ZPOST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   ZPOST > BMW Z4 Technical Talk > Engine, Exhaust, Drivetrain Modifications
  TireRack

SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS!
Post Reply
 
Thread Tools Search this Thread
      04-07-2014, 03:38 PM   #1
intoflatlines
Lieutenant
intoflatlines's Avatar
United_States
67
Rep
501
Posts

Drives: Z4MR, E34, E30
Join Date: Mar 2013
Location: Chicago

iTrader: (0)

Is the resonator/muffler the source of the drone?

I've driven straight piped cars before. None of them drone as terribly as my Z4M w/ muffler delete, replaced with resonators. I have heard that the RPI exhaust (I think?) drones a lot too. My drone seems to be more vibration based, in that even if I put earplugs in, the volume isn't decreased all that much. It's a really deep drone.

So, I'm wondering... do you think that the exhaust gases flowing through the resonators are attenuating the sound heard from the outside, but transferring that energy in the form of vibrations throughout the rest of the car?

Maybe the only thing I can do to test is remove the resonators completely and drive around the block just dumping the exhaust after the axle. Do straight piped Z4Ms drone a lot?

Physics isn't my strong suit, so please forgive me if everything I just wrote is crap.

Last edited by intoflatlines; 04-08-2014 at 07:17 PM..
Appreciate 0
      04-08-2014, 04:39 PM   #2
h3patik
New Member
0
Rep
8
Posts

Drives: BMW Z4 2.5
Join Date: Feb 2014
Location: PT

iTrader: (0)

Hi,
Delete the resonators and add just a good backbox
Appreciate 0
      04-19-2014, 12:33 AM   #3
intoflatlines
Lieutenant
intoflatlines's Avatar
United_States
67
Rep
501
Posts

Drives: Z4MR, E34, E30
Join Date: Mar 2013
Location: Chicago

iTrader: (0)

So I tested by removing the resonators/mufflers and it still had drone. It was reduced a little bit. Exterior noise was noticeably louder. It was very raspy under WOT. Not worth it for the minor reduction in drone.

You're saying to get an aftermarket X-pipe? And different mufflers? Any custom options for standalone mufflers or are people just buying the pre-made setups?
Appreciate 0
      04-20-2014, 11:30 AM   #4
DRedman45
Lieutenant
DRedman45's Avatar
35
Rep
441
Posts

Drives: E86 //M coupe
Join Date: Oct 2012
Location: Northern va

iTrader: (0)

The s54 is a noisy motor you need resonators closer to the headers to kill rasp and most drone...but it will always drone
__________________
2007 //M Coupe. BSM. Fabspeed headers. Catless. BMS x-pipe. Strömung cans. evolve tune. Turner CSL airbox. Airrex air suspension with autopilot v2 management.

My Build Thread
Appreciate 0
      04-22-2014, 11:04 AM   #5
p1nk50ck
HNIC
United_States
31
Rep
177
Posts

Drives: Z4M Coupe
Join Date: Aug 2013
Location: Arlington, VA

iTrader: (0)

http://www.zpost.com/forums/showthread.php?t=747182

http://www.dkfperformance.com/products.html

these might help?
Appreciate 0
      04-22-2014, 12:43 PM   #6
Arsonism
Captain
Arsonism's Avatar
United_States
158
Rep
747
Posts

Drives: '08 M Coupe
Join Date: Oct 2013
Location: Austin, TX

iTrader: (3)

There is a thread out there of creating a horseshoe or U shaped pipe at specific length to remove drone. Decent amount of science behind it but is proven to work. If you're already custom exhaust all the way through you might want to give this a try with a muffler shop or someone who has welding capabilities. I'll see if I can find the thread.
Appreciate 0
      04-22-2014, 12:55 PM   #7
Finnegan
Dog Listener
Finnegan's Avatar
United_States
701
Rep
7,850
Posts

Drives: Z4M/. Z3M, E36/46 M3
Join Date: Oct 2008
Location: Teaching the dog to slalom

iTrader: (22)

Skiddish has it right, there's a way to cancel drone.

Here is the thread re: U Pipe.

And reference material.
Appreciate 1
      04-22-2014, 01:30 PM   #8
Arsonism
Captain
Arsonism's Avatar
United_States
158
Rep
747
Posts

Drives: '08 M Coupe
Join Date: Oct 2013
Location: Austin, TX

iTrader: (3)

Quote:
Originally Posted by Finnegan View Post
Skiddish has it right, there's a way to cancel drone.

Here is the thread re: U Pipe.

And reference material.
This man's got it. Thanks for digging for me!
Appreciate 0
      04-26-2014, 01:18 AM   #9
Finnegan
Dog Listener
Finnegan's Avatar
United_States
701
Rep
7,850
Posts

Drives: Z4M/. Z3M, E36/46 M3
Join Date: Oct 2008
Location: Teaching the dog to slalom

iTrader: (22)

Quote:
Originally Posted by Skiddish View Post
This man's got it. Thanks for digging for me!
You're welcome! Have it book-marked, since it's on the "to do" list for after moving day.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 09:17 PM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST