Picked up a used Procharger kit recently and the guy said it has the 12lb pulley with it. Which pulley determines the amount of boost? I thought it was just the one on the blower, which seems to be 4". The crank pulley seems to be 8". Anyone know what this will net me? I doubt it would be 12psi but i'd like to know what size pulleys for what approx boost. I'm looking to actually get around 7-9psi and want to know pulleys for a tpi with a zz9 cam and a good set of alum heads.

 

Just to give you a idea what my 4" pulley does with mod's in my sig and stock engine.

RPM--PSI
3000-2.5
3500-3.5
4000-4.8
4500-6
5000-8
5500-10
6000-12

 

thanks for the reply. i forgot to mention i have the p1sc kit though. i'm guessing the boost levels are not the same. my bottom end is stock so i definitely need to stay below 9psi and since i have intake/exhaust mods and heads/cam i'm not sure which pulley will give me about that much or less.