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      03-06-2010, 07:50 PM   #1
masitr
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Front Section / X-Pipe Exhaust Diameters

I have been trying to find some information on the Aftermarket vs. Stock exhaust system diameters. Needless to say I have not had much luck, mainly on the X-pipe / Front section. Some manufacturers list the rear sections specs and seem to range from 2.5"-3.0".

Any info on the front sections would be appreciated. Also I know some resonators neck down inside. If you noticed this please include.
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      03-06-2010, 08:17 PM   #2
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Should be 2.5" going to 3" will lose major torque.
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      03-06-2010, 08:37 PM   #3
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Quote:
Originally Posted by MrHarris View Post
Should be 2.5" going to 3" will lose major torque.


QUOTED FOR TRUTH

You'd be surprised how many people don't understand this basic principle.

I see some brands that use 3" exhaust piping for the x-pipe section. An exhaust pipe diameter that size (on our car), will lose a lot of low to midrage torque.

Yes, it reduces the back pressure restriction, but unfortunately it also KILLS the velocity of the exhaust gas flow.

2.75" is about the max for exhaust pipe diameter on the S65 engine.

Anything larger than that will kill your exhaust gas flow...and your low end torque will drop off a cliff.
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      03-07-2010, 09:42 PM   #4
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I was wondering if 2.75 was currently used.

Is the loss of toque with larger pipe due to a mismatch between ECU Calibration and part. Obviously most manufactures make products that match the factory calibration (AKA Stock Vehicle) and not for max power after a proper tune. Have manufactures and tuners tried to tune with a larger system that could prove this? With only flashes available engine performance would seemingly be limited.

Last edited by masitr; 03-09-2010 at 06:49 PM.
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      03-09-2010, 06:50 PM   #5
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Can anyone add more insight?
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      03-09-2010, 07:07 PM   #6
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I believe AA exhaust is 3" all the way through.... and it doesn´t seem to loose torque...
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      03-09-2010, 11:56 PM   #7
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Quote:
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I believe AA exhaust is 3" all the way through.... and it doesn´t seem to loose torque...
That's what the AA is known for... loss of low end torque.
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      03-10-2010, 01:27 AM   #8
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Just from watching that S3 dinan video, seems the Dinan is 2.75" all the way.
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      03-10-2010, 07:02 AM   #9
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Anyone know what the diameter size is on a Gintani X-pipe?
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      03-13-2010, 10:25 PM   #10
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+1 Also looking for borla x-pipe and Akra Evo size
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      03-14-2010, 04:40 AM   #11
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On the N/A motor, too large of a dia. pipe will reduce backpressure, but in doiing so will also reduce exhaust gas velocity, which is what is important to making power in a N/A motor. This is why there are X-pipes, to create a scavenging affect. The scavenging effects creates a negative pressure at the crossing of the Xpipe which sucks the exhaust gas and increases exhaust velocity, making more power and torque.
In contrast, on a FI motor, The larger the pipe, the better, and the least backpressure is whats important.
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