Question for the Motor Heads

[Babi]

Originally Posted by SYN_Bliss

Once you see that a loaded engine at 2500 RPMs can use more air and fuel than an unloaded engine at 10,000 RPMs - meaning RPM's are just part of the equation, then you can start to understand the load part of it.

I think we are expressing the same thing with different approaches. To me it's more intuitive to think that the intake pressure is dependant on "throttle" (throttle butterfly valve position) which causes a pressure drop, and engine RPM because it mechanically drives the supercharger (the relation between supercharger's RPM and its compression ratio may depend on the type of sc, not sure though).

A loaded engine at 2000 rpm achieves more boost (and consumes more fuel) than an unloaded one at 2000 rpm just because in the unloaded one the butterfly valve (throttle) is "more closed" (otherwise RPMs would go up) which causes a bigger pressure drop.

the point is that, ignoring the external pressure dependance, the intake pressure should depend on 2 variables, not three.

Do we agree on this?

Regarding the game, at constant altitude and throttle, if the prop pitch is coarsed (load increases, RPM decrease) the intake pressure goes up, which is not what one would think since the supercharger spins slower.