Front Section / X-Pipe Exhaust Diameters

masitr · 03-06-2010, 06:50 PM

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.

MrHarris · 03-06-2010, 07:17 PM

Should be 2.5" going to 3" will lose major torque.

Lemans_Blue_M · 03-06-2010, 07:37 PM

Quote:

Originally Posted by MrHarris

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.

masitr · 03-07-2010, 08:42 PM

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.

masitr · 03-09-2010, 05:50 PM

Can anyone add more insight?

ee8 · 03-09-2010, 06:07 PM

I believe AA exhaust is 3" all the way through.... and it doesn´t seem to loose torque...

aus · 03-09-2010, 10:56 PM

Quote:

Originally Posted by ee8

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.

MrHarris · 03-10-2010, 12:27 AM

Just from watching that S3 dinan video, seems the Dinan is 2.75" all the way.

808E90 · 03-10-2010, 06:02 AM

Anyone know what the diameter size is on a Gintani X-pipe?

masitr · 03-13-2010, 09:25 PM

+1 Also looking for borla x-pipe and Akra Evo size

dvpouldar26 · 03-14-2010, 04:40 AM

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.

03-06-2010, 06:50 PM	#1
masitr Private First Class 23 Rep 148 Posts Drives: E92 M3 6MT Join Date: Jan 2009 Location: NW Ohio iTrader: (6)	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, 07:17 PM	#2
MrHarris yodog 197 Rep 5,026 Posts Drives: '86 Corolla Join Date: Jun 2007 Location: Diamond Bar, Ca iTrader: (5) Garage List 2009 BMW [10.00]	Should be 2.5" going to 3" will lose major torque. __________________ 2009 E92 M3 \| Alpine White \| Black Extended \| Advan RS \| Turner Test Pipes \| Dinan Axle-Back \| OETuning \| Eibach Springs \| UUC SSK \| VRS Front Lip \| VRS Type I Diffuser \| Matte Black \| RPi Scoops \| MS Filter \| Yokohama AD08 \| F1 Pinnacle Special Thanks: Gintani \| OETuning \| eAs
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03-07-2010, 08:42 PM	#4
masitr Private First Class 23 Rep 148 Posts Drives: E92 M3 6MT Join Date: Jan 2009 Location: NW Ohio iTrader: (6)	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 05:49 PM..
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03-09-2010, 05:50 PM	#5
masitr Private First Class 23 Rep 148 Posts Drives: E92 M3 6MT Join Date: Jan 2009 Location: NW Ohio iTrader: (6)	Can anyone add more insight?
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03-09-2010, 06:07 PM	#6
ee8 Private First Class 7 Rep 148 Posts Drives: E92 M3 Join Date: Oct 2009 Location: Portugal iTrader: (0) Garage List 2008 BMW M3 [6.40]	I believe AA exhaust is 3" all the way through.... and it doesn´t seem to loose torque...
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03-10-2010, 12:27 AM	#8
MrHarris yodog 197 Rep 5,026 Posts Drives: '86 Corolla Join Date: Jun 2007 Location: Diamond Bar, Ca iTrader: (5) Garage List 2009 BMW [10.00]	Just from watching that S3 dinan video, seems the Dinan is 2.75" all the way. __________________ 2009 E92 M3 \| Alpine White \| Black Extended \| Advan RS \| Turner Test Pipes \| Dinan Axle-Back \| OETuning \| Eibach Springs \| UUC SSK \| VRS Front Lip \| VRS Type I Diffuser \| Matte Black \| RPi Scoops \| MS Filter \| Yokohama AD08 \| F1 Pinnacle Special Thanks: Gintani \| OETuning \| eAs
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03-10-2010, 06:02 AM	#9
808E90 808E90 233 Rep 4,047 Posts Drives: E90 ///M Join Date: Aug 2008 Location: Aloha State iTrader: (21)	Anyone know what the diameter size is on a Gintani X-pipe?
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03-13-2010, 09:25 PM	#10
masitr Private First Class 23 Rep 148 Posts Drives: E92 M3 6MT Join Date: Jan 2009 Location: NW Ohio iTrader: (6)	+1 Also looking for borla x-pipe and Akra Evo size
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03-14-2010, 04:40 AM	#11
dvpouldar26 Major 64 Rep 1,498 Posts Drives: 2008 e92 328i, Porsche 987.1 Join Date: May 2008 Location: Beverly Hills, CA iTrader: (4)	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. __________________ E92 328i Jet Black / Gloss Black Grilles / 8000k D1S low beam / 6000k HID fogs / GP Thunder 8500k angels & cornering bulbs / black reflectors / gloss black vinyled window trim / tints / smoked rear turn signals / black roundels / AC Schnitzer roof spoiler / VRS style decklid spoiler / Matte black Stripes / Rear fogs / matte mirrors / 19" LM reps / APR lip
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