07-12-2013, 04:29 PM | #1 |
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Mid pipe design and install...
I have been thinking about getting my mid pipe bought and installed, but was wondering about design and possibly getting one built to my specs and this got me thinking.
Is there any reason why no one has manufactured a replacement mid section pipe that is a single 3-3.5" pipe design rather than the two. i.e. does away with the two branch runs and goes with just a single 3" or 3.5" design with minimal length two branch split to pair up at the DP end? I have heard that some of the 135i cars preferred this design and have used this exhaust type setup. Pros and Cons please? |
07-13-2013, 02:33 PM | #5 |
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From what I know, I believe the single branch to increase back pressure which hurts overall horsepower but will increase torque. These effects are small overall, but still effects. Maybe an x-pipe would help balance both branches, but there isn't much real estate under there. The 1M doesn't need additional low end torque. The VW GTI benefits nicely from a single pipe as an example.
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08-02-2013, 08:51 AM | #7 |
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Thanks for the info guys. Was looking at a little more technical input or from those that might have done this mod/change.
I have owned a few FI cars and fully aware that back pressure is a no-no. NA cars are certainly a bit different in their exhaust designs to create some 'pulse'. |
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08-02-2013, 08:53 AM | #8 |
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08-02-2013, 11:21 AM | #9 |
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cross-sectional area:
3" pipe: 28.27 sqin 3.5" pipe: 38.48 sqin twin 2.5": 39.27 sqin The most volume is going to come from twin 2.5s. Berk and Maddad already make a great setup in that diameter. So why reinvent the wheel for less volume? You can pick up a set of either used in the $300s and you won't have potential dragging issues like you will with 3.5" single. A custom single will be much more expensive and the only positive is slightly less weight. A few pounds at the lowest point on the car is going to make no difference though. |
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08-02-2013, 04:16 PM | #10 | |
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Quote:
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08-04-2013, 04:03 PM | #11 |
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I have a custom mid-pipe on my 1M. The pipes merge just downstream of the downpipes and there is also a small resonator just before the flange that connects to the cat-back exhaust. Seems to work great.
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08-05-2013, 03:59 PM | #13 |
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COBB did the fabrication as part of several upgrades they did on my car while tuning the AccessPORT for various stages of hardware configurations. The exhaust system ended up with catted downpipes, this single mid-pipe, and an Eisenmann race cat-back exhaust. I like the sound--obviously more agressive than stock, but still reasonably quiet at crusing speeds.
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08-05-2013, 04:37 PM | #14 | |
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08-05-2013, 08:21 PM | #15 |
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Not a 1M but this car also has a 3.5" straight through exhaust.
http://www.1addicts.com/forums/showthread.php?t=852171 |
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08-06-2013, 09:45 AM | #16 |
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Thanks again guys. I heard that the 135 track and race cars do prefer the single pipe. Good bits of information here. I am not doing it for any weight saving etc. Just though one big single pipe might have produced better results and sound.
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