Printing the new cylinder
Awesome, thanks for sharing!
I bit of a lack of progress on this ptojekt but i now finished the final zylinder desinge. Not 100% of bore just cause i want a working cylinder first and then i can start experimenting.
I also started cuttimg the ports in the linder. I can send pictures in the evening.
And i am usimg better cooling but not as good as in the 100% of bore cylinder.
Now directed wich meens. The water comes in in the back of the cylinder than it flows around it, over the exaust and im the back of the cylinder up again.
looks great, updates?
Sorry for the lack of progress.
It just that school has started and it quit busy so I only get maybe 2 hours of time working on it. No progress so far but working on a maybe better water for for the cooling
Auf ports have been cut!!!
The liner is finished.
Looks really good.
The cylinder i am going to cast is being air cooled as i want to do moped racing with it (maybe) and in Germany there are in most races only air cooled cylinders allowed. But i won't cast the fins as it would need to big of a mold instead i am going to tig weld them on.
What is the limiting factor on the size of the mold?
Well there are 2.
First I can't melt to much aluminium in one batch. And the mold needs to be burned out and the burnouts oven of mine isn't very big.
Hey good luck with this!
Very cool, the ports look somewhat unconventional but perhaps you are on to something.
I'm thinking the angle looks really shallow which normally I would avoid due to short circuiting the charge but perhaps with low blowdown it will be very efficient.
Sorry to butt into this thread with this, especially since I can’t remeber if I asked this question somewhere before.
Google gives me nothing.
For short lived, but possibly crazy good scavenging, would it be possible to put pulse jet style reed valves in the head of the piston?
- It wouldn’t care about transfer timing; the valves would always open and close at optimal pressure differences.
- It would cool the piston and flow oil past the bearings better.
- It would allow 360* exhaust porting. Filling from the center, pushing exhaust out.
I imaging it would be hard to get a good seal (if possible at all) and the lifespan would be very short.
I dont have the equipment to try it. Clearly some of y’all do. I probably could google the combustion chamber temp and pressure of a pulse jet and compare it to 2T engine. Just fishing for an opinion if this idea deserves to be on my “back burner” or scrapped as a wild fantasy.
This pic is of the pulse jet reeds. My idea would invert them so the petals point toward the center. What do you think?
An interesting idea.
I am not too sure how well it would work with a carburetor cause of serious blowback that is also very hot. Basically a bit like the big diesel 2 sttokes with a valve on top. What I think would be way cooler and more powerful but extremely hard to build would be a 2 stroke with a rotary valve onto so like a drum with a hole in it there a some four-stroke using drum rotary valves and a ring of exaust ports down below. And of course a rootsblower for the intake charge.
To get back to the reed valve. I think it could work with a extremly good pipe, but not very efficiently cause of the high vacuum needed to open the reed . So maybe a blower. Also I am extremly surprised that turbos use metal reeds cause I would think that if they get to hot the material gets to soft to be usable.
I guess I should have said in my mind’s eye the intake would still have its own reeds or piston ported.
The piston reeds would only replace the transfer ports function.
I, in my limited imagination of such a thing, think that the intertia of the petals as the piston transitions from down stroke, to full stop, then up stroke would want to hold them shut during the period that they need to flow.
Perhaps V-reeds aimed up would be a better design. I know, without experimenting, that the cost and complication wouldn’t make sense for any normal application. But for “the most powerful 50cc engine” it might be worth a try.
Cool idea not sure if it would work.
The upwordsangle of the transfers is 25° witch is for that kind of scavenging setup even better than straight in. Cause of the better controll over the air column.
Maybe it's worth exploring. I'd be worried about the piston hitting those reed valves if they don't close quick enough. And it could backfire through the transfers if they don't seal.
Most two-stroke diesels have exhaust valves in the head and intake/transfer ports at the bottom of the cylinder.
Are the auxilary ports the same height as the exhaust port?
They are about 0.3mm lower but that is not visible on the Portmap.
When everything goes according to the plan I am going to cast the cylinder today.
The mold is finished (2 parts sand, 2 parts
Plaster of Paris, 1.5 parts water)
The only other thing I am going to need is the crucible that can hold the amount of aluminum in it. It is going to be made of sheet metal.
I hope your have vents somewhere!
I do atm they are not visible because of the plaster but there are vents.
As an apprentice patternmaker, I took a basic cast metals class at my local college and was able to apply a lot of what I learned into actual practice. I quickly learned casting metals is 10% pouring, and 90% preparation/design. Good luck with your project.
The casting failed pretty badly. As it had cracked and all the metal has flowen out on the bottom. Until now that hasn't been a problem but I am thinking about a real burnout oven now as the cracking was caused by the uneven heating of the burner.
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