4 into 1 exhaust side pipes vs single tube pipe exhaust side pipes

[427PMS]

I have seen a few 427 cars with a single tube pipe exiting the body on passenger and drivers side but mostly what I have seen are 4 into 1 exting the body. Arent most of the single tube pipe exhausts on FIA style cars ? As far a originality or corectness goes would a single tube pipe look ok on a 427 style car ? What if any are the benifts as far as performance is concerned between the 2 types of side pipes. Thanks for the input .

Chris

[strictlypersonl]

The original car had primary pipes designed to maximize power at a certain RPM. If you shorten the distance between the valve and the collector, it (theoretically) will raise the peak torque rpm proportionally. Maybe completely out of any usable range.

But mostly people will notice because it doesn't look right.

[427PMS]

anyone one else want to chime in .

Thanks

[mr0077]

An empirical formula in use in 1966 was L = 120V/N, where L=tuned exhaust length, V=speed of the exhaust pulse (assumed to be 1700 f/s) and N=target RPM for peak power. This works out to a 34" runner length for 6000 RPM.
Bob, do you know what the target RPM for the Cobras was?

FWIW, a Chrysler-developed formula in that same era for tuned intakes was L=72C/N, where L=desired intake length, C=speed of intake pulse (assumed to be 1100 f/s) and N=target RPM for peak power, soooo, for the same 6000 RPM the tuned intake runners would be 13.2".

Your results may vary...

[Snakebit]

Way over my head! Anyone want to discuss the cataclism of the universe? I slept like a baby through that sermon. You can always tell who is an engineer at a party, look for the plastic pocket protector with the 20 pens and pencils sticking out of it!

[mr0077]

Snakebit, you know how to tell the extroverted engineer at the party? He's the guy looking at your shoes instead of his own...

[JAM1775]

If your primary header pipes merge into one large pipe with a flange on the end then bolt to a curved singular pipe to exit the body and flow to a muffler I see no negative consequence. If you use a good merge collector you might even make more power . As far as appearance a nice 3.5-4" pipe turning out at the body maintaing a smooth flow stright thru the balony tip looks pretty nice ! On the FFR forum they did muffler dyno/DB tests. We have an option of 4x4 or a singular "J-Pipe" at the end of the header. If I recall the J-Pipe when fully ported made a bit more power than the 4x4 's. Then again the stock FFR 4x4's collectors have a horrible gap inside where all 4 ports can actually mix / collide. I had mine filled . milled then installed merge collectors with the spike inside to ease the transition from 4x4 to the muffler. For power and better sound I think it is more about velocity and smooth flow control design than the difference between 4x4's and a 4" tube coming right off the header.