Superformance Exhaust

[greg schroeder]

I started with the Roush 427R single plane intake Victor Jr. that comes on a higher HP version of the motor. The Roush bench test with Holley 750 double pumper that came on the engine was 562 corrected at the crank with Roush test headers having 2" primaries and open end collector. In the car it had the Superformance headers with 1 7/8 primaries which are pinched by width at the top to about 1.1 inches give or take to cover about 1/3 inch width of each exhaust port on the AFR 205 heads on the engine. I had the Superformance side pipes too. That set up was just a touch over 400 corrected wheel HP and would trap about 125 mph at the drag strip given about 1000 ft air. I asked the Superformance dealer what's up with the loss of 160 HP. They said that's pretty good, most are only 370 to 390 at the wheels for that motor in the same set up. This makes sense given the motor is supose to only make 550 crank HP and I had 562 crank HP.

I first changed the headers. Here are the before and after.


I also changed to, Pro-System mechanical secondary carb of a bit over 1000 cfm, larger surface area air filter, Aeromotive fuel filter, 1/2 inch or 8AN fuel line from tank pick up to carb and side pipes from Buckshot Racefab with 3 inch louvered cores. This set up made 475 wheel HP The car with this set up made about what the engine should in my opinion and put the car easily into the 10s a little over 130 mph.

I also changed to light weight flywheel, stronger clutch, stronger half shafts and motor mounts with less movement so the pipes don't move and destroy fiberglass were they exit the engine bay.

Lots of pics in my gallery. I had a blast with this car before I sold it. If I did another one I'd do about the same stuff because I went through many of the lessons already.

Click on the link just below to watch and hear the set up at the drags.