4" DP Question

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Oct 25, 2007 | 07:13 PM

Twin76mmTA

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From: in the Pits

4" DP Question

I know the formula to figure out the CFm that can be flowed through a 4" pipe but since i don't know the velocity of the exhaust exiting the turbo i can't figure it out.

So as a rule of thumb how much HP can a 4" DP support?

Oct 26, 2007 | 07:06 AM

smokinHawk

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From: Columbus, ohio

allot

probably around 1400-1500rwhp, maybe more but backpressure will increase

Oct 26, 2007 | 07:39 AM

EspaceF1Fan

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Will you have one or two 4-inch downpipes?
Whats your power goal?
Also, keep in mind alot of 4 banger guys find 4 inch downpipes to add some power even at a lowly 450-500hp(thats the point they see 3inch as a restriction), so maybe a 5 inch is in your future? I'm sure a 4 inch has to support up 700-800-ish atleast.

Oct 26, 2007 | 08:40 AM

RealQuick

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From: MA

Quote:

Originally Posted by EspaceF1Fan

3" has supported 1000rwhp depending on cubic inch.

Oct 26, 2007 | 09:14 AM

jason99frc

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From: GIVING THE SHOCKER IN ORLANDO

In a regular exhaust application a single 4" exhaust is good for 675 FWHP before a restriction in noticed. I would expect the same or a little higher for a Downpipe on a turbo setup so 1300 - 1400 ish should be on target.