Ok, so its been happening since i have had the supercharger in and I'm starting to think it seems a little low. I realize that HFC and other intake mods will decrease the pressure in the intake, but it seems like people with the same mods as me are making about 8-8.5 psi. i log my boost and its always consistently 7.5 psi at redline, so i dont think belt slip is an issue.

here are

Non Rev Up Vortech
3.12 Pulley
MD 3/8" Plenum Spacer (old school one)
Borla Exhaust
Test Pipes

does anyone else with a 3.12 pulley have boost this low?

 

Hmmm . . . I am not as experienced as others are with the Vortech but this does seem somewhat low for having the 3.12 pulley.

 

thats about what im getting.

 

Shouldn't the 3.33 be around 7PSI?

 

I am on the 3.12 with spacer/headers/tespipes and exhaust and I am hitting about 8.5 psi, that seems low.

 

I am at 10.8 psi with the 2.87 pulley and just HKS exhaust. I know that when I go with HFC's, spacer and possibly headers that I will see a drop in my psi but an overall increase in whp. Blackbird, who tuned your car??

 

i tuned it myself using UTEC

 

PSI numbers can change with exhaust mods.

 

Doesn't it also depend on elevation/location?

 

Have you had it on a dyno to log the boost ? If you have and it said 7.5 psi . I would look into belt slip [ which is hard to tell ] and small boost leak some here [ most likely on the plenum ]

 

Indiana isnt Denver ...lol

 

i log the boost after 1/4 runs and pulls in 3rd and 4th gear on the street, so far it seems pretty consistent to 7.5 psi. I wasnt sure if a small leak would produce consistent results like that.

 

Yeah, that's what I was going to suggest too. Sometimes it's easier to detect a leak or belt slippage on a dyno as opposed to driving where you are distracted by . . . well driving. I initially had a little bit of belt slippage when my G was being tuned at GTM and my car wasn't making boost like we thought it would. I don't remember what psi I was at but my whp was in the 350's. Sam determined it was a little bit of belt slippage, fixed the issue and what do you know, 10.7-10.8 psi and 384.1whp on a conservative tune.

 

The belt will slip some no matter how hard you try to keep it from slipping . But it does need to be tighter than most think . A plenum leak sometime can only be detected after a certain psi level is reached and can be only found by pressurizing the system with out the motor running .

 

i have a pressure tester that i had for my old turbo car, but the compressor is so close to the radiator core support i cant slip it in. Ill try tightening the belt more and check for any leaks in the plenum spacer area and report back.

 

The belt needs to be really really tight, if you cant pluck it like a guitar string and get a sound, its not tight enough.

 

so i tightened my belt a little more today and what do you know, 8 psi. I guess it was slipping the whole time. I got the belt to sound like the E string on a guitar. How do you know if you are over tightening the belt?

 

Glad to hear that helped a little bit.

 

Excellent question. Anyone know the answer?

 

I have tighten it till my wrist got tired . I was trying to see how tight I could get it . Didnt seem to bother anything but I wouldnt run it that way to long . Bearings in the pulleys will wear out . I would think .