Been a while since my car has run but as I recall with my slightly warmed over stock motor, (cam,ported heads,exhaust,siamesed runners, ported plenum) using the 12lb pulley I can't remember ever seeing over 8 or 9 psi. I remember calling ATI when I first got my boost gauge, and yes I was annoyed after spending $4500 on one of the first vette kits made that it didn't have a boost gauge, they said it was because my engine was modified and the reduced back pressure wouldn't let it hit full boost. Sounded like a easy tech support answer to get people off the phone but at the time, which was around 7 years ago I didn't know any better. New motor is in but not running atm so not sure what it will do boost wise now.
I've been running 10lbs for 2 years on stock engine and boost gauge reads 8 lbs. Going to build lower end and what to raise boost higher. Talked to a tuner last year that claimed to run 15 lbs. Not sure how he did this. Lost his number.
I went from a 4.0 pulley to a 3.6 on a L98. It increased boost from 5-6 to 9 lbs. but my engine was old enough that it could not take that much boost. ATI told me that any more boost on a stock L98 would do damage.
I pulled up some old details of a combo I ran back on a 11.4:1 SCR 350 ci with a large cam, 215cc intake runner heads, ported SR intake, and a 58MM TB. I ran the 2.8 pulley and got like 5.5 psi. Stepped up to the 2.55" blower pulley and got 8.5 psi at 5600 RPM (car made just over 550 RWHP). Just before I changed out the motor and went to a D-1 and a built motor, I pulled the 5700 chip from the MSD and installed a 6200 chip. Ran the motor to redline through the gears (kinda forced it) and found 11 psi.
According to ATI (which if you believe them ...), a 350 stock motor with the 2.55" pulley will make ~22 psi. Yeah right, but it was an interesting point of comparison. Prior to the blower, the car ran 11.9 with a 1.5 60'. Best time with the P-600B was 11.1 @ 128 on slicks.
I did not trade out the P-600B because it broke, I just wanted to do something different with the combo. The D-1 only lasted a short time and then switched to the R version and the other car runs the D-2R. Be careful of getting addicted to this stuff.
Corvette Store
max lbs. boost on p600b?
