Whose running a VR4 Paxton on a TPI? - Third Generation F-Body Message Boards

SharpZ28 · 02-12-2005, 02:46 PM

I am interested in up- grading my SN2000 on my 92 Z28. It has the basic TPI bolt-ons, SLP runners, Accel intake, ported upper plenum, MSD6Al ignition, Hedman long tubes, and true dual 3'' exhaust with Flowmaster single chamber delta force mufflers. I was wondering who is running the Vr4, and how do you like it? Also my motor is stock internally with only 34k original miles, so would I be flirting with disaster by running the boost this unit can put out? Thanks for any help or in-put.

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IROC_5796 · 03-03-2005, 04:46 PM

http://thirdgen.org/techbb2/showthre...hreadid=280317 if you havent seen it already.

LBSZ28BLOWN · 03-04-2005, 12:07 AM

Yep, I've done the VR4 upgrade on a TPI, It's not as easy as you think.
The VR4 flows alot of air it needs 1500cfm, thats one BIG A$$
filter, you'll need 4inch ducting to the filter, and you will definatly
need a 8 rib belt setup, and thats really not big enough, 10 rib would be better, I still have a Belt slipping issue: (http://www.superchargerhelp.com/showthread.php?t=7190)
I'm only getting 11 to 12 psi before the belt slips.
You'll need a big exhaust, and need to regap your Spark plugs
down to .030 or less or you will just blow out the spark.
and this is the big one: enough fuel and a proper tune,
I found that my combo liked an AFR of 12.7 and a max timing of 23deg.