5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
my guess is that has something to do with if you have another exhaust pipe, but since you dont have another exhaust pipe(dont have dual exhaust) its blocked off.. and yes, it should be considerably louder w/it off
i don't think it is just something to block the exhaust incase the car had duel exhaust becasue in the picture the opening for the piece goes towards the front of the car if i'm not misteaken. i don't know for sure what it is but my guess would be some sort of resinator to give the exhaust a sound that the engineers at the factory wanted.
Actually it is meant for sound deadening. That whole funky design of there being like a "chopped off" exhaust is totally intentional and was developed for noise reduction due to the stricter noise laws in Europe. Its part of the Helmholtz noise cancellation system. Do a google search on it.
A quick question: Does exhaust come out that hole when it is removed. If so, I would think you would be changing the tuning of the way exhaust is meant to go down the pipe. This gives an easy access for the exhaust to escape, but not neccessarily at the proper point. You actually could get less performance out of it. If a LOT of exhaust comes out that hole and there is not enough pressure to force out condensation from the heating/cooling down process, the back half of your exhaust may rust out over time. If exhaust doesnt come out of there, then you probably are ok.
I am sure BMW wouldnt have spent R&D money to make this piece if they didnt feel it was important to have on there. I know in the car audio world, adding weight to a panel makes that panel harder to rattle from the bass speakers, the whole idea behind sound deadening. I would search around a little more.
-There are 10 kinds of people. Those who understand binary, and those who do not.
-If we ever forget that we are One Nation Under God, then we will be a nation gone under...Ronald Reagan
I understand the rust problem, thats why I am just going to take it off sometimes (if it does make a dramatic sound difference) if im going cruzin or whatever. It takes literally seconds to put on and off and no need to jack the car up. So i'm gonna get a second opinion on if its louder. I won't take it off for more than a day if I ever do it again. Why risk it?
please elaborate Dirty Tool. So I should cap off the exhaust pipe and just have that pipe? Or should I just take it off and see the difference? I have that dumb testing for school tomorrow so I have tons of time and no hw :-).
I know its pretty pointless to take it off, but ohwell... like i said before its not coming off for more than a few hours
just discovered that no air comes out of the hole with that weird heavy thing I have pictured above. When you cover the exhaust it gets pressure and blows the cap off, so this is pointless and lame. Dont try it...
Noise & vibration control was something I did in a previous career. The device you identified is definitely there to absorb unwanted noise, as in a helmholtz resonator as DT pointed out. Additionally, I suspect that, due to its size and weight, it may also serve to balance out vibrations in the exhaust pipe itself.
Speaking of helmholtz, there is a classic resonator chamber directly adjacent to, and similar in appearance to the muffler at the rear of an E39 540.
Likewise, there is a funny-looking appendix, uh, "thing", that provides a helmholtz cavity on the intake side as well. In the case of my 1999 540, it tucks up underneath the MAF sensor.
Good luck in your cause-and-effect research. let us know what you discover.
__________________ <span style='colorurple'>Eric S.</span>
2006 Honda Odyssey EXL-RES
2006 Honda Accord V6 EX-L Sedan
1999 BMW 540i 6-Speed (Sold to M3UOND on 9/21/06)
1991 Honda Civic Si - Occasional Beater
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.