I'm posting for a friend of mine. He has a ATI P1SC blower installed in his car. He was running water injection before with a 4.25 pulley. He was seeing 8# of boost. We installed an intercooler on his car along with a 3.70 pulley. His boost guage is not reading above 5# now. We checked for leaks and found none. The motor is a 355 with afr heads and lt4 cam. He is running a vortec bypass valve. We tried the 4.25, 4.00, and 3.70 pulley with no change in boost. Any help would be greatly appreciated!

 

welcome to the club...mondo bypass valve?

 

I am the guy with the car.I have the vortech maxflow race bypass valve, not the mondo.Are there valve known to be bad? Also is the tensioner supose to move or do the stay in one spot.

 

I am running 2 evo bypass valves. I had a HKS blow-off valve which had a better poppet type seal, but, I had to modify it to a bypass type to recirc the air. Not installed yet, but, maybe this winter. As for the ATI tensioner, I had a P600B, and, moved to the D1 head. I am running a 7.6 -> 3.4" pulley combo which results in 13 psi running thru a large Spearco IC. I modified the tensioner assembly so that it would not unload the belt in off-throttle decel mode. This mod lowered the cantileaver load on the crank (less dialed in spring load), and, did not allow the tensioner to vibrate with large amplitudes. I think the standard ATI design is flawed (my opinion). My change works much better for me, and, is simple. Hope this helps. (97ss 383 - D1) B.

 

how did you go about checking for leaks, did you make yourself a boost leak checker?

 

Various pressure gage taps @ different locations in the pressure circuit. ie... Press tap @ (compressor and IC inlet) IC outlet, IC outlet after bypass valve, Intake manifold. Multiple press gage(s) is ideal, but, it's alot of hardware.

 

cant you just disconnect the ic pipe from the tb and cap it, then disconnect the ic pipe from the compressor and cap it with a pvc end cap with a scrader valve to pressurize the whole ic system and monitor pressure drop as well as spray the connections with soapy water and look for bubbles, this is just the way i used to do it

 

Thanks for the help but i figured it out.The tensioner needed to be adjusted differently than i did it.