Hi,

I think one needs to define what is expected from the engine. Once that is defined, you can select "the best engine" for that application.

Do you want:
Most reliable?
Most power?
Highest RPM?
Easiest to maintain?
Best availability of parts (most common)?
Best cost for performance ratio?
Most Power to weight?
etc.

Once the above is defined, I think the answer will be more relevant to what you want. Can you tell us what you are looking for?

Fly4Fun,

Wayne