|
Forced induction allows the use of a smaller displacement engine, which under non boosted situations would allow higher BSFC operation because the normal loads would be higher than the normal loads on a larger displacement engine.
When you use taller gearing you get better mileage for much the same reason, lower rpm and higher load, even if the displacement is the same.
Ford is doing that with their ecoboost engines, so it has become mainstream.
Better transmission gearing and more speeds in the newest cars as well as dual clutch automatics get better mileage, but in reality the new 6 speed dual clutch transmissions are not automatics, but automated manuals.
If you supercharge and engine you can get more air and fuel into the combustion chamber. That will only give you better mileage if you use fewer total engine revolutions per mile to travel, since if the supercharger will use more fuel per revolution if you use any boost.
regards
Mech
|