2.93 upper, 2# lower, only 10 PSI......

[Cos]

As the title says. I have a 2.93 upper, a 2# lower, a MAF.ia, K&N Filter, and a tune. All installed and runs nice.

I just put my overlay on and calibrated it using a compressor and gauge. Works great. I took it out for a spin and I cant get it to go over 10psi. I was expecting 14 or 15. I have tried different RPMs and load. Only thing I can think of is:

- Is there some sort of bypass the last person forgot to disable?
- Is the fuel stabilizer I used holding the boost back?
- Did I calibrate the gauge wrong (doubtful)


Edit:
Just got a response on another forum:

3500 feet elevation.

Someone at sea level may get that boost spinning the SC that fast with those pullies, but you won't.

Ideas? Agree?

 

[MoKo_03SVT]

you should definitely be seeing more than 10lbs of boost with that combo. i am making 13 - 14lbs with just a 2.8 upper.

not sure what would be causing it though. one thing that i CAN tell you for sure, is the fuel stabilizer that you used, has nothing to do with how much boost the s/c is making.

 

[cobracide]

T off the boost line behind the glove box. Run a calibrated gauge.

 

[timspony]

Have you tried using a mechanical boost gauge?? ....sounds like your calibration may be off!?

Do you have an Aux. pulley? ...I can't see having that much belt slippage though!

With a 2.93" upper & stock lower I was making around 14psi....GL

 

[Cos]

you should definitely be seeing more than 10lbs of boost with that combo. i am making 13 - 14lbs with just a 2.8 upper.

not sure what would be causing it though. one thing that i CAN tell you for sure, is the fuel stabilizer that you used, has nothing to do with how much boost the s/c is making.

Thanks good to know it should be doing that.

T off the boost line behind the glove box. Run a calibrated gauge.

I disconnected the boost line inside the engine bay, t'd a calibrated gauge and my air compressor from there. Not sure how moving it to the glovebox is going to make a difference.

Have you tried using a mechanical boost gauge?? ....sounds like your calibration may be off!?

Do you have an Aux. pulley? ...I can't see having that much belt slippage though!

With a 2.93" upper & stock lower I was making around 14psi....GL

It may be off I may have to go through it again. People were saying that my numbers sound low for what I have. On a Mustang Dyno I ran 425 with my setup. Works out to somewhere in the 500 range at the motor. So when I had a boost number come in low it didnt really surprise me. I dont have the boost reading from off the dyno for some reason. I was almost thinking about doing a datalog today to see if the ECU can pick it up.

I have all stock pulleys and a smaller belt. No slipping at all I get the right amount of lash out of it. Idler is in the correct position and never heard any noises or had anything out of the ordinary.

 

[Cos]

Originally posted by Toma
They make 7 psi here stock , maybe 8 on a good day.

With a pulley, maybe 11-12

From my tuner here in Calgary.

 

[rudycobra]

I had same pulley setup and had 15 pounds boost and made 444/484

 

[Cos]

I had same pulley setup and had 15 pounds boost and made 444/484

Right but you are at sea level. I am at the Denver elevation of 3600 ft asl. So my SC spins the same speed but had a lot less air to grab. It makes sense actually.

Not sure about the reality of 2/3 loss psi for my elevation is right but I am starting to believe I am close. Any members from Denver here?