- At GA speeds, piston engines are much more fuel efficient.
- But AVGAS is much more expensive than AVTUR
- As a result, you roughly break even on fuel costs per hour and on payload (the engine becomes lighter, but the amount of fuel you have to carry becomes greater).
Er, why does a piston have to burn benzine? A Wankel needs benzine (because of the geometry and compression ratio, diesel cycle does not work with Wankel engine), but what is wrong about a piston diesel engine?