A supercharger is a forced induction aftermarket upgrade that can be made to many cars' engines to boost the power output of a stock engine. By forcing more air into the engine, it may burn more fuel during each induction/combustion cycle, producing more power and, in effect, more speed. Calculate the power gain your motor would get from a supercharger upgrade with a few simple calculations.
Divide 1psi (as in 1 pound of boost) by the normal atmospheric pressure in your area. At sea level, this is 14.7psi which would give a boost ratio of 0.06802. This is the percentage of boost you can expect to yield from 1psi of boost.
Determine the amount of boost you plan on running the supercharger at. Most superchargers will do fine at 5psi but can reach up to 20psi of boost.
Multiply the anticipated boost level by the boost ratio to find the expected percentage of your horsepower increase. In our example, we will run 10psi of boost, multiplied by the boost ratio, or 0.06802, which would yield a 68% boost in horsepower.
Multiply the pre-supercharged horsepower of your engine by the percentage of anticipated boost to find the approximate number of horsepower expected from the supercharger.
Add the expected horsepower boost to the pre-supercharged horsepower of your engine to find the final expected power output of the engine after a supercharger upgrade.
