROD problem. G.L.
Build yourself a 90%/10% nitromethane/methanol burning hemispherical billet 50cc engine with twin spark plugs, and with a twin screw supercharger, and mechanical fuel injection. I'd learn the secrets from the types of Brad Anderson Engineering, etc, then apply that technology to a 50cc build. This would give you fruition to your goal of having the world's most powerful 50cc engine.
This is great Alex, I’d forgotten about this project you were working on and it popped up on my TH-cam feed. The last time I seen you on here you were casting the engine. You are doing a great job. I’d love to do something like this.
I know thicker rings aren’t great for power, but I seems like a ring double the thickness with chamfers on both sides would alleviate some problems. The ring/cylinder contact would be about the same while allowing the ring to ramp over unsupported walls.
for the 100% bore exhaust design, have you considered a spiral piston ring design(essentially overlaping, all the way round twice)? with tapered ends tapering towards the piston on both ends during the heat expansion the ring simply slides the edge that is on top, and the edge that is on bottom towards each other but they can never meet, and it should require no locating pin(hence the tapered edges, the piston would need a deeper ring groove, and wider rings I don't quite know how to explain this idea, and I have no drawing skills so hopefully what I've said puts forth the idea correctly, I can't find anyone whos done it before or any designs like it online essentially a piston ring, but the edges keep going around another turn one under one over
Fantastic Videos, really appreciate your work and it has given me ideas for my projects. One thing - you may have already thought of this - 100% exhaust can still be achieved by adding the thickness of the bridge to the dimensions of the port width = 50% each side of the bridge.... you could then have two bridges if needed.
@@trevinskiking2165 ??eehm, sure?? and, what has that to do with anything, especially the topic? just asking, because some people comment on vids, some dont, regardless of them doing stuff or not... greetz, Stoeppel from Germany
I know it has to hurt to lose the full width exhaust port, but you may yet be able to come back to this idea for a visit later. Something in the back of my head is remembering pistons that were plated in a particular fashion that allowed them to be used without rings. Something about expansion and contraction rates the would match the cylinder closely enough that rings were not necessary.
Hey man, love your work. I would suggest making your cylinder sleeve out of cast iron or brass just for experimentation purposes then go with plaited aluminium later. Cheers. 👍
Your problem is that the ring is releasing its spring tension into the custom oversized exhaust port. As the tension on the ring expands into the original port it is contacting the floor of the port. You need to put at least 2 port bridges 1 may not solve the problem and the risk will continue to exist. 2, 5 to 7 mm chamfered bridges in the port will solve the problem of the ring releasing its spring tension into the port. A thicker ring might also help. If you are going to supercharge it you might want to use an "O" ringed head and cylinder design to seal in the extra charge. Also you might consider a thicker rod and a larger piston pin design. A very thick rod will ensure large amounts of charge into the combustion chamber does't cause breakage at high rpm and may allow revs up to 15,000 rpm using 10 lbs or more of boost.
Me neither, and I realized there's suitable small roots blowers available which could be used as a start. Working on not having my builds drag out soooo long...
A sensible move to drop the bridgeless port idea, you have chased your tail on that for so long and nothing so far has proved reliable. Keep up the good work, Kia kaha.
Before I watch. Congratulations! Edit: Thankfully, the words I now live by are written on your wall. You are an amazing example of resilience. Keep going. You have a great proof of concept. All of this work is something that you and all involved should be proud of. Nothing worth doing is easy!
Or Frits Overmars' FOS-cylinder... I've never seen anyone pull off the scavenging with this layout, hoping my brute force supercharger approach will circumvent that issue.
@@2STROKESTUFFING I’m a bit puzzled about that as well...since the first time I saw Frits sketches/prototypes I have really liked the idea. 👍 One thinks someone would have solved it by now. 🤔
@@andli461 It's harder than it seems I think. So many things that can throw the symmetry off. Uneven heat distribution, small imperfections in the transfer ducts, case turbulence etc. Such an elegant design though, and now I'm going to defile i with a supercharger....
There is a way to Turbo charge or even supercharge this engine too. you would need to install a rotary valve in the exhaust port to rotate the same speed as the crank shaft: - thus acting as a valve. open on the down stroke, and close on the up, then use a roteryport timing disk, to open on the up cycle, closed on the down. think youll get it. Youll need use a tiny turbo charger, and use fuel injection. with dialed in timings compression ratio, maybe lowered port height. (can also use more of the power from down stroke too!). Just a thought but think it would work.
Never give up! The exhaust so large was a gamble but you tried, now you will have the optimal solution 👌🏻 .. I await the moment that we will hear the engine spinning fast!🙌
if you use a supercharger, does that mean you no longer need the crankcase to do the pumping?? does the fuel+air charge go straight in to the cylinder?
You’re a LEGEND in the Making Buddy…. Good Luck with everything, I truly love watching & learning more about how you’re getting SOOO MUCH HorsePower out of engines Sooo Small. By watching you work on these Small Engines, I’m learning more on how I can get more out of Bigger 4-Stroke Engines which I work on. I’ll see you again, next time 👍
Did a lot of work with 2-strokes back in the 90s. Found that super-charging only provides over-scavenging and not much else. Turbochargers, on the other hand, add that essential back pressure to increase cylinder pressure, and power. Good luck Alex. We were running and testing a V-6 twin turbo 2-stroke from Jaguar. It was a blast until Ford bought Jag and canned the project. But heck, the power!!!!!
Hot gasses move a lot easier than cold gasses hence 4 stroke exhaust valves are always smaller than the corresponding inlet valve, a bridged exhaust port is not going to hurt the project.
Do you NEED a ring gap? Lots of oil to start it with a "loose" ring. Maybe a glow plug to preheat the cylinder and then swap in a spark plug when she's good and warm? Coolant preheat too maybe?
