In article , MikeM wrote:
A MP gauge is nothing but an absolute pressure gauge. If you
disconnected it from the induction manifold and took it aloft,
it would read the same as a manometer; absolute air pressure
decreases with increasing altitude.

Right. And when you turn the engine off on the ground, it reads
current atmospheric pressure.

When connected to the induction, all it shows is the air pressure
on the downstream side of the throttle plate; it is NOT a direct

Yeah. I forgot the ideal gas law for a moment. I should've thought
it through better before posting the question.

measure of engine power! The tables are just attempting to
explain how ****ty a MP is at measuring engine power...

It may not be linear but it is monotonic. Increase the MP (at a fixed
RPM) and you get increased power.


Morris