Need Help...

[XxJamesAxX]

Hey guys need some help. Its actually for my uncle but anyways I'll try to explain and answer any questions the best that I can. Thanks for any help in advance.

Ok he just bought a LT1 car. I know this is a LS1 site but bare with me.

Car is 93 Camaro Z28 6 speed car. He bought the car from a guy that bought the car from a guy that built the car kinda thing. Car is basically stock with a small/mild cam, headers, exhaust, and a Vortech V1 supercharger with 6lb. pulley.

Ok now to the problem. Going down the road the car runs smooth but lets say you pull out somewhere get to about 10mph in 1st and floor it, the car launches and pulls hard (hard for a stock/mild car) all the way to about 4200-4500RPM then it just quits pulling. Doesn't cut out, doesn't spit and sputter just seems to not want to rev any higher. You can shift to second and it pulls hard to 4500rpm again. Or you can hold it to the floor and it will slowly pull past the 4500 on to 5000-5200rpm or so but revs way to slow.

Sitting in the drive way reving it seems to do better. Reving it to 5500 aint no problem. Still think its not reving quite like it should on top but alot better then when your going down the road. All my experiences in the past tells me that where this car quits pulling is when it should really start to pull its hardest? The car starts right up, idles great, drives down the road smooth. Its just went you get into the throttle hard and it hits 4200-4500rpm it quits pulling.

The car has a aftermarket fuel pump, and suppose to have larger injectors. We thought it may not be getting enough fuel. Tomorrow where taking it to a friend that has a fuel pressure gauge to get that checked.

The boost guage shows about 18-20 vacuum when its idling and 6lbs when you floor it.

If anyone has any suggestions/info anything would be very much appreciated. Thanks in advance and if any more info is need I'll do my best to answer. Thanks

[Jeepplr]

I have a 2500HD 6.0 supercharged that did the same thing. I did am EFI Live tune with Black Bear Performance that determined I was running lean at higher RPM. Could be low fuel pressure or in my case the injectors were too small, I changed to 8.1 injectors now my truck pulls strong all the way through the RPM range.