Engines > Your Own Design
Building a twin cylinder inline i.c. engine
Brian Rupnow:
Yes, Jason, I will do that. The original had a 22 mm bore and a 20mm stroke. I will upgrade that to 25.4mm bore and 22 mm stroke.
Brian Rupnow:
Because the outer diameter of the cylinders grew in size, the crankcase has to "grow" a corresponding amount. The crankcase model isn't finished yet, I have to add more pieces and see what interferes and what doesn't. Right now the crankcase is about 10 mm wider and 23 mm longer than the original crankcase design. Tomorrow I will get to add some more pieces and the holes to mount them. The trick here is deciding which dimensions change from the original drawings and which ones can remain the same.
Jasonb:
Well already you are deviating from a working design and missing points that may be what made it work.
The liner on Malcoms original sits proud of the jacket/fins and presents a small area for the head to seal against which is quite common practice on small IC engines. Yours will need a wide gasket and could be a source of leaks and therefore compression loss.
You also have the 5 hole pattern the wrong way round.
I've altered my scale factor to 0.046" to 1mm as I was thinking the engine was 20mm bore
Brian Rupnow:
Jason--that "no head gasket" thing has never worked for me. I will be modifying the top of the cylinder to take a 1/16" diameter Viton o-ring in a groove 0.030" deep. That works. I will look at the five hole pattern today when I do the cylinder heads.
Vixen:
--- Quote from: Brian Rupnow on January 06, 2024, 07:50:19 PM ---...............snip ................
This past year has been a very challenging one for me, and I have three engines designed and built that either didn't run well or didn't run at all. This has shaken my faith in myself, so I'm going back to an engine design that has proven itself to work well. I am just in the very beginning stages of this engine, so if you are interested, stick around. ---Brian
--- End quote ---
Brian,
Good luck with all the changes you are proposing to make to "an engine design that has proven itself to work well".
Mike
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