I got my supercharger installed and its got the NST 9.5psi pulley but im not able to hit the full 9.5psi with it, I changed out the BPV to a TurboXS Type 25, tried to shim that did nothing, tried to mount it backwards did nothing, now Im fresh out of ideas. I have the gates belt the K0708090 I believe the part number is one, but when I tried to put it on it was a pinch to short so im running the gatorback goodyear, but its not making any squealing noises (aside from what the supercharger normally makes) can anyone else think what it would be?

 

well, what are you hitting, i'm pretty sure they don't actually hit 9.5 psi, i think it is only a 9 psi pulley, and an s/c only hits full boost at redline.

did you change any of your other pulleys? like an underdrive pulley? are you sure your belt isn't slipping or not tight enough?

 

you must mean k070890 sized belt. how are you reading the boost levels? with a boost gauge? if so, how much boost are you reaching then? if you are using a boost gauge, it could be that the gauge is a bit inaccurate or your belt is slipping. if it is slipping, try applying a bit of belt dressing and if the gauge is working fine, and the bpv is doing it's job, the dressing should minimize belt slip.

 

Im pretty sure its not slipping, I assume it would make a real high pitched god aweful squeal (did it 1 time not rev match down shifting), yea this is a redline, no other pulleys car is stock except for axel back other wise. I hit between 7-8psi. Could it be the BPV, it was a used one and at idle it makes a popping noise like its kicking and the boost gauge needle starts bouncing around in vac, would that be a vac leak then?

 

belt slip you dont necessarily need to hear a god awful squealing. also, gatorbacks tend to not be completely true to the size they say they are.

 

Yea, I have a boost gauge too

 

Did you do a boost leak test ? you might have a boost leak, I hit 9.5 psi at redline with the bosch. When the boost rises does it rise steady or jump ?

 

You should hit it. On my dyno, I read 9.6 PSI with the same pulley. The slip wont be audible. Check under your hood for belt shavings and that can help tell if its belt slippage. Might be the gauge, or how your looking at it. If not looking at it dead straight on, it might look close. And its only for a brief 10th of a second you would see it.

 

my trd boost gauge only shows 6psi when it should be at 7. im pretty sure i installed the gauge correctly so i dont know why it's off by 1 psi, but trd says it should be between 6-7. my concern tho is that my belt/pulleys make strange squeaks that i think may be causing the loss in pressure.

 

i dont remember seeing anyone mention this, but have you tried another bpv? What was the bpv you were using before the turboxs one? Was it a bosch110? Try swapping them out and see what boost levels your hitting with another bpv. If you are hitting the full 9.5psi then its obviously the bpv. If you are hitting only 6-7 like you are now then its obviously belt slippage. Also as everyone was saying, you wont hear the belt slip since its not a tremendous drop in boost. You would hear a squeal if you were only seeing like 2-3 psi. Look for black dusty powder around the pulley area and near the alternator and by the alternator bracket. Let us know the results

 

Where is your boost source coming from ? I had a problem when I first installed the boost gauge after the bpv (coming from the throttle body) then I switched the gauge and bpv so that the gauge was the closest to the throttle body and before the bpv. After I did this I got the right readings. But it could also be the belt slipping.

 

I only have the stock BPV otherwise but it was a brand new one.

After the t fitting, on the return line to the BPV, should it be else were? Would that also explain why the VAC reading jumps the needle around between 20 and 10 but smooths out when you give it a bit of gas? At idle the car sounds like a little compressor filling up, and by that I mean the BPV starts shaking and wacking around into stuff. Ill try and get a video to show what I mean in the next few days here.

 

i T'd my boost gauge exactly halfway through the existing t coming from the throttle and the bpv. should this be somewhere else?

 

VHT will help with slipping belts, I used this when I have a vortech SC on my car. Also heat will cause different boost levels as well. The hotter it is the thiner the air.

 

i have the turboxs bpv and 9.5 pulley, and with my electronic boost gauge it registers right at 9.5 at redline

 

Interesting, whats VHT?

 

i think hes talking about belt dressing.

 

And as far as teh temp goes its about 90-100 degrees here, Would that play a huge factor in it not hitting full boost?

 

its just as hot if not hotter where i am, so i dont think so, u at a high altitude?

 

No, im in georgia so Im pretty low here. Is the belt dressing VHT brand?