Car is a 97 camaro

355ci all forged running 9.1:1 CR
Heads are heavily ported. flow 275 I and 211 E at .600 lift
Intake is ported
58mm TB
Cam is a 214/224 .567/.606 on a 114
Long tube headers, shrait through exhuast


ATI P1-SC with twin high flows
Im not sure on the pully size
Is the crank one 8''? i used a tape meassure and got that and rember reading that

And i have a 4.25 '' blower pully and i cant figgure out what the size is on the one on the blower now. i tried using mirrors, but simply cant read it. i think its a 3.5???(sound right, like a size they make???)... I also use a tap measure and got 4'' top to bottm. (tape meassure on the 4.25 pully said about 4.6 inches some o guessing there a lil interpulation required.

any way, 8''/3.5' x 4.10 *6000 rpm = '56228 rpm
........................................6500 rpm = 60914 rpm

ATI rates it to 62000 rpm


I have taken the car to only to 6000 rpm and the max boost i have seen is about 8 psi
It will actully hit 8psi about 5200 rpm and just stay there really steady(no waivering)

Why am i not seeing more boost?

And there a spin to the story.....
check out this post from the guy i bought it from.
Here
Same problem?? it spins freely...leak like normal, but i dunno, just wierd


HELP

 

heeey. first to reply to my own post...


just a couple more thoughts, i have checked and re checked the system and it seems good and sealed. the bypass valve is closing all the way im pretty sure.
I was thinking maybe hook up my aircomprssor the then piping and srpay air in there and seeing if i could get some decnet psi with the car shut off. dunno

 

How much do you think you should be seeing? On my 355 w/ stock untouched heads im seeing about 11 psi and thats w/ a 6.66 blower and 2.75 crank through a t-trim. W/ "heavily" Ported Heads, I think that sounds about right.
Scott

 

well i realize i will lose some boost by the added effeicency of the motor, but only 1 or 2 # at most i thought.
I always thought people were running 12-15# at max RPM

maybe i was mislead

 

If the heads/cam setup is causing you to loose some boost, I still dont believe it should be that much. Your boost should climb steadily all the way up to redline. If you can notice the climb slowing or 'flattening' out then thats a sign of a leak/slippage/blockage.

 

First the way you are measuring the pully sizes is wrong. The easiest and most accurate way to measure pulley size is by using a piece of string a wrapping it aroung the pulley. The measurement should give you the circumference of a circle. From that you can calculate the diameter. Your crank pulley should be approximately 7.625. I am not sure about you blower pulley though since ATI sells different sizes.

I would be careful not to overspin that P1SC since you do not want to overspin the blower. This will cause the impeller to crash into the housing. I would also pull the intercooler pipe and make sure that the head unit is not leaking blower oil. P1SC are extremely prone to leaky seals.

When I ran a 15lb pulley on my P600b I saw 11lbs of boost with shorty headers and 10lbs with Hooker longtubes on a built 383.