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Old 07-22-2011, 01:34 PM   #19
AaronGTR
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AKA: Aaron
Join Date: Aug 2002
Location: Detroit area, MI
Age: 39
Posts: 12,197
Vehicle: 2000 Grand Am GT1 2dr
AaronGTR has made plenty of valid pointsAaronGTR has made plenty of valid points
Yep, 2.4" pulley got me 9.5psi at 6300rpm and that equals just over 14,700 blower rpm. The efficiency charts from Eaton only go up to 16,000rpm so I have to assume that is the recommend max blower rpm. I do know the faster you spin them the faster they wear and the more heat they make and efficiency is lost.

A 2.2" pulley would put me just over 16k at my redline. If I backed the redline down to 6100rpm that would keep me under, and allow me to build more boost at lower rpm. A rebuild with new bearings would help but they will still wear faster at that speed. A case porting and coating on the rotors and bores would lower the temps and increase the efficiency a bit. The outlet temps really are the main concern at that boost level though. That's why I've always said this blower is a bit small for this engine. An M90 would be able to make 10psi of boost at a lower rotor speed which would mean lower outlet temps at the same boost level. It's hard to completely get rid of KR at this point without running E85, even on 93 octane. It just needs higher octane and lower temps, so I will probably be adding a water/meth injection kit to it eventually since that will address both, as well as allowing me to set a slightly less rich commanded AFR in PE (since the alcohol is added fuel). Not sure if I will try the 2.2" pulley or not. I'd like the bearings to last for a while.
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Last edited by AaronGTR; 07-22-2011 at 01:37 PM.
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