E90Post
 


VIBE Motorsports
 
BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > UK > UK Technical Forum > exhaust valve



Reply
 
Thread Tools Search this Thread
      05-25-2011, 01:37 PM   #1
acerboo
Brigadier General
 
Drives: e92 335d lci
Join Date: Jul 2008
Location: kent

Posts: 3,619
iTrader: (2)

exhaust valve

does anyone know what the valve in the exhaust tailpipe does
acerboo is offline   England
0
Reply With Quote
      05-25-2011, 02:06 PM   #2
ibanezking
Weekend Rockstar
 
ibanezking's Avatar
 
Drives: E92 M3
Join Date: Feb 2010
Location: Leigh, Lancs

Posts: 728
iTrader: (1)

it'll be along the lines :

half closed at lower revs - to keep low end torque by increasing back pressure

fully open at high revs - to give plenty of space for the burnt fuel/air to get out of.........


Yamaha's old bike system was called Exup or simply "powervalve" on the old 2 strokes
__________________
E92 M3 - Interlagos Blue and Black everything else!!!
ibanezking is offline   England
0
Reply With Quote
      05-25-2011, 04:13 PM   #3
EddyH
Private First Class
 
Drives: E87 118D
Join Date: May 2011
Location: United Kingdom

Posts: 147
iTrader: (2)

On the 335i it's just to reduce noise at cold start and cruising speeds.
EddyH is offline  
0
Reply With Quote
      05-25-2011, 04:37 PM   #4
m1bjr
LSD - No, you're not seeing things
 
m1bjr's Avatar
 
Drives: RS250 CUP
Join Date: Mar 2010
Location: Somerset UK

Posts: 3,