Originally posted by techinspector1
Look at the blower boost chart, compression ratio down the left side and boost psi across the top. This will tell you how much boost you can run on pump gas and on racing gas.....
http://www.blowerdriveservice.com/techcharts.php
And, as always, your mileage may vary . As mentioned, only use that chart as a guide. Final boost pressure will vary by engine and will depend on what other modifications have been done to increase breathing. Increasing the engine's capability to breath will decrease boost pressure due to decreasing the back pressure built into the engine.

A supercharger sized to a stock SBC with 5 psi boost, may in fact only produce 2 or 3 psi boost after porting the heads with larger valves and increased exhaust breathing, but increase power due to the ability for the engine to breath better.