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3" to 2 1/2" Pipe

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Old Feb 12, 2011 | 11:07 AM
  #1  
ss4chad's Avatar
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Default 3" to 2 1/2" Pipe

My 02 Camaro is getting a new motor (427) and the factory exhaust as well as MANY other exhuast companies make pipes that feed two headers into one 3" pipe (no cats) or even into an X or H pipe and then split into two pipes.

What is wrong with going from headers to dual 2 1/2" oval tubing all the way to the rear?

Seams to me you would have 5" of exhaust area instead of 3". Is this right or am I missing some other secret exhaust formula that would restrict my new motor's exhaust path?

I lowered the car so I have ground clearence issues. The new Kooks exhaust I seen is what I would like but I would drag those off in less than 100 yards.

But if I went with oval tubing:
3" round tube to 2 1/4" tall x 3 3/8" Wide oval tube
or even reduced it a 1/2" more:
2 1/2" round tube to 1 3/4" tall x 2 13/16" wide oval tube

I would more than solve ground the clearence issue but would I restrict the exhaust path with the smaller tube? I dont think so, what do you think?

Chad
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Old Feb 12, 2011 | 11:34 AM
  #2  
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Look at it like this with the traditional 3" y-pipe every bit of your exhaust gas is traveling through there. If you have 2 1/2" duals you are actually gaining 1" of diameter over the entire engine. If you break down it into each side of the motor one 3" y means an 1 1/2 every 4 cylinders. If you have have 2 1/2 duals you gain an inch of diameter every 4 cylinders. That is 66% gain in flow capacity. This is by no means exact or scientific but its the way I look at it.
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Old Feb 13, 2011 | 08:20 PM
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I run 2.5 exhaust on my heads and cam z06 and it is plenty. I had 3 inch true duals on my old lt1 car and it was overkill, the mufflers never even got too hot to touch.
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