I have read several articles/posts re cooling gas engines and I am especially impressed with the work Pe Rivers has done and posted on his site. With that as background, I am curious about how most of you get adequate/proper air cooling to your inverted-mounted 50cc engines-especially when it is in an Extra or Edge (or similar non-round cowled plane).

I am familar with the 2 to 1 rule for exit to inlet area, yet I've seen some installs that cut away just enough of the cowl to clear the head and muffler and they seem to be OK. On most Extra/Edge/Giles cowls, there is a fair amount of the front of the cylinder-head exposed to intake air. Is that enough? Or do they need to follow the 2 to 1 rule too?

I am presently working a cowl mod to my Extra to add a small air dam just aft of the DL50 cylinder to help pull air through the cowl to exit aft of the air dam.

What about baffeling inside the cowl to direct air flow around the cooling fins? I am thinking about putting something just inside the front cowl inlets that would force the air down. Is additional baffeling around the head needed too? Is this overkill??

My goal is adequate cooling to give me reasonably good engine life, but I don't want to do a lot of unnecessary work and add unnecessary weight.

What solutions have you come up with? I would love to see some pics of your installations.