X pipe clarification....
Thread Starter
Super Member
Joined: Apr 2009
Posts: 518
Likes: 4
From: laguna philippines
99 model w210 e55 amg
X pipe clarification....
hi guys! what really does the X pipe do? i know it repalces the resonator but besides replacing the resonator what does it do? cant we just replace the resonator with a straight pipe? why use the x pipe? whats the explanation on this? thanks!
Member
Joined: Apr 2008
Posts: 170
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From: MD
2008 EVO X GSR
Its makes more power then straight pipes and more refined tone to the exhaust note. I have had primay high flows with straight pipes w/o x-pip and with the x-pipe, x-pipe is a lot better and sounds a million times nicer. the top end "breathes" better too.
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Joined: Feb 2008
Posts: 1,803
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From: Charleston, SC
GL450
This isn't a great explanation, but it's a start:
http://www.carcraft.com/techarticles...ion/index.html
Basically, you get two benefits over a straight pipe.
First, exhaust gas has two exit paths instead of just one. Exhaust gas comes in pulses, rather than as a continuous flow, based on the firing order of the engine. A pulse coming down the passenger bank exhaust path hits the X pipe and can now proceed through both the passenger and driver exhaust path. So it effectively increases the capacity of the system versus confining exhaust gas to a single path.
Second, it increases scavenging (the effect of vacuum). An exhaust pulse is a chunk of air moving down the exhaust pipe. Like any moving object, it creates a partial vacuum behind it (think about how a large truck creates a draft behind it). This vacuum helps the engine operate more efficiently (it's pulling the bad exhaust out of the engine and pulling good fresh air into the engine). It's kind of like a very (very) small supercharger, but it works by creating negative pressure in the exhaust side rather than positive pressure in the intake side. With straight pipes, an exhaust pulse from one bank only creates a vacuum on that bank. With an x pipe, that scavenging effect is created on both banks, as it can lower the pressure of the other bank as it travels through the X pipe.
This is probably a scientifically mediocre but hopefully easy to understand explanation. If you search around Google, there is much better reading out there.
http://www.carcraft.com/techarticles...ion/index.html
Basically, you get two benefits over a straight pipe.
First, exhaust gas has two exit paths instead of just one. Exhaust gas comes in pulses, rather than as a continuous flow, based on the firing order of the engine. A pulse coming down the passenger bank exhaust path hits the X pipe and can now proceed through both the passenger and driver exhaust path. So it effectively increases the capacity of the system versus confining exhaust gas to a single path.
Second, it increases scavenging (the effect of vacuum). An exhaust pulse is a chunk of air moving down the exhaust pipe. Like any moving object, it creates a partial vacuum behind it (think about how a large truck creates a draft behind it). This vacuum helps the engine operate more efficiently (it's pulling the bad exhaust out of the engine and pulling good fresh air into the engine). It's kind of like a very (very) small supercharger, but it works by creating negative pressure in the exhaust side rather than positive pressure in the intake side. With straight pipes, an exhaust pulse from one bank only creates a vacuum on that bank. With an x pipe, that scavenging effect is created on both banks, as it can lower the pressure of the other bank as it travels through the X pipe.
This is probably a scientifically mediocre but hopefully easy to understand explanation. If you search around Google, there is much better reading out there.
Thread Starter
Super Member
Joined: Apr 2009
Posts: 518
Likes: 4
From: laguna philippines
99 model w210 e55 amg
very nice xplanation saints! so where is the best place to put the x pipe in the xhaust? is it where the resonator used to be or closer to the engine? thanks and alos whats the best design of x pipe? can anyone pls post pics? thanks!
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Joined: Jun 2009
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W210 E55 AMG
Please advice, as I was thinking of putting the x-pipe in place of the secondary cats, but if it will be of more benefit to replace the resonator, then that's where I'll put it.
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Joined: Nov 2008
Posts: 253
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From: DC Metro
W210 E55, W211 E3504M, E90 325i
Most folks (with all cats in place) have the x-pipe where the resonator used to be.
Senior Member
Joined: Nov 2008
Posts: 253
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From: DC Metro
W210 E55, W211 E3504M, E90 325i
They also sell Magnaflow brand 45 degree mandrel pipes to go with the Magnaflow x-pipes.
