Jac on Nostr: There is some complexity when engine efficiency is being considered. Gasoline engines ...

There is some complexity when engine efficiency is being considered. Gasoline engines suffer from volumetric inefficiency, that is to say that for spark ignition to happen the air and fuel has to be in the correct stoichiometric ratio for the full volume of the cylinder. If a carburetor modification moves the ratio outside of the flammability range the engine won’t run. Diesel engines are the most thermodynamically efficient internal combustion engines in widespread use because they draw in air alone and inject only the fuel required to produce the requested power, no volumetric inefficiency. The Prius uses an Atkinson cycle gasoline engine that increases efficiency by elongating the piston stroke to fully utilize combustion pressure at the cost of power to weight ratio, still an equivalent displacement turbo diesel would be much more efficient.