Surely the locating hole in the piston ring needs to be sufficiently inside the inner circumference of the ring itself so you have the full width of the ring all the way around and eliminate week spots like that as from what I can see the hole intrudes into the width of the ring as it is now. Hope this helps.
Before you add that sleeve, why not try a standard style piston and ring to see if the port will work with a standard piston. You can always go back to the three piece piston later. Would be cheaper and quicker, just a thought. Love your videos!! Good luck..
Thanks for sharing this with us. Have you thought about harmonics breaking the ring? The shockwave coming back into the cylinder. I was wondering why it would break at that point? Twice? Could it be a defect in the hole in the ring? Maybe you can try cutting the small hole with a laser. This is very exciting to watch. I grew up with mopeds in the 1970s. All of my friends had them. I had the fastest. One guy had a quicker one because he had it two speed. But I could take him in a mile run. it could run at 52 miles an hour on flat ground. It would go over 60 down the bridge On the way to the beach. I live on the east side of Jacksonville Florida. 13 miles from Jacksonville Beach. It sounded like a bad ass chainsaw. I had a puch engine with a Jawa cylinder and piston. I made a spacer plate out of brass. I took the pedals off and had a piece of 3/4” all thread with foot pegs on it. Straight bars. Long seat Suzuki tm 75 front end. Tomos rear wheel. 17mm racing carb that faced frontward. It was fast and agile but a itch to push to get gas. I would pass school buses going to school. Everybody was like what the fuck. It wasn’t pretty but it looked cool and one day I came home and my mother had given it away. Along with my two Honda motorcycles. That sucked but my dad gave me a 1964 1/2 Ford Mustang. He told me you can’t screw on a moped. And I can tell you that it’s a pretty tight fit in the backseat of a Mustang.
Your commitment is stellar, there's not many people that can keep motivated to finish a great idea. I guess that's why I keep watching I'm always full of dumb ideas, very few ever get finished.
I agree to thin of material on the ring at the locating pin you should only need a thin maybe .5 mm wide bridge maybe 1mm thick into the exhaust port just enough to hold it in place
Keep working at it man. I think keeping the single bridge is key to keeping all the flow you need. Unfortunately the ring Gap has to stay up against the bridge. Excellent video I'm a two-stroke fan from the '80s.
Worked on a competition RX2 motor in the 80's and it just chewed up apex seals at high rpm. Made the single port a "bridge-port" resulting in a crazy increase in engine life. Have no idea what the power loss was because we could not get the single port version to last long enough to get to the dyno.
I hope that set screw won't become an issue. I'd imagine possible bulging of the side of the piston if tightened too much or it getting loose if not tight enough... How does threadlock manage with heat?
Put bridges in the cylinder but make it less than the thickness of the cylinder wall. Maybe a quarter of the wall... just a support for the rings and it won't affect the flow that much if it was thinner than the wall cylinder. I hope a made sense and i tried my best to explain it. Cheers
I love your dedication to this build, I would not have had the patience to get this far... But I do feel like I just watched a movie where the good guy dies in the end.
I would use more than one bridge on the port. Even with the retained ring piston, you need to spread out the load to ensure you don't catch a ring on the edge of the port...even with a good chamfered edge. You will get a lot of ring wear where it contacts the bridge so make the bridge/bridges wider. Good tunes while doing the ring filing :). Huge advantage of going to a case intake is you can eliminate the intake port entirely...which I think you have done already...I still think a rotary valve on the case intake would work better than no valve to keep the flow from reversing.
Lovely Video, as always! I absolutely love watching you do 2 stroke things, i am totally sure you will find a way to get the most powerful 2 stroke ever!
I been there. When wide ports failed or resulted in poor ring life I shifted a bridged exhaust. When that also gave me heat transfer issues (being an air cooled engine). I finally landed up with 3 ex ports. One main and two aux.
Not sure if this is what you mean by bridge but what if you were to seperate the exhaust into 2 seperate holes so your still drawing the same amount of air out but the hole isn’t so big and makes it less of a ledge in one place for the piston ring to catch on, just a thought, Im not sure how doable it would be!!
Keep rocking brother you will get it, I know it's possible, I built a killer weedeater, still fs 76, it turns 14000 rpm, and after 2 years of me abusing it, still kicking ass 33cc I think😎
I really admire the cleverness of widening the exhaust port (with central crossbar) to gain pressure on the piston during its descent. Of course at low revs the performance would not be optimal, but, I must say, that I have not followed previous videos (for now) and I do not know what comes after ... maybe a throttle valve ... You put the ring in crisis all the same, especially at high / very high rotation speeds (among other things, it is better to make a classic stop :)). I would propose a somewhat drastic and evolutionary / revolutionary alternative solution ... You could take out the exhaust port at gas pressure and just drill a relative smaller round hole with an electronically controlled actuator and valve on the outside (depending on the rotation speed). To it you create a constant +/- intense vacuum (perhaps with a little compressor that you always send to the drain, connected to 'Y'). At this point, the expansion exhaust is not even needed, a straight pipe is enough ... there is no more back pressure and the fresh mixture does not escape. All the defects of the 2 stroke could be removed and its merits enhanced. know, it could be crazy ... or not ...
I know it probably won’t idle well at any low engine speed and may require some exotic coatings, but have you considered keeping 100% bore exhaust port but making a piston with NO ring like a glow fuel nitro engine?
Thanks for the reply 👍 Ok cool & understood; the only reason I recommended it was due to you planning to sleeve those cylinder, which would give you the option to go ringless like a glow engine, and the sleeve be replaceable, if it doesn’t turn out, or became damaged / worn.
Hi. Since you are using resonance, Isn't it possible to completely bypass the crankcase, drawing in the mixture through the sides of the cylinder head. Directly, you might then be able to introduce the mixture at what ever angle suits you without having to turn any corners through the ports. Obviously this would give oiling issues but might bring more efficiency in terms of flow?
