Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Printing the new cylinder

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Awesome, thanks for sharing!

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I cut the A B C port.

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I cut another b port

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

I cut the last transfer port.

Its starting to look like something.

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

looks great, updates?

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Progress!!

I cut the main exaust port.

If it looks like it very low, that is because it is very low!!

165° and a hell of a lot of blow down time area. Cause it is really wide.

Hopefully a hell of a powerband.

And 120° transfer which is not extrem either. I'll get the aux ports done tomorrow.

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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.

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Looks great!

What is the limiting factor on the size of the mold?

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Final version of the cylinder ready!!

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

Here is a picture of the a and b port shape.

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Hey good luck with this!

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

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?

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Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

Kilian Münscher /

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.

Re: The 2nd most powerful 50cc engine. (Casting a cylinder)

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.

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