Supercharger Pulley Size and Boost

[Lextreme II]

Here is what I come up with using Corky Bell's Supercharger Pulley size formula based on the Procharger P1SC & 1UZFE Engine:

Excel Spreadsheet

Have fun......

The first red column is the Pulley Size and this is the supercharger pulley size at a give rpm before over spinning the supercharger. Procharger P1SC impeller speed is 62,000 rpm.

Example #1:
if you want to run 20 psi at 6,200 redline then you should not get pulley smaller then 2.08".

Example #2:
If your supercharger pulley size like 3.0", then you should not rev your engine beyond 9,100 rpm.

Example #3:
If your engine can rev up to 10,000 rpm, then your supercharger pulley should not be smaller then 3.31"

 

[spf_lexus]

wow... if I could only take my present setup another 3,000rpm higher I think a 14psi is as high as i plan... not for any issue but longevity. 7psi engine psi is going to be pretty instantaneous... guessing 3psi by 2500? Thats my guesstimate from using 2x spool rate by 2x top boost and being somewhat humble. Only seeing 3psi by 4000 right now but that has more to do with my current elevation of 5000 feet. I can't even see 7psi at the present moment. Another issue to think about is elevation... if your rocking a 2.08'' pulley and riding the razor's edge then the couple psi strain from the thin air may end up pushing the P1 over it's limits. Of course.... you guy's won;t have to deal with this as much I will. Driving ack and forth 2x a year up 5000, down 5000 lol. That and I will no doubt see horrible traction with my present open diff.

Do you think taking the wheel out of it's efficiency range will even matter? 14psi is the line for efficiency on normal pulley'ed P1sc. obviously the unit will take 20psi but will it "fall off" when you hit 6000? I mean will the 15psi your looking for end up a weaker 15psi from the higher step-up?