@@2STROKESTUFFING I'm mad on two strokes and absolutely love what you are doing, can't wait to hear it sing at max rpm. Blew my mind, the whole open crankcase resonance thing. The switch from carb to resonance is going to be gold. Going back to the direct cylinder induction thing, maybe a rotary valve could be used to close the crankcase ports and open the cylinder ports. Unleashing the resonance beast? Thanks for the reply and awesome entertainment.
Pin the ring grove to be in the ring gap; so the piston ring won't rotate. A cocked connecting rod may cause the piston to twist back and forth.Use plastigauge to determine connecting rod to crank journal @ different positions.tdc against bdc.
Just a thought but if you put two or three bars in the exhaust port then you can remove them if you think you have too many. Easier than having to add if one is not enough.
If you want to make a slight modification to help during break in period, I don't know if you do this already or not, take the edges of the piston ring and sand them to round them over a slight bit. People replacing pistons on them two stroke bikes do this because there is less chance if they file the edges of it catching on the exhaust or intake.
I think the rings push opposite from the ring gap to the pivot. Hole on the ring changed to long hole or bigger. So it moves freely and won't feel stress. Hope you will be back soon. Love 2stroke.
Pretty sure the piston seal is breaking from ring flex (rapid compression and tension on either side of the pin hole) rather than getting caught on the exhaust port. Changing the ring to be held in using a bulb/T shape or going back to using a lip would probably fix this. 100% agree on not putting all eggs in one basket and putting more focus on results for more easily solved problems while working on new approaches for the more difficult stuff.
LA sleeve co in California will make you whatever sleeve you want, at least they used to, even aluminum or Mag. It’s been probably 15 years since I’ve done that stuff but they were great to work with
Please consider making your bridge as a symmetrical airfoil shape. The leading edge will face the inside of the cylinder. The flat area will be thinner and the aerodynamic drag will be much less. It may wear faster, but that is not a problem for this application.
How are you going to lubricate the exhaust bridge? Many two strokes I have seized because the exhaust side of the piston was not drilled below the ring land.
Narrow rings are better than wide rings, they conform to small changes in the bore shape as the engine heats up, and as it wears. So put TWO NARROW RINGS IN THE SAME RING GROOVE but put their gaps 180 degrees apart. You probably wouldn't need to gap them, just make sure the gap is large enough to prevent ring bind. Back in the day (1980's) I tried it on a BSA bantam engine and I was amazed at the difference, there was a lot less 'ring a ding' less noise and less smoke using the same pre-mix ratio. It was just bolted on the bench with no dyno so I can't give you performance figures. I first wanted a spiral ring, I asked a machine shop to cut me one from a cast iron cylinder liner, imagine cutting a spiral groove. They kept braking then we realised the same idea (no ring gap needed) could be had with much less trouble. Just saying..
While I think focusing on other things is a good idea, I believe the 100% of bore exhaust port might work if you used thicker rings and multiple pins. I don't know if it makes sense but i think that with only 1 pin you create a weak point that would be less affected if you had more pins sharing the load. Anyway, keep going, this project is very interesting!
If you don't fail you can't learn. A real man carry's on and that's exactly what you are doing. I'm completely impressed with your resilience and style! I have an idea for a new style piston ring that can be utilized on your current pistons. How can I get in touch with you?
Is there a way you could add a blend radius to the upper and lower edges of the exhaust port, at least around the area of the retaining pin to stop the ring catching? I still believe this concept can work with some very minor alterations
👍 Absolutely, and they should have been there(was in my design, but forgot to specify before plating...) This is not dead, I'm continuing development in a "normal" engine to focus on only the 100% port.
“For Aluminum Sleeve use 4032 then nikasil plating. On the exhaust bridge it must be relieved for heat expandtion . Keep going your ring idea needs room for the movement of the rings natural operating characters” ~Nick Rhine ( 2 stroke research & development Facebook Group)
Could you use a ring that has a pin sticking out that's part of the ring eliminating the weak point. If you started with a thicker ring and had a milled to the thickness spec all but where the old hole new pin is. Then that would set into a sleeve in the piston to keep the pin from wearing on the piston. Just a thought but it would eliminate the hole(weak link) in ring and still give you the desired result of holding the ring in place. Of course then you have to take into account expansion of parts so nothing binds causing breakage.
Loved the video production on this one. The colour and tone were engaging & the blues music was sheer perfection. The costuming department did a great job with your plaid shirt as it really looked great with the overall colour temperature of the video. Your past life: -child care worker- Hollywood cinematographer!
Is there sufficient room in the hole in the ring to allow for thermal expansion? It might be possible that the failure mode has more to do with the ring expanding out into the exhaust port.
Yeah. I was thinking about thermal expansion, but in a more general fashion, too. I mean: it runs fine for a few seconds and the problem seems to arise as heat builds up. The hole for the pin also creates an obvious weak spot in the ring, exactly where it broke - and exactly the critical area responsible for holding the ring in, is the thinnest/weakest part. Maybe just make a larger "loop" with more material, that extends more towards the middle of the piston? There could also be a harmonic thing going on, where certain RPM:s vibrate the ring in and out very hard, which could fatigue the inside part of the hole.
are you sure its not simply to much material at the weak point on the ring? if you file it down just a little bit maybe it contacts the pistons groove before that weak points.
As an old British 50cc and 125cc motorcycle road racer from the 1960s, I really appreciate your videos. I raced in an interesting era when the 4-stroke engine had to give way to the 2-stroke’s superior horsepower. Although compared to the 4-stroke, 2-strokes were tricky to ride with their extremely narrow power band. This necessitated 50cc bikes having 12 and even 14 speed gearboxes, and a usable rev range of around just 350 revs. So it kept you pretty busy! I’m a retired British engineer, ironically living in Oslo! I’m now in my late 70’s, but still very much a 2-stroke fan. Keep up the good work. It would be fun to meet you sometime, lykke til, Michael Leary
He did a 4 cylinder video?
you sir are amazing
@@tirijalito thank you 😊
oslo is not far from me, you raced here in norway?
