Gears & Axles - Parasitic losses under load only, I'm tired.

The car is a a H/C ls1 making about 425/415. On spray it makes over 552hp. Anyway, It looses power on the street only and feels as if something is holding it back. I know it's not the motor or tune because this is actually the second setup and I've been through over four good tuners. I have subframes which I've always felt weren't installed right because the lift had a slight lean when the guy welded them on.
Also, I have the following. non of which have seemed to fix the problem.
poly tranny mount
bmr torque arm
bmr lca's
tokico rear shocks.
ls7 clutch installed twice.
built m6.
The rear seems to shift also, so I'm buying a panhard bar.
I don't know what else to buy. the car only traps 110 and 117 which i could do 108 before the extra 100 horses.
Almost all the local shops just scratch their head. :bang:

Might be too much for that clutch. What tires, and so forth?

The tires are stock 17's goodyeear gsd3's. Rear is 10 bolt with 3.90's. I just spoke with Bob, formerly of EPS. He didn't think it was the rear. I called the tranny guys. They said the tranny is unlikely.
Only other symptoms is a lateral shift in the rear with cornering....probably need to upgrade panhard.
The clutch doesn't slip on the dyno. and the RPM'S are raising slowly not quickly. It's as if I'm towing a load.

Does the brake pedal feel spongy or have a long travel?

brakes feel ok. new hawk brake pads on the front.

The tires are stock 17's goodyeear gsd3's. Rear is 10 bolt with 3.90's.



May sound dumb, but are you spinnig the tires at the track and o the street. If your tune is good, it is showing good power, no mechanical issues, then traction is the last piece.

brakes feel ok. new hawk brake pads on the front.

My thinking was a rear axle retaining clip could be worn or broken causing the axle to walk and stay in contact with either the inner or outter brake pad and create a constant drag. Could also explain the "rear shift" issue you have been experiencing.

But, if that were the case I would think you would have some sort of brake issue.