Senior Member
Joined: Nov 2008
Posts: 253
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From: DC Metro
W210 E55, W211 E3504M, E90 325i
Actually I just did this mod this morning 
Its everything its cracked up to be although I was expecting more decibels. I'm definitely gonna source some high-flow cats now. I was leaning more on the conservative side and declined my exhaust guy's offer to cut the secondary cats out.
Its everything its cracked up to be although I was expecting more decibels. I'm definitely gonna source some high-flow cats now. I was leaning more on the conservative side and declined my exhaust guy's offer to cut the secondary cats out.
Junior Member
Joined: Jun 2009
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W210 E55 AMG
To further clarify, you're saying that the ideal place for the x-pipe is to put it in place of my secondary cats? Delete secondary and replace with x-pipe?
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Joined: Feb 2008
Posts: 1,803
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From: Charleston, SC
GL450
Agree. Generally you want the cross to occur when velocity is highest (to increase scavenging) and early in the system (the sooner the exhaust pulse can split itself, the lower the restriction). Most people pick the resonator location because they want to remove it anyway. Doing it closer to the engine (i.e. where the cats are) would probably be slightly better. Bear in mind the difference here is so small it's probably only theoretical (i.e. couldn't be accurately measured, even on a dyno).
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Joined: Feb 2008
Posts: 1,803
Likes: 12
From: Charleston, SC
GL450
There are a ton of companies that make pre-made ones, I'm sure you can find someone that can ship (or even someone local). Also, you can have your exhaust shop make one, it's not that hard. 4 bent pipes, cut it so they line up in an X, and weld.
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Joined: Feb 2008
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From: Bostonian Ma
2012 CLS63 AMG
I loooooove my X pipe going with high flows as well, this will make her sound really sweet 
MBWorld Fanatic!
Joined: Feb 2008
Posts: 1,280
Likes: 4
From: Bostonian Ma
2012 CLS63 AMG
This isn't a great explanation, but it's a start:
http://www.carcraft.com/techarticles...ion/index.html
Basically, you get two benefits over a straight pipe.
First, exhaust gas has two exit paths instead of just one. Exhaust gas comes in pulses, rather than as a continuous flow, based on the firing order of the engine. A pulse coming down the passenger bank exhaust path hits the X pipe and can now proceed through both the passenger and driver exhaust path. So it effectively increases the capacity of the system versus confining exhaust gas to a single path.
Second, it increases scavenging (the effect of vacuum). An exhaust pulse is a chunk of air moving down the exhaust pipe. Like any moving object, it creates a partial vacuum behind it (think about how a large truck creates a draft behind it). This vacuum helps the engine operate more efficiently (it's pulling the bad exhaust out of the engine and pulling good fresh air into the engine). It's kind of like a very (very) small supercharger, but it works by creating negative pressure in the exhaust side rather than positive pressure in the intake side. With straight pipes, an exhaust pulse from one bank only creates a vacuum on that bank. With an x pipe, that scavenging effect is created on both banks, as it can lower the pressure of the other bank as it travels through the X pipe.
This is probably a scientifically mediocre but hopefully easy to understand explanation. If you search around Google, there is much better reading out there.
http://www.carcraft.com/techarticles...ion/index.html
Basically, you get two benefits over a straight pipe.
First, exhaust gas has two exit paths instead of just one. Exhaust gas comes in pulses, rather than as a continuous flow, based on the firing order of the engine. A pulse coming down the passenger bank exhaust path hits the X pipe and can now proceed through both the passenger and driver exhaust path. So it effectively increases the capacity of the system versus confining exhaust gas to a single path.
Second, it increases scavenging (the effect of vacuum). An exhaust pulse is a chunk of air moving down the exhaust pipe. Like any moving object, it creates a partial vacuum behind it (think about how a large truck creates a draft behind it). This vacuum helps the engine operate more efficiently (it's pulling the bad exhaust out of the engine and pulling good fresh air into the engine). It's kind of like a very (very) small supercharger, but it works by creating negative pressure in the exhaust side rather than positive pressure in the intake side. With straight pipes, an exhaust pulse from one bank only creates a vacuum on that bank. With an x pipe, that scavenging effect is created on both banks, as it can lower the pressure of the other bank as it travels through the X pipe.
This is probably a scientifically mediocre but hopefully easy to understand explanation. If you search around Google, there is much better reading out there.
