BLNLS1/RX7

iTrader: (2)

Switched my 4.0 pulley on my F!-R ProCharger to a 3.85.After a dyno re-tune I took car to the track and was shocked that I had lost 1/2 second in the 1/4 mile.Made 5 more runs and every run was off between 4 tenths and 6 tenths.Cant figure was going on.

Bob@BruteSpeed

iTrader: (16)

Steve, are you seeing black dust on the blower? With the GTO and an F-1R, I'd actually be surprised if you didn't get belt slippage with a 3.85 pulley. Bob

BLNLS1/RX7

iTrader: (2)

That was the very first thing I though of.But the belt is not slipping at all.

Bob@BruteSpeed

iTrader: (16)

I'd look for a boost leak Steve. You can cap the ends of the tubing at the throttle body and at the blower and put a tire valve in one of the caps and give it several psi of air pressure. Plumbing caps work well for this. Some people find pinhole leaks in their intercoolers, it can make a big difference though. A guy down in Mexico City, Mexico had a boost leak, I've have him try one thing and then another, it came down to his LS6 intake had become cracked internally. Bob

Bob@BruteSpeed

iTrader: (16)

One other thing Steve, the air filter can become a huge restriction too. You have to be careful running without a filter to see if it's the problem, but it's been the problem on many cars. Bob

BLNLS1/RX7

iTrader: (2)

Just put a new intercooler in.

BLNLS1/RX7

iTrader: (2)

No room for a filter.

Bob@BruteSpeed

iTrader: (16)

That would be the first place I'd look. Back at the old shop we had V6 Mustang kit that had a hole in the new intercooler. Bob

BLNLS1/RX7

iTrader: (2)

Will check it on Wed. Thanks Bob.

Blown06

iTrader: (32)

How are you verifying that the belt is not slipping?

Can we see a datalog of the boost curve?

BLNLS1/RX7

iTrader: (2)

Have had different ProChargers over the years and I look for any residule black dust or any other signs ( visual ) of the belt slipping.

BLNLS1/RX7

iTrader: (2)

No leaks in the intercooler Bob.I would call ProCharge tech support but am always put on hold waiting for them to pickup.

BLNLS1/RX7

iTrader: (2)

You sure could if I had one.

BLNLS1/RX7

iTrader: (2)

Got back on the dyno on Wed. and might have found the problem. Will take car to the track next week and see.

Bob@BruteSpeed

iTrader: (16)

What did you find Steve? Bob

BLNLS1/RX7

iTrader: (2)

Went up to Leesburg IN. and had Justin dyno and data log my car since Brent is still recovering from his last surgery in June.Made 5 pulls and it appears that maybe the belt is slipping and was losing a couple lbs. of boost.The car was also running very rich.Made some adjustments and now I need to get to the track with it.How is your Vega coming along Bob?

Blown06

iTrader: (32)

Glad you got it figured out. Do you have any dyno graphs, power numbers or screen shots of the boost curve?

After they found the belt issue, what did they do to fix it?

BLNLS1/RX7

iTrader: (2)

BLNLS1/RX7

iTrader: (2)

Here is dyno graph.

BLNLS1/RX7

iTrader: (2)

17 lb. of boost.