Atmospheric pressure

Hello ... what percentage affects the atmospheric pressure in relation to the height, a turbo engine.

to an engine with turbo almost nothing, to the aimless much much,

The atmospheric pressure influences the compression of an engine and in what percentage ..

The compression measure can vary according to the engine RPM, so the compression measurement must be taken at the engine starting speed since the volumetric yield decreases to the highest rpm of the engine since the higher RPM the filling time of the cylinder is lower and the atmospheric pressure enters into play, then it means that at the lowest atmospheric pressure the filling time is smaller Atmospheric
In an engine on fed, the atmospheric pressure is almost not affected, since the filling pressure is much higher than the atmospheric pressure, but if in the height the percentage of oxygen in the air is lower and that affects a stoichiometric mescla

if I measure the compression of an engine at sea level and 4200 meters