Originally Posted by blownaltered
I believe the formula is. Lower pulley diameter/top pulley= X engine rpm= X step up ratio= blower rpm
The max is written on your blower along with the step up ratio. Engine rpm would be where you shift at or the max rpm you want to run. Hope this helps
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(Crank pulley size
/ Blower pulley size
X step up ratio
) X max rpm
= impeller speed
Bold items are simply to separate the math
So how do you know if you are over spinning a blower? I bought my P1
used and it came with the smaller pulley. The shop said it was fine so I didn't worry about it.
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I'm
assuming a
lot here as I don't have all your specs. So your roughly 630
whp? I'll also assume you've got headers & full exhaust?
P1SC-1's max impeller (max efficiency) speed is 65k. It should also be a 4.1 gear (step-up) ratio. Your blower pulley roughly a 3.60? And crank pulley a 7.5.
So [I](Crank pulley size / Blower pulley size x step up ratio) x max rpm=
61.5k impeller speed @ 7,200rpm. So your around 95% the max efficiency.
To see that kind of power on a P1 I'm guessing the car is around 12-14psi. What kind of psi are you seeing?
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