Allahumma shalli 'alaa sayyidinaa muhammad wa'alaa aali sayyidinaa muhammad wasallim tasliima😁😊
Yok Tobat Kawan Dan Jangan Lupa Sholat Dan Sholawat😊😁😊😊😊😊
A wise man one said, “Easy isn’t worth anything”.
Your an inspiration Alex!
Thank you for being you!
I wrote that on my toolbox lid inspired by Alex!
I'm proud to say that I got the shirt, it always helps me kick my rear into gear when I need inspiration
I think he meant to write something about having vision and perseverance which is what I see here..easy is worth alot. Especially when your working alone. To me anyway, I think the message he wrote was to himself stay motivated
gay
Allahumma shalli 'alaa sayyidinaa muhammad wa'alaa aali sayyidinaa muhammad wasallim tasliima😁😊
Yok Tobat Kawan Dan Jangan Lupa Sholat Dan Sholawat😊😁
Love the fact that you crankout videos this much faster theres been like 3 in a weeks time
Suomi mainittu
😁👍
suomi mainittu
perkele
Suomi
as someone who solders alot, i feel your pain, i have a scar on my wrist for like 12/13 years now
Test.. break..learn..repeat... What a great project
i'm envious of your calmness, i'd have nuked my entire garage and gone on a 'Falling Down' style rampage...
Many years of practice...
Most excellent comment, chapeaux
@@2STROKESTUFFING A real Buddhist!
Kicked a hole in the garage door when I couldn't line up the long bolt to put my motorcycle engine in. It wasn't even my garage😌
@@davidbeer My garage hae very very thin plywood doors and I hot angry pecause I fucked up a bolt that holds the head on place. So I threw 23mm wrench thru the plywood door and it hit my liltle brothers elbow who was playing on other side of the door
Yes, don't kill a project by trapping yourself in a corner.
Normal rings,normal double porta ex and he will fly,because the main idea head is primary Reed intake and flat valve full opened intake with injection ad secondari.
He forget that concept and loose time with no sense exshaust port that broke ring in a minute..
@@vnsworkshop9961 A Super high Perf 2 stroke gets by on 1 piston ring.Ask any Japanese engine manufacter.Trev New Zealand (repeat holders of the Americas Cup )
Martin...many have !.If he sticks to a Reed intake & dual long timed Ram tuned Rotary valve that with a shot of No2,That should work for him- needs to build a little dyno 1st.Cheers Trev New Zealand
@@trevinskiking2165 of cours ring,not rings,i write wrong.
My mistake.
All serius performance 2 stroke are single ring.
I too am an old 2 stroke racer from the 60's when we were developing fast bikes from slow street bikes. Very innovating ideas with the captured ring. I ran an exhaust port shaped something like a T. I imagine your exhaust port shape is designed that way for scavenging purposes. Also ran a dykes ring. Too much friction??? Seems a larger ring would be easier to hold with your captured ring system. Also we had a graduated chamfer on the top of the exhaust port that eased the ring in a little less abruptly. Love this two stroke stuff! Thanks.
Realy like your content dude, its like a childs paradise here, its so inspiring on my own projects. Keep it up!
Just when we think these videos can't get any better, you do it anyway. Fantastic work.
Just remember if you put a bridge in the exhaust port you need to drill holes in the piston for lubrication and cooling. Otherwise the bridge will heat up more than it should and it will snag the piston.
i had completely forgot about this. good catch
make the bridge deeper so that you can guide cooling water thru a channel in it??
@@DerStoeppel Not worth it
Note:. Bridge in exh should be hand- relieved back from bore by approx .004".
Been doing this on kart open motors and controlled motors for decades. Works great!
Zero issues. Oil holes in piston will be Much Less necessary!!
* Best exh port is 3 port. Large " oval" with "well designed" side ports.
Keep champhering to a minimum.
Port opening must be incredibly parallel to ring!!!!!!
CRG MAXTER 50mm bore on last motors developed, were fantastic, durable.
Piston skirt needs to not impede feed into side fransfers.
Etc
Etc
Etc
Keep up the good work!
@@DerStoeppel could be higly effective but challenging to execute.
You're a legend roughly 2000 dollars for a single cylinder that you designed thats amazing you've put so many hours into research and development I look up to that
i am from the smokey mountians in north georgia usa you have great taste in music .keep up the great work thanx from round
Howdy neighbor
Hey neighbors
Im from the great smokey mountains of northeast Tennessee and i agree
Music is amazing. Any idea who’s playing it?
Who performs this music?
One can really see the even faster progress you make while working in your garage halftime 😊👍🏼
It's really made a difference!
@@2STROKESTUFFING Right! And also the video editing and even your humor is more recognizeable than before! 😊👍🏼
Your choice of blues music is superb
No mention of who it is, Shazam says its Ma Lady J'ai Le, Blues No7, by Daniel D.
@@twinshock175 thanks man, much appreciated hint!
I'm glad you're shelving the 100% port - we all NEED that thing to sing us it's song.
These videos are the best!
The quality of tour videos has realy skyrocketed and i love it, keep the good work up, greatings sweden
This has all been done before. The numbers for max port width in a ringed engine are well known. At 50cc you might try to eliminate the ring and go ABC although, the piston expansion rate would be tremendous.
Allahumma shalli 'alaa sayyidinaa muhammad wa'alaa aali sayyidinaa muhammad wasallim tasliima😁😊
Yok Tobat Kawan Dan Jangan Lupa Sholat Dan Sholawat😊😁
Try a ring like a total seal design. Make a ring with an inner lip. Then use a ring that catches that lip to hold the ring in place. It has no gap but is smaller diameter so does not contact the cylinder wall. Now no uneven parts on the contact ring. Contact ring should be very light contact. Almost zero tension when cold. Ring and engine expansion when warmed up will provide proper contact. You will need to pump heated coolant through the engine to provide enough ring seal to start.
Just because you're addicted to 2t oil, doesn't make it heroin >_>
Also heroin is a trade mark so the video shoud be taken down hahah
@@mrsnezbit2219 Bayer lost its trademark rights to Heroin under the 1919 Treaty of Versailles following the German defeat in World War I. It is no longer enforceable. I know you were joking but I found that an interesting little fact.
No because cannabis has never killed anyone and is therefore far too dangerous to lubricate threads with......Fffffffffh....
@@xeigen2 I didn't know that! Thank you
@Alfred Wedmore Well if you never try you will never know I guess ;-D
Run a ringless piston and run nitro or alcohol / oil mix keeping piston cool just a thought. . Cylinder has to be tapered smaller at top and wider at bottom for ringless piston set up ../ \ ..
Hi, I needed to leave a idea for you to consider:
You could taper your sleeve and have a tapered hole in your cylinder. Just like a morse cone. This will give you the opportunity to switch sleeves with ease. Clean out carbon from between the sleeve and cylinder, hampering your heat dissipation. Moreover pressing an aluminum sleeve into an aluminum cylinder will not be easy, you run the risk of damaging both parts. Jan Thiel also did this with some cylinders, I do not recall which exactly, but I guess you know his work well ;). I hope you get something out of this suggestion! Good luck!
P.s. This might help with timing your sleeve as well. You can fit it, drill a hole for a pin in the top surface of the cylinder, and fit the sleeve even exactly the same every time.
Downside will be that the sleeve will need to be very precise in order to get the heights of your ports to line up!
Heating the cylinder block and chilling the sleeve will let it fall together without any pressing necessary
Right on Guys for giving suggestions I only know of cast iron solid cast small blocks. I was going to suggest a diff. Composite of ring. I am outa my league a lil. Thumbs up to the producer the engineer and the star of the show.B.t.w Do not bore the hole 2 big possible ROD problem. G.L.
People like you keep the 2-stroke alive, keep up the good work!!!
Yup it's been 3 years.... It would be nice to see you get that thing out on the salt flats this summer
Build yourself a 90%/10% nitromethane/methanol burning hemispherical billet 50cc engine with twin spark plugs, and with a twin screw supercharger, and mechanical fuel injection. I'd learn the secrets from the types of Brad Anderson Engineering, etc, then apply that technology to a 50cc build. This would give you fruition to your goal of having the world's most powerful 50cc engine.
Man i hope you saved all these exact designs via blueprints so one day you can manufacture your own serious 2 strokes✅✅🔥🧡
This is great Alex, I’d forgotten about this project you were working on and it popped up on my TH-cam feed. The last time I seen you on here you were casting the engine. You are doing a great job. I’d love to do something like this.
Try a bigger ring gap. Had similar problems with a Kart engine. After I extend the ring gap the problem was gone.
I know thicker rings aren’t great for power, but I seems like a ring double the thickness with chamfers on both sides would alleviate some problems. The ring/cylinder contact would be about the same while allowing the ring to ramp over unsupported walls.
oh man I love this guy's work
for the 100% bore exhaust design, have you considered a spiral piston ring design(essentially overlaping, all the way round twice)? with tapered ends tapering towards the piston on both ends during the heat expansion the ring simply slides the edge that is on top, and the edge that is on bottom towards each other but they can never meet, and it should require no locating pin(hence the tapered edges, the piston would need a deeper ring groove, and wider rings
I don't quite know how to explain this idea, and I have no drawing skills so hopefully what I've said puts forth the idea correctly, I can't find anyone whos done it before or any designs like it online
essentially a piston ring, but the edges keep going around another turn one under one over
Cant wait to see the supercharged version of this motor.
I've been pondering that idea for 5 years lol bout time i see it done by someone
Closest thing i have seen is Detroit diesel supercharged 2strokes
Wife thinks im dumb for how excited i get when you post new vids.. cant wait to see you on the flats with this engine..
Fantastic Videos, really appreciate your work and it has given me ideas for my projects.
One thing - you may have already thought of this - 100% exhaust can still be achieved by adding the thickness of the bridge to the dimensions of the port width = 50% each side of the bridge.... you could then have two bridges if needed.
exactly!
or, even more....^^
@@DerStoeppel there are those who do & the rest watch it on TH-cam.No offended.Trev New Zealand
@@trevinskiking2165 ??eehm, sure?? and, what has that to do with anything, especially the topic? just asking, because some people comment on vids, some dont, regardless of them doing stuff or not... greetz, Stoeppel from Germany
@@DerStoeppel Just what it says, your not Autocratic too are you ? More intelligence than wot you wrote.Goodbye.Trev New Zealand
I know it has to hurt to lose the full width exhaust port, but you may yet be able to come back to this idea for a visit later. Something in the back of my head is remembering pistons that were plated in a particular fashion that allowed them to be used without rings. Something about expansion and contraction rates the would match the cylinder closely enough that rings were not necessary.
Hey man, love your work. I would suggest making your cylinder sleeve out of cast iron or brass just for experimentation purposes then go with plaited aluminium later. Cheers. 👍
Your problem is that the ring is releasing its spring tension into the custom oversized exhaust port. As the tension on the ring expands into the original port it is contacting the floor of the port. You need to put at least 2 port bridges 1 may not solve the problem and the risk will continue to exist. 2, 5 to 7 mm chamfered bridges in the port will solve the problem of the ring releasing its spring tension into the port. A thicker ring might also help. If you are going to supercharge it you might want to use an "O" ringed head and cylinder design to seal in the extra charge. Also you might consider a thicker rod and a larger piston pin design. A very thick rod will ensure large amounts of charge into the combustion chamber does't cause breakage at high rpm and may allow revs up to 15,000 rpm using 10 lbs or more of boost.
