8/3.33 combo

**GroverDill** · 05-30-2005, 12:20 PM

What kind of boost are we looking at here?

This is going on my 93 with stock lower end.

I currentl have a 6.87/3.1" set up and I see about 9 psi.

Iwould like to keep it at 10 or less.

thanks, I searched but the numbers are too short to search.

**blown1989saleen** · 05-30-2005, 02:42 PM

do a pulley calculation, your gonna be spinning the blower over 49,000RPMs at 6000RPM motor speed, if my calculations are right, at 6000RPM youll be spinning the blower at 49,729 and youll be well over 10psi. what blower? and whats the rest of the combo?

the calculation I use is:

crank pulley dia. DIVIDED by the blower pulley dia. MULTIPLIED by engine speed MULTIPLIED by the blower step up ratio EQUALS your blower speed

**GroverDill** · 05-30-2005, 04:24 PM

I have the spreadsheet that you can put in the pulley sixes and such, just was unsure how impeller speed translates into actual psi.

the rest its
AFR 165's
RPM II
Custom cam (being spec'd by Neil Erikson)
80 Pro M, 70 TB
1 5/8 long tubes
no accesories, elec fan and wp

**blown1989saleen** · 05-30-2005, 04:40 PM

Originally Posted by GroverDill

I have the spreadsheet that you can put in the pulley sixes and such, just was unsure how impeller speed translates into actual psi.

the rest its
AFR 165's
RPM II
Custom cam (being spec'd by Neil Erikson)
80 Pro M, 70 TB
1 5/8 long tubes
no accesories, elec fan and wp

well, there isnt a calculation for boost, as boost is higher with a more restrictive combo and naturally the exact opposite with a higher flowing combo. with the RPMII intake you should flow pretty well but I still see you making around 15psi maybe more in good air ;)

**GroverDill** · 05-30-2005, 04:49 PM

15.

I feel bad for my block.

**86merc** · 05-31-2005, 02:36 PM

If your are worried about too much boost with that pulley combo just short shift the motor around 4500rpm when it hits 10#. HAHAHA

I make 15# in good air with that pulley combo @ 6000rpm. With a safe tune you will be ok.