Moved this thread to the "In theory it could work" section.
I think building your own engines is an interesting topic, but I don't see much applicability to us Locosters. It's hard to find light and physically small engines that are best suited to us. If you can keep the topic towards that direction perhaps it's a plus for us. I don't want this to become a huge useless thread though that doesn't pan out with anything useful, maybe not even educational.
Airplane engines are quite good at what they do. Trying to match them really raises the ante, with the downside of getting yourself hurt when they go wrong.
If you want a light engine remember to keep that in mind and not be distracted by solutions that provide high horsepower for displacement - they may turn out to be different things.
It becomes frustratingly difficult when your goals are different then the general industries, many parts are sort of what you want but not exactly and hard to use the way want to...
it has to be light. otherwise whats the point? i can just get a straight 6 from a truck and slap a turbo on it. but im just going to end up building parts for it anyway.
based on my experience developing an aftermarket cylinder head for volkswagens i realize that there is a big market for modular engine componenets that homebuilders can mix and match. the volkswagen afterparts market is a good example but the prices are just outrageous. and some have dubious engineering. like the racing heads with pathetic cooling fin area and those tiny valve stems. since im both an airplane and car builder i can see that nice sweet spot that covers the needs of both.
it doesnt take much really. there is an ocean of stock parts out there that can be used. its just a few pieces that needs to be made. for an inline 4 it all boils down to crankcase and cylinder heads. and maybe foil air bearings for the turbo.
a flat 6, my main target is harder. there are no diesel flat sixes. and a porsche crank just wont do. so that means a custom crank if i want big journals and thick webs. not much engineering to be done here too. lots of examples around.