Paxton, Vortech, and ATI procharger usually have a pulley ratio of around 1.5/2 to 1, plus the step-up ratio inside the blower, around 5 to one. So, at 6000 engine rpm, times 1.5 drive ratio (conservative) and 5 to 1 step up.... your blower would be spinning 45,000 rpm. Really big centrifugals can flow 3000 cfm, plus.
