ORIGINAL: franchi
An expert engine builder who made both glow and Diesel engines claimed the a Diesel will produce as much power as a glow engine on 10% fuel.
He must be comparing the glow engine under the same conditions as the diesel, try running a dedicated glow at the rpm that suits it against a dedicated diesel.
And then look at tuned pipes.
Sorry to be harsh here but I find the above quote very disposable and I like diesels.