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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 > Exhaust? X-pipe or straight through-why?



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      03-21-2007, 10:55 AM   #1
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Exhaust? X-pipe or straight through-why?

Ok, we now have several manufacturers coming out with exhaust for our cars. Some have a built in x-pipe(crossover) and others are straight through.

Shiv's is straight through and recommends exhaust without the x-pipe to get the full potential.

If thats the case, why are these top-notch companies'(Milltek) putting crossovers in theirs. Obviously they do R&D so they must have come up with some idea.

If it comes down to sound being muffled then I understand, but if people want performance, they should have options. At least available baffles that you can put in or take out to keep sound down. Thats something Thermal offers on their exhaust for Audis.
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      03-21-2007, 11:20 AM   #2
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Having a X pipe is in my opinion the most retarded design ever made for an exhaust. What are the really advantages of a design that makes the flow to be altered and disrupted?

Go to your backyard and have to water hoses with water shotting at 100mph collide and see what happens.

Water and gases have some flow similarities, the flow of less resistance overrules. Why in the hell would you want a X pipe to disrupt and slow down flow?

Not to mention that whenever maintenance needs to be done the weight of both pipings are increased because the cat-backs are united.

If someone can please "explain" the benefits of a X pipe maybe I buy beer.

my .2c

I am with Vishnu on that, straight flow always overrules on turbo cars.

Carlos
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      03-21-2007, 11:33 AM   #3
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      03-21-2007, 11:33 AM   #4
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Quote:
Originally Posted by Evo8MRto335I View Post
Having a X pipe is in my opinion the most retarded design ever made for an exhaust. What are the really advantages of a design that makes the flow to be altered and disrupted?
My point exactly. So why is every exhaust being made now pretty much incorporating this backwards design?
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      03-21-2007, 12:47 PM   #5
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Quote:
Originally Posted by HyperM3 View Post
Ok, we now have several manufacturers coming out with exhaust for our cars. Some have a built in x-pipe(crossover) and others are straight through.

Shiv's is straight through and recommends exhaust without the x-pipe to get the full potential.

If thats the case, why are these top-notch companies'(Milltek) putting crossovers in theirs. Obviously they do R&D so they must have come up with some idea.

If it comes down to sound being muffled then I understand, but if people want performance, they should have options. At least available baffles that you can put in or take out to keep sound down. Thats something Thermal offers on their exhaust for Audis.
Where do you find the info that Milltek has X-pipe? I hope not...
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      03-21-2007, 01:01 PM   #6
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Quote:
Originally Posted by bnj View Post
Where do you find the info that Milltek has X-pipe? I hope not...
I cant find pics anymore of the Miltek but I see the Ultimate Racing and CPE exhausts both have it.
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      03-21-2007, 01:11 PM   #7
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AA doesn't have X-Pipe. I believe Milltek doesn't have it either. Don't know for sure, though.
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      03-21-2007, 01:38 PM   #8
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      03-21-2007, 01:40 PM   #9
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Quote:
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BD
Awesome job at trying to get your post count up!!!
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      03-21-2007, 01:45 PM   #10
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Awesome job at trying to get your post count up!!!

trust me if my intentions were as you comment then i could have 4-500 by now BUT since it wasn't i'd have to say it was done in order to receive email notification.

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      03-21-2007, 01:53 PM   #11
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Quote:
Originally Posted by Big Daddy View Post
trust me if my intentions were as you comment then i could have 4-500 by now BUT since it wasn't i'd have to say it was done in order to receive email notification.

BD
For future reference, you can just go to the "thread tools" pull down at the top and click "subscribe to thread". However, if you knew about that then you were not adding anything to the thread except a count in your favor.
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      03-21-2007, 01:54 PM   #12
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i'm aware of that thanks anyway. and BTW don't sweat my post count or anyone elses just worry about yourself and things will carry on as normal.

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      03-21-2007, 01:59 PM   #13
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I think but dont hold me to it but the crossover pipe (x-pipe) may reduce the raspy sound in the exhaust. Since most companies are using straight thru resonated design mufflers the crossover pipe may help balance the air going thru and control the sound a bit.
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      03-21-2007, 02:06 PM   #14
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Quote:
Originally Posted by Evo8MRto335I View Post
Having a X pipe is in my opinion the most retarded design ever made for an exhaust. What are the really advantages of a design that makes the flow to be altered and disrupted?

Go to your backyard and have to water hoses with water shotting at 100mph collide and see what happens.

Water and gases have some flow similarities, the flow of less resistance overrules. Why in the hell would you want a X pipe to disrupt and slow down flow?

Not to mention that whenever maintenance needs to be done the weight of both pipings are increased because the cat-backs are united.

If someone can please "explain" the benefits of a X pipe maybe I buy beer.

my .2c

I am with Vishnu on that, straight flow always overrules on turbo cars.

Carlos
Alright! Free beer!

This is a possible explanation concerning your fluid dynamics question. There is laminar and turbulent flow. X-over creates turbulent flow. Believe it or not, turbulent flow moves faster than laminar flow. This has been very well documented for flow kinematics. Thus the possible X-over design. I believe if there are fins arranged inside the tube to create a vortex, such as the spiral grooves in the gun barrel, exhaust may exit faster.
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      03-21-2007, 06:53 PM   #15
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I was always under the impression that X-pipes offer substantially better balancing of the exhaust gas pulses. It all comes down to gas velocity. The X-pipe will have better flow.
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      03-21-2007, 07:14 PM   #16
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Quote:
Originally Posted by Ryan@Eisenhaus View Post
The X-pipe will have better flow.
Which coming from an exhaust maker brings me to my original question. Why would Shiv say his exhaust is better without it and why would Miltek(I was wrong originally) also not incorporate one? I can only assume that everyone is dynotesting theirs.

Shiv or anyone else(manufacturing exhaust) care to chime in at anytime please.
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      03-22-2007, 02:55 AM   #17
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http://www.moddedmustangs.com/ford-m...-upgrades.html

This site explains it, read the Mid pipes section.
And this
http://www.drgas.com/articles/art_syncronicity.php
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      03-22-2007, 03:10 AM   #18
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This site actually has a better explanation-- I don't know whether or not it applies to the 335i, but the stock exhaust DOES have an x-pipe, if I am correct...

http://www.enjoythedrive.com/content/?id=10185
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      03-22-2007, 03:16 AM   #19
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335 has H pipe.
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      03-22-2007, 03:33 AM   #20
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Originally Posted by ac2 View Post
Thanks it's an intresting read
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      03-22-2007, 03:34 AM   #21
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Quote:
Originally Posted by ac2 View Post
335 has H pipe.
it has an X-Pipe before the rear axle I saw it yesterday when I was disgussing exhaust options with an installer he was goin on and on about it.
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      03-22-2007, 11:56 AM   #22
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Quote:
Originally Posted by Ryan@Eisenhaus View Post
I was always under the impression that X-pipes offer substantially better balancing of the exhaust gas pulses. It all comes down to gas velocity. The X-pipe will have better flow.
I FOUND U! WHEN IS THE EXHAUST COMING OUT!!!!
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