I would think that a purpose built engine
Would do well.

In a perfect world: The 4 stroke engine would be gasoline, high compression, compressed supercharged/turbo, large intake valve ,
With ignition, and bearing in camshaft.


Or scrap the 4 stroke use a two stroke
And use some sort of power valve like the motocross bikes use.


Above all this though, it comes down to ease of use, and amount of time needed for
Maintinence.

Obviously this is the biggest factor that causes one to
Shift from glow to petro.
As we all know, it isn't because gas is lighter or
more powerful. It is because of ease that goes along
With it.