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Calculating impeller speeds

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Old 08-02-2004, 11:52 AM
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Default Calculating impeller speeds

How would one calculate the impeller speed based in the crank and blower pullies? Do anyone know the diameter of the 'normal' Procharger crank pullie? TIA.
Old 08-02-2004, 12:01 PM
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the stock ATI crank pulley is 5.85" if I remember, crank pulley/blower pulley X 4.1 X engine RPM

P1SC and D1SC are 4.1 step up
Old 08-02-2004, 12:06 PM
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Originally Posted by ls1290
How would one calculate the impeller speed based in the crank and blower pullies? Do anyone know the diameter of the 'normal' Procharger crank pullie? TIA.
Blower Speed = Diameter or Crank pulley/Diameter of blower pulley * Step ratio of blower * Engine Rpm.

Pulley diameters can be determined by taking a piece of string and wrapping it around a pulley (make sure string is in the rib). Measuring the string will give you the circumference of a circle. From that you can calculate the diameter of the pulley.

I know for LT1 cars the blower crank pulley is 7.65 inches.
Old 08-02-2004, 01:34 PM
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What would the affects of running the blower at 86% of its maximum impeller speed compared to 71%? How much would the IAT increase?
Old 08-03-2004, 03:57 PM
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Originally Posted by ls1290
What would the affects of running the blower at 86% of its maximum impeller speed compared to 71%? How much would the IAT increase?
Anyone... No one has changed blower pullie sizes to increased the amount of boost created?
Old 08-03-2004, 04:02 PM
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plenty have changed pullies but I doubt many if any have measured IAT differences between the 2

I can tell you p1sc, non intercooled pullied for 90% of max impeller speed my cruise IAT's would hit 150 on a 90 degree day.
Old 08-03-2004, 06:46 PM
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Right now, with my D-1SC with its 4:1 setup, I'm spinning the blower around 14,000rpms before its max at 6000rpms, thats where I make peak power, and I'm only seeing 11psi I'm running a 7.25" crank pulley and a 3.4" blower

I ordered a 3.2" about a week ago



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