19 lbs of boost @ 5000 RPM on a M90? ITS POSSIBLE - Page 5 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

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Old 10-15-2004, 02:19 AM   #41
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It depends on how much pressure you allow. The TB on a Vin C was checked at 444cfm without the screen. The supercharger, however, pulls much much more than that. It pulls enough in to put 8.5 pounds of pressure on the intake. I started wondering how much the engine actually pulls though....

Welp I suck at math but I get the feeling we can figure this out to a fair amount of certainty. I only know the m62 though, but this'll give you an idea.

The crank is 6.875" and the stock pulley is 2.55" So:
6.875 / 2.55 = 2.69
5000rpm * 2.69 = 13,450rpm for the blower
1rotation = (assume) 95% of 62ci = 58.9ci of air
we need cubic feet so 58.9 / 12 = 4.9CF per rotation
4.9cf x 13450 rpm = 65905cfm
65905 / X = Y | Y / 14.7 = 8.5psi(known)
So 8.5 x 14.7 = 124.95 | 65905 / 124.95 = 527cfm

So the engine would need to draw in 527cfm in order to maintain 8.5psi.

NOTE: I get the feeling something is wrong...well at least the last two lines. Someone who'* better than me can maybe pick up/verify?
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Old 10-17-2004, 02:31 AM   #42
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i dont know where you got the last two lines... you need to label them.
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