10-31-2014, 05:16 PM | #67 | |
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Here is a friend of mine @JK135i with a N54, 135i... his exhaust at this time had a aftermarket muffler with a straight pipe/mid. Maybe he will chime in on this thread... Anyways his car was loud! So loud you could hear him a few km's away!
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12-11-2014, 08:23 PM | #68 | |
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There is a reason why BMW does certain things.
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12-12-2014, 11:57 AM | #69 |
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Wanting to quiet the resonances at 2300 and 2800 rpm, I replaced the y-pipe in my 1M with the resonator from Dack's 135.
It turned down the resonances a bit, but they are still there. More acceptable for my money, but still mildly annoying. |
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12-12-2014, 04:01 PM | #70 | |
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Here...
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12-12-2014, 06:14 PM | #71 | |
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I had already done the dynamat thing in the trunk (with a lot more than you used, and a carpet scrap to fill the area flush) with only slight improvement. |
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12-12-2014, 08:22 PM | #72 |
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Only way to get rid of it -- as opposed to simply dampening the noise a bit -- would be with a tuned helmholtz resonator.
Some very high end exhausts (perhaps Akrapovic) have them as integral part of their systems. Neil |
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12-14-2014, 12:02 PM | #74 |
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This is essentially the N55 mid-pipe with two add'l cats. Should be quieter than a 135, theoretically.
Last edited by EldRick; 12-14-2014 at 03:25 PM.. |
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05-10-2015, 05:02 PM | #76 |
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Resonator update
Update on the 135 y-resonator:
I'm pretty sure it's not just my ears, but over the 3000 miles it has been installed, my 1M (with Dack's 135 y-resonator) has become considerably less noisy, and the resonances at 2300 and 2800 rpm are now greatly reduced. When the 135 y-pipe was first installed, I was a bit disappointed that it didn't reduce exhaust noise more, but at this point it is acceptable. To me it sounds like a BMW 6 is supposed to sound - normally muted in driving around town, but developing a nice smooth snarl when wide open. I don't have a good explanation for this, but I'm pretty sure the change is real. Maybe oil/carbon buildup on the pipes or on the stuffing makes it more effective at soaking up sound? Theories welcome... |
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05-11-2015, 01:36 AM | #77 | |
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The change in sound, is real. It's the same thing forum members report after installing a PE. After a few thousand miles the tone of the exhaust changes. For me, I noticed this after 6K miles of driving. I believe its the carboning up of the exhaust that's responsible. Dack
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05-11-2015, 06:06 PM | #78 |
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I put the Mad Dad mids on last August and have driven about 6000 miles since then. The exhaust has finally "matured" after its first track day last month, noticeably more snarl now even with modest acceleration, half throttle. It is exactly what I had hoped for, finally!
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05-13-2015, 03:57 PM | #79 |
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Akra + N55 mids: during 'spirited' Autobahn runs, after some time I start to hear a kind of 'double bass' whenever I floor the pedal. Hard to describe this phenomenon, but it sounds as if an extra rumble is added. Dies down when engine gets less stressed. Very likely heat-related.
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05-18-2015, 06:34 PM | #80 |
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Artemis Have you checked the clearance around the exhaust when it's hot? Perhaps it is touching the body somewhere when it heats up?
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05-24-2015, 04:54 PM | #81 | |
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05-24-2015, 05:20 PM | #82 | |
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I may run a quick check next time at some exit of the Autobahn (though a bit complicated to spot anything, even when crawling a bit under it, as the car sits already low). Don't underestimate the degree of heat flowing through the system when the car is seriously pushed.
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11-18-2015, 08:32 PM | #83 | ||
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BMW 1M midpipe: http://www.realoem.com/bmw/enUS/show...diagId=18_0770
And also the difference regarding the BMW 1M axle back exhaust: http://www.realoem.com/bmw/enUS/show...diagId=18_0932
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12-04-2015, 12:43 AM | #84 |
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Have a question regarding the secondary cats as I cannot find my answer anywhere, figured this is would be an appropriate place to get the info. ~How restrictive are the secondary cats? I read in some e90posts that the primary are 400 cell and the secondary are 200 cell. I understand the 1M OEM DPs are less restrictive. Not sure about the mid pipe section. It matters as I am tossing around the idea of ordering some HJS 100-200 cell race cats. If the OEM cats are 200s then I will use the OEM mids (fully catlless now) Thnx
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12-04-2015, 03:41 AM | #85 | |
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I think it was Harold at HP Auto HP Autosport that said it. I know the primary cats are also different - like you mentioned above, they flow more than the 135i N54 ones. 1M mid pipe w/cats... p/n 18307845669 http://www.realoem.com/bmw/enUS/part...669&series=E82 135i N54 mid pipe w/cats... p/n 18307559994 http://www.realoem.com/bmw/enUS/part...%0918307559994
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12-04-2015, 09:43 AM | #86 | |
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12-04-2015, 01:35 PM | #87 |
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Will do, and thnx for the response Dackel
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