What does a supercharger do to your car?

What does a supercharger do to your car?
It increases the hp/torque of the engine by increasing its(VE)volumetric efficiency. It does this by force air/fuel into theengine under great than atmospheric pressure(boost). Boost isAbsolute pressure(coming out of the supercharger-atmosphericpressure(14.7psi aprox.) Absolute pressure/atmospheric = P/RTheoretically how many times more air the engine is seeing.
An example:
a 302 v8 that normally has a V.E. of 80% = only 241cuin. of theengine is filling per complete cycle. BUT with a superchargerrunning at 7.5PSI (boost) 1.5p/r =361cuin is consuming/ 50% more= apossible 50% increase in power. I say possible/theoretical becausecompressing air heats it, causing a reducing the increased amount.air to intercoolers and alcohol injection can get it close(90%) tothe potential output, only air/water with ice can get at or abovethe estimate. So a 300hp 302 with a 7.5psi intercooled kit shouldget close to 450hp, probably 435hp is more likely, for a 135-150hpincrease.