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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > X Pipe real purpose?



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      07-20-2011, 07:24 PM   #1
AKG
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X Pipe real purpose?

Can anyone explain please...
Is it for a better sound? or lower noise?
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      07-20-2011, 07:30 PM   #2
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They're to improve exhaust pulse balancing/exhaust scavenging. Essentially the goal is to make the velocity and flow better balanced on both sides.

A smoother sound (and at times higher-pitched) is a result of that balancing.

I'm sure someone else can probably explain it better/more accurately.
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      07-20-2011, 09:40 PM   #3
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Helps with drone.
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      07-20-2011, 11:22 PM   #4
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An x-pipe is used to equalize flow between the two exhaust banks. Crossovers, x-pipes & h-pipes, usually improve tq and hp numbers. With a turbo car it really has limited use other than modifying the exhaust note/tone, since exhaust scavenging becomes irrelevant and minimizing exhaust backpressure becomes the priority.
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      07-21-2011, 08:44 AM   #5
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Quote:
Originally Posted by ///M3THOD View Post
With a turbo car it really has no use other than modifying the exhaust note/tone, since exhaust scavenging becomes irrelevant and minimizing exhaust backpressure becomes the priority.
I'm not sre there is "no use" on a turbo car as the HKS exhaust system has a true H Pipe and it makes more power (relatively) than most of the other DP Back Exhaust Systems. Seems to be some gain from it.
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      07-21-2011, 11:23 AM   #6
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Quote:
Originally Posted by bigdaddycane View Post
I'm not sre there is "no use" on a turbo car as the HKS exhaust system has a true H Pipe and it makes more power (relatively) than most of the other DP Back Exhaust Systems. Seems to be some gain from it.
Yes that is true.. it still serves the same purpose of equalizing the exhaust velocity on the two banks. Perhaps it relives some of the pressure on whichever line has more backpressure but with a turbo car the least amount of backpressure is ideal.

What I was trying to say is that they are of limited function on a turbo car, and are not as vital as on a NA car, especially those with a V engine configuration.
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Last edited by ///M3THOD; 07-21-2011 at 03:11 PM..
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      07-21-2011, 01:49 PM   #7
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Thanks all for the input.

You think an X pipe has a better effect if it is placed at the front or rear sections? in front or behid resonators? you realy think it would help with the drone?
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      07-21-2011, 01:54 PM   #8
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Quote:
Originally Posted by ///M3THOD View Post
An x-pipe is used to equalize flow between the two exhaust banks. Crossovers, x-pipes & h-pipes, usually improve tq and hp numbers. With a turbo car it really has limited use other than modifying the exhaust note/tone, since exhaust scavenging becomes irrelevant and minimizing exhaust backpressure becomes the priority.
^This..and just to add..turbos actually love the least restriction possible. This is the nature of forced induction there is not a need to equalize the gas pulses for scavenging like u need in an N/A..hence why running an H X pipe or even a cat on an N/A usually nets some low end power...but for a turbo car other than sound..not a huge benefit.

I run a completely divorced pipe exhaust..the sound is more a function of well built mufflers, than an X pipe
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      07-24-2011, 09:58 PM   #9
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Anyone with experience with this pls???

"You think an X pipe has a better effect if it is placed at the front or rear sections? in front or behid resonators? you realy think it would help with the drone?"
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      07-24-2011, 10:11 PM   #10
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Quote:
Originally Posted by AKG View Post
Anyone with experience with this pls???

"You think an X pipe has a better effect if it is placed at the front or rear sections? in front or behid resonators? you realy think it would help with the drone?"
No
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