I have this writeup in "the canard zone", but my Rutan model 54 has 40 hours on it now with the kohler ch25. Once you disassemble the engine you'll see that it has GM small block written all over it, and in fact uses identical lifters.
Midwest Super Cub has adjustable main jet, plastic intake manifold, and some other developments for it. I cryo'd my whole engine, and the EdSterba prop is outstanding. Gets 110 nautical miles per gallon at VY, and 76 NMPG at 101 KIAS. Vibrates 'way less than the onan. I'd like to get the word out about this engine so folks can get the fleet flying.
-Mechanic X (due to kohler lawyers)
Congratulations. I suggested small industrial v-twin engines about 13 years ago on this forum, glad to see someone is using them. With 40 hours now flown it seems they're more reliable than the Onanism of yore.