I'd like to run my car sans mufflers this year at the track. I know collector length can play an important role in power.

I currently run a dual 3" system with two ultraflo mufflers that I think flow around 1000cfm each, but I'm pretty sure my x-pipe isn't in the best place. It's about 2ft behind the trans crossmember.

What steps should I take or information do I need to make the correct length header extensions?

 

Your best bet would be to buy Larry Meaux's program called "Pipemax". A Google search should get you to his website. I would imagine a collector length of somewhere between 16 and 18 inches. If your header has a "cone" at the 4 pipe merge then that needs to be incorporated into the measurement.

 

I've heard of that program. It gets real good reviews. Seems I need to get to a dyno first though? So I know my rpm where peak hp and tq occur? Ah just another reason to go to the dyno....

I'd like do it when it warms up though, so I can tune the carb. But then I've also heard that what works on the dyno, doesn't work on the track.....

 

If you are running open headers,
take a pair of 18" extentions, paint them with a light color paint, run the car at WOT and where the paint stops burning off is where you cut them off.

After that if you make any major changes, start over to get the length needed.