Manifold pressure question

[old man emu]

2 hours ago, facthunter said:

A vacuum is  Essentially a place devoid of matter. Hard to achieve but there's no little vacuums and bigger ones

OK. I agree that a true vacuum is a place, be it a bounded by walls, as in a light bulb, or outside the boundaries of astronomical bodies. Your definition is a little bit like being pregnant - you are, or you are not.

[M61A1]

Doesn't anyone have some flying to do?

[facthunter]

OME you can't have fractions or multiples of infinity either. A vacuum is when  there's.... Nothing... Getting back to the measurement of pressure  a bourdon tube is a hollow curved flat sectioned spring and it's straightening is independent of external pressure.  One good thing going for the engine at higher levels is there's less pressure opposing the exit of the exhaust gases. Normally that's included in "Pumping Losses" of an engines  operation but would be a variable back pressure. Nev