open exhaust "tailpipes" or long collector extensions

[Dragsinger]

Racers,

As I race into my "mature" years noise is more bothersome to me than in my younger years. In addition, methanol fumes have become troublesome to me.

With the 1987 Buick Regal I have under construction it will have exhaust exits well behind the driver. The engine package is SBC, 413 CI, about 720 horse on Methanol. The Lemon headers are 1 3/4 x 1 7/8 x 3 1/2 collector.

I am considering a design similar to NASCAR where the tailpipes side exit behind the driver. Possibly build with oval tubing to help ground clearance.

Question; what is a guideline to build these tailpipes yet not be a restriction, not cost any power, maybe even enhance power?

[MadBill]

According to the excellent (and inexpensive) PipeMax program from SpeedTalker Larry Meaux, there are several engine and application-specific tailpipe lengths, e.g. 16" and 64" might be best/better/good, but 24 & 48" would be bad. 3.5" sounds just right for the collectors, but 3" is more than enough for the tailpipes.

You didn't actually say it will be muffled, but assuming so, the 'tune' ends at the muffler but the tailpipe length can have hard-to-predict effects on resonance. You might want to dump out the passenger side JIC.

[emsvitil]

Use termination box(es) after the appropriate length of collector.

Any pipe after the box shouldn't have an affect.