Don't discount auto engines in AC. I have an AC engine in my E Racer, but all the systems feeding the engine are not Lycoming. Twin Electronic egnition, Twin electric fuel pumps, FAST programable electronic fuel injection, vortech supercharger,all automotive, but the engine knows nothing of what is supplying the Fuel ,spark, manifold pressure and timing, and if all systems are correct , it will perform perfectly. Jonh hit it right on the nose, All of these engines will perform very well, it's the systems that manage the engine is what will take time to develope. There has been tremendous progress in the last year or two and I believe the solution to the problems is in the very near future. It took me 5 years of development and perfect my lycoming AC engine to accept these changes in the ing.-fuel-and manifold pressure I was looking for but dedication and persistance did prevail. After all this time, I think I have all my ducks in a row and My AC is flying better than ever before.
E Racer 113