Can't wait for the supercharge and Rotary valves stuff!
Me neither, and I realized there's suitable small roots blowers available which could be used as a start. Working on not having my builds drag out soooo long...
@@2STROKESTUFFING Is there really stuff that small? Please when you eventually try give us more info, wanna try myself one day :D
You can’t super charge a two stroke .
@@tonywright8294 Hold my beer!
Indeed hold the beers 😂
Awesome stuff. I have been waiting for!! Realy appreciate how things are going!!!!
You deserve more sub man
A sensible move to drop the bridgeless port idea, you have chased your tail on that for so long and nothing so far has proved reliable. Keep up the good work, Kia kaha.
No, no, ....thank you, for your tenacity, inventiveness and dedication.... cheers buddy ❤️
Before I watch. Congratulations!
Edit: Thankfully, the words I now live by are written on your wall.
You are an amazing example of resilience. Keep going.
You have a great proof of concept. All of this work is something that you and all involved should be proud of.
Nothing worth doing is easy!
The sneak peak looks a lot like the FST cilinder (Foekema Symmetric two-stroke)
Or Frits Overmars' FOS-cylinder... I've never seen anyone pull off the scavenging with this layout, hoping my brute force supercharger approach will circumvent that issue.
@@2STROKESTUFFING Did not realize that there was a scavenging issue with this design. Can you evolve on that?
@@andli461 I've never heard about anyone getting good power out of the system. Might be cause no one has tried "properly" though. Symmetry is key.
@@2STROKESTUFFING I’m a bit puzzled about that as well...since the first time I saw Frits sketches/prototypes I have really liked the idea. 👍 One thinks someone would have solved it by now. 🤔
@@andli461 It's harder than it seems I think. So many things that can throw the symmetry off. Uneven heat distribution, small imperfections in the transfer ducts, case turbulence etc. Such an elegant design though, and now I'm going to defile i with a supercharger....
There is a way to Turbo charge or even supercharge this engine too. you would need to install a rotary valve in the exhaust port to rotate the same speed as the crank shaft: - thus acting as a valve. open on the down stroke, and close on the up, then use a roteryport timing disk, to open on the up cycle, closed on the down. think youll get it.
Youll need use a tiny turbo charger, and use fuel injection. with dialed in timings compression ratio, maybe lowered port height. (can also use more of the power from down stroke too!). Just a thought but think it would work.
Did you notice the twin exhaust duct cylinder with rotary exhaust valves at the end of the video...?
@@2STROKESTUFFING yep I wondered, you think out the box like myself, well done and keep going. 😊😊
@@2STROKESTUFFING just need a valve in the exhaust to keep boost presure
Sad it didnt work out as planner but your face when it broke for the second time is a verry familiair face😂
Never give up! The exhaust so large was a gamble but you tried, now you will have the optimal solution 👌🏻 .. I await the moment that we will hear the engine spinning fast!🙌
I feel your 'Fuck It'
What are your thoughts on running in two strokes? A myth?
Definitely a myth😁
@@2STROKESTUFFING Why am i not totally convinced lol
if you use a supercharger, does that mean you no longer need the crankcase to do the pumping?? does the fuel+air charge go straight in to the cylinder?
Dude, even a 2 stroke ideling the way it should isn't even running 20% of the time, that kind of tells you what to expect ;)
@@raymondo162 The bottom end still needs lubricating though.
You’re a LEGEND in the Making Buddy…. Good Luck with everything, I truly love watching & learning more about how you’re getting SOOO MUCH HorsePower out of engines Sooo Small. By watching you work on these Small Engines, I’m learning more on how I can get more out of Bigger 4-Stroke Engines which I work on. I’ll see you again, next time 👍
maybe do more than 100%?? something like 200° with one 10-20° bridge in the middle??
Did a lot of work with 2-strokes back in the 90s. Found that super-charging only provides over-scavenging and not much else. Turbochargers, on the other hand, add that essential back pressure to increase cylinder pressure, and power. Good luck Alex. We were running and testing a V-6 twin turbo 2-stroke from Jaguar. It was a blast until Ford bought Jag and canned the project. But heck, the power!!!!!
It's been 6 months since I told you to add a bridge to the exhaust !
@Eddie Hitler Considering the name you have, you can brush your teeth with a toilet brush
@Eddie Hitler Forgive him, Eddie. He obviously hasn’t discovered Google yet. Or IMDB. Or comedy.....
Hot gasses move a lot easier than cold gasses hence 4 stroke exhaust valves are always smaller than the corresponding inlet valve, a bridged exhaust port is not going to hurt the project.
It looks like to me that they heat isn't able to get away from The Ring quick enough and eventually melts the ring
Do you NEED a ring gap? Lots of oil to start it with a "loose" ring. Maybe a glow plug to preheat the cylinder and then swap in a spark plug when she's good and warm? Coolant preheat too maybe?
Surely the locating hole in the piston ring needs to be sufficiently inside the inner circumference of the ring itself so you have the full width of the ring all the way around and eliminate week spots like that as from what I can see the hole intrudes into the width of the ring as it is now. Hope this helps.
Before you add that sleeve, why not try a standard style piston and ring to see if the port will work with a standard piston. You can always go back to the three piece piston later. Would be cheaper and quicker, just a thought. Love your videos!! Good luck..
Thanks for sharing this with us. Have you thought about harmonics breaking the ring? The shockwave coming back into the cylinder. I was wondering why it would break at that point? Twice? Could it be a defect in the hole in the ring? Maybe you can try cutting the small hole with a laser. This is very exciting to watch. I grew up with mopeds in the 1970s. All of my friends had them. I had the fastest. One guy had a quicker one because he had it two speed. But I could take him in a mile run. it could run at 52 miles an hour on flat ground. It would go over 60 down the bridge On the way to the beach. I live on the east side of Jacksonville Florida. 13 miles from Jacksonville Beach. It sounded like a bad ass chainsaw. I had a puch engine with a Jawa cylinder and piston. I made a spacer plate out of brass. I took the pedals off and had a piece of 3/4” all thread with foot pegs on it. Straight bars. Long seat Suzuki tm 75 front end. Tomos rear wheel. 17mm racing carb that faced frontward. It was fast and agile but a itch to push to get gas. I would pass school buses going to school. Everybody was like what the fuck. It wasn’t pretty but it looked cool and one day I came home and my mother had given it away. Along with my two Honda motorcycles. That sucked but my dad gave me a 1964 1/2 Ford Mustang. He told me you can’t screw on a moped. And I can tell you that it’s a pretty tight fit in the backseat of a Mustang.
Your commitment is stellar, there's not many people that can keep motivated to finish a great idea. I guess that's why I keep watching I'm always full of dumb ideas, very few ever get finished.
I agree to thin of material on the ring at the locating pin you should only need a thin maybe .5 mm wide bridge maybe 1mm thick into the exhaust port just enough to hold it in place
Keep working at it man. I think keeping the single bridge is key to keeping all the flow you need. Unfortunately the ring Gap has to stay up against the bridge. Excellent video I'm a two-stroke fan from the '80s.
Worked on a competition RX2 motor in the 80's and it just chewed up apex seals at high rpm.
Made the single port a "bridge-port" resulting in a crazy increase in engine life.
Have no idea what the power loss was because we could not get the single port version to last long enough to get to the dyno.
I hope that set screw won't become an issue. I'd imagine possible bulging of the side of the piston if tightened too much or it getting loose if not tight enough... How does threadlock manage with heat?
Put bridges in the cylinder but make it less than the thickness of the cylinder wall. Maybe a quarter of the wall... just a support for the rings and it won't affect the flow that much if it was thinner than the wall cylinder.
I hope a made sense and i tried my best to explain it.
Cheers
I admire your tenacity!! And humbleness.
Thanks•..•for•..•watching....
For•..•profitable•....•investment•...•and•....•guardians>>>>>>
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Keep plugging away and I will keep watching
Could you cast the sleeve with ports and finish it on a lathe? Not sure if the material properties will be sufficient...
That is not a bad idea!
I love your dedication to this build, I would not have had the patience to get this far... But I do feel like I just watched a movie where the good guy dies in the end.
😁 The good guy will rise again!
@@2STROKESTUFFING excellent, a sequel! Keep up the great work. What about beefing up your fail point on the piston ring?
I would use more than one bridge on the port. Even with the retained ring piston, you need to spread out the load to ensure you don't catch a ring on the edge of the port...even with a good chamfered edge. You will get a lot of ring wear where it contacts the bridge so make the bridge/bridges wider. Good tunes while doing the ring filing :). Huge advantage of going to a case intake is you can eliminate the intake port entirely...which I think you have done already...I still think a rotary valve on the case intake would work better than no valve to keep the flow from reversing.
This Norwegian American loves the project. You also share my taste in music Delta Blues.
Lovely Video, as always!
I absolutely love watching you do 2 stroke things, i am totally sure you will find a way to get the most powerful 2 stroke ever!
I been there. When wide ports failed or resulted in poor ring life I shifted a bridged exhaust. When that also gave me heat transfer issues (being an air cooled engine). I finally landed up with 3 ex ports. One main and two aux.
Not sure if this is what you mean by bridge but what if you were to seperate the exhaust into 2 seperate holes so your still drawing the same amount of air out but the hole isn’t so big and makes it less of a ledge in one place for the piston ring to catch on, just a thought, Im not sure how doable it would be!!
That's exactly what a bridge means👍
Keep rocking brother you will get it, I know it's possible, I built a killer weedeater, still fs 76, it turns 14000 rpm, and after 2 years of me abusing it, still kicking ass 33cc I think😎
I really admire the cleverness of widening the exhaust port (with central crossbar) to gain pressure on the piston during its descent. Of course at low revs the performance would not be optimal, but, I must say, that I have not followed previous videos (for now) and I do not know what comes after ... maybe a throttle valve ...
You put the ring in crisis all the same, especially at high / very high rotation speeds (among other things, it is better to make a classic stop :)).
I would propose a somewhat drastic and evolutionary / revolutionary alternative solution ...
You could take out the exhaust port at gas pressure and just drill a relative smaller round hole with an electronically controlled actuator and valve on the outside (depending on the rotation speed). To it you create a constant +/- intense vacuum (perhaps with a little compressor that you always send to the drain, connected to 'Y'). At this point, the expansion exhaust is not even needed, a straight pipe is enough ... there is no more back pressure and the fresh mixture does not escape.
All the defects of the 2 stroke could be removed and its merits enhanced. know, it could be crazy ... or not ...
I know it probably won’t idle well at any low engine speed and may require some exotic coatings, but have you considered keeping 100% bore exhaust port but making a piston with NO ring like a glow fuel nitro engine?
Absolutely. I've heard it doesn't scale well, but I'm definitely trying it - just not in this engine.
Thanks for the reply 👍
Ok cool & understood; the only reason I recommended it was due to you planning to sleeve those cylinder, which would give you the option to go ringless like a glow engine, and the sleeve be replaceable, if it doesn’t turn out, or became damaged / worn.
Hi. Since you are using resonance, Isn't it possible to completely bypass the crankcase, drawing in the mixture through the sides of the cylinder head. Directly, you might then be able to introduce the mixture at what ever angle suits you without having to turn any corners through the ports. Obviously this would give oiling issues but might bring more efficiency in terms of flow?
👍 Absolutely! Will try something of the sort in the future!
