I'm running a Comptech SC with 9 psi pulley, AEM EMS tuned with 550cc injectors. Last ran on a Mustang Dyno made 282 rwhp and 191 trq, with max boost 8.5 psi at 8K rpm. That was back on 6/4.

Today, I went back to get the car fine tune a bit more, and the first few runs on the dyno, the car only made 220 something to the wheels. We checked the boost, and it was only making 5.5 to 6 psi max. (BTW, I dont have a boost gauge, so we were montoring the boost through the laptop) Thought we're leaking boost somewhere and we checked all the connections, screws and bolts.

Let the car cool down a bit, then we ran again. This last time the car made 270 rwhp but the boost was maxing out at 7 psi at 7K, and then it slips down to 6 psi when we get to 8K.

Well, I couldn't think of anything else other than the belt is slipping. Now my question is if there are anything else that I've overlooked? If there are anything else causing the boost drop? Has anyone else encounter this problem before?

Also, are there anywhere that sells a 8 rib pulley for the Comptech SC? Because I think having a 8 rib pulley may help the belt slip, if it is indeed slipping. Well, hope I can get some help here.

 

Did you check the belt tension? Sounds like tightening the belt could be a solution.

 

not yet. but i will go back in a few days to let my tuner check things out more thoroughly. in fact i am suspecting the belt tensioner is causing it, but how tight should that be?

 

From the Comptech install directions:


Check the belt tension by applying 20lbs. of force to the
drive side of the belt (side opposite the tensioner), deflection
should be .500

 

[QUOTE=Slows2k,Jun 20 2005, 06:54 PM] From the Comptech install directions:


Check the belt tension by applying 20lbs. of force to the
drive side of the belt (side opposite the tensioner), deflection
should be .500

 

Dirty air filter. Fouled compressor.

 

I would think it is a 99% chance it is just a stretched belt. As Slows2K suggested, retighten it. Failure to retighten it could lead to premature belt wear and problems.

 

that's what i'm thinking, and i dont think there's anything else causing it.

 

actually had the same problem with my old pulley even after we tighten it. Replaced it with the ASP racing pulley and had no problem ever-since.

 

really? ok.. i may look into that if all else fail.