(Cory wrote)
Your requirements are pretty much mutually exclusive. Perhaps the
SMA diesel, although I think it's only 250 hp... You also need to qualify
"certified" for what?

I'll certify you a small-block Chevy 300hp if you want. Anybody
got a pen?

Talking with SMA at Oshkosh, found out their "diesels" are currently only
certified for Jet-A.

Thielert can run regular diesel fuel in their 135 HP 1.7 liter model - don't
know where they are with a 300 hp engine.

--
Montblack