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Jim2 Jim2 is online now
7.0:1 > 11.3:1
Join Date: Oct 2003
Location: Calgary
Posts: 1,864
Merv, last fall I posted a pressure test showing 1.5 psi differential across my 63mm Carrera TB at 10 psi boost measured in the intake manifold. So in effect I was making 11.5 psi boost prior to the TB in order to get 10 psi in the intake manifold. I believe this loss restriction get exponentially worse as either the flow rate or charge density increases for a given throttlebody restriction (technically called an orifice) and I think you run higher boost than me.

I've only driven my car once since installing my 76mm throttlebody and now I have no measurable loss.

Your change of 3mm equates to 10% more aperature area, this can only be a good!

For interest sake, I recall calculating that my intake charge velocity in my 76mm TB would be 212mph at 1 bar. Bet it's lots higher at 63mm.
Old 04-19-2007, 09:34 AM
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