@@2STROKESTUFFING I'm mad on two strokes and absolutely love what you are doing, can't wait to hear it sing at max rpm. Blew my mind, the whole open crankcase resonance thing. The switch from carb to resonance is going to be gold. Going back to the direct cylinder induction thing, maybe a rotary valve could be used to close the crankcase ports and open the cylinder ports. Unleashing the resonance beast? Thanks for the reply and awesome entertainment.
Pin the ring grove to be in the ring gap; so the piston ring won't rotate. A cocked connecting rod may cause the piston to twist back and forth.Use plastigauge to determine connecting rod to crank journal @ different positions.tdc against bdc.
Just a thought but if you put two or three bars in the exhaust port then you can remove them if you think you have too many. Easier than having to add if one is not enough.
If you want to make a slight modification to help during break in period, I don't know if you do this already or not, take the edges of the piston ring and sand them to round them over a slight bit. People replacing pistons on them two stroke bikes do this because there is less chance if they file the edges of it catching on the exhaust or intake.
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For•..•profitable•....•investment•...•and•....•guardians>>>>>>
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I think the rings push opposite from the ring gap to the pivot. Hole on the ring changed to long hole or bigger. So it moves freely and won't feel stress. Hope you will be back soon. Love 2stroke.
Pretty sure the piston seal is breaking from ring flex (rapid compression and tension on either side of the pin hole) rather than getting caught on the exhaust port. Changing the ring to be held in using a bulb/T shape or going back to using a lip would probably fix this.
100% agree on not putting all eggs in one basket and putting more focus on results for more easily solved problems while working on new approaches for the more difficult stuff.
LA sleeve co in California will make you whatever sleeve you want, at least they used to, even aluminum or Mag. It’s been probably 15 years since I’ve done that stuff but they were great to work with
Watching this come together is as cool as the Deathwish truck, the camaraderie is inspiring.
Did you thought about the cooling of the bridge or you think with methanol its not a problem?
Please consider making your bridge as a symmetrical airfoil shape. The leading edge will face the inside of the cylinder. The flat area will be thinner and the aerodynamic drag will be much less. It may wear faster, but that is not a problem for this application.
How are you going to lubricate the exhaust bridge? Many two strokes I have seized because the exhaust side of the piston was not drilled below the ring land.
Narrow rings are better than wide rings, they conform to small changes in the bore shape as the engine heats up, and as it wears. So put TWO NARROW RINGS IN THE SAME RING GROOVE but put their gaps 180 degrees apart. You probably wouldn't need to gap them, just make sure the gap is large enough to prevent ring bind. Back in the day (1980's) I tried it on a BSA bantam engine and I was amazed at the difference, there was a lot less 'ring a ding' less noise and less smoke using the same pre-mix ratio. It was just bolted on the bench with no dyno so I can't give you performance figures. I first wanted a spiral ring, I asked a machine shop to cut me one from a cast iron cylinder liner, imagine cutting a spiral groove. They kept braking then we realised the same idea (no ring gap needed) could be had with much less trouble. Just saying..
Same problem with my fl350r there wasn't a bridge on the exhaust port, huge recall on the 85 honda fl350r had them replace the entire top end
While I think focusing on other things is a good idea, I believe the 100% of bore exhaust port might work
if you used thicker rings and multiple pins. I don't know if it makes sense but i think that with only 1 pin
you create a weak point that would be less affected if you had more pins sharing the load.
Anyway, keep going, this project is very interesting!
If you don't fail you can't learn. A real man carry's on and that's exactly what you are doing. I'm completely impressed with your resilience and style!
I have an idea for a new style piston ring that can be utilized on your current pistons. How can I get in touch with you?
Is there a way you could add a blend radius to the upper and lower edges of the exhaust port, at least around the area of the retaining pin to stop the ring catching?
I still believe this concept can work with some very minor alterations
👍 Absolutely, and they should have been there(was in my design, but forgot to specify before plating...) This is not dead, I'm continuing development in a "normal" engine to focus on only the 100% port.
What stops the exhaust gases from getting into the crankcase via the wrist pin holes once the piston goes down past the wide exhaust post??
“For Aluminum Sleeve use 4032 then nikasil plating. On the exhaust bridge it must be relieved for heat expandtion . Keep going your ring idea needs room for the movement of the rings natural operating characters” ~Nick Rhine ( 2 stroke research & development Facebook Group)
The music really suits and complements the video.
Could you use a ring that has a pin sticking out that's part of the ring eliminating the weak point. If you started with a thicker ring and had a milled to the thickness spec all but where the old hole new pin is. Then that would set into a sleeve in the piston to keep the pin from wearing on the piston. Just a thought but it would eliminate the hole(weak link) in ring and still give you the desired result of holding the ring in place. Of course then you have to take into account expansion of parts so nothing binds causing breakage.
Loved the video production on this one. The colour and tone were engaging & the blues music was sheer perfection. The costuming department did a great job with your plaid shirt as it really looked great with the overall colour temperature of the video. Your past life: -child care worker- Hollywood cinematographer!
Is there sufficient room in the hole in the ring to allow for thermal expansion? It might be possible that the failure mode has more to do with the ring expanding out into the exhaust port.
it's a thought.....................
Yeah. I was thinking about thermal expansion, but in a more general fashion, too. I mean: it runs fine for a few seconds and the problem seems to arise as heat builds up.
The hole for the pin also creates an obvious weak spot in the ring, exactly where it broke - and exactly the critical area responsible for holding the ring in, is the thinnest/weakest part. Maybe just make a larger "loop" with more material, that extends more towards the middle of the piston? There could also be a harmonic thing going on, where certain RPM:s vibrate the ring in and out very hard, which could fatigue the inside part of the hole.
are you sure its not simply to much material at the weak point on the ring? if you file it down just a little bit maybe it contacts the pistons groove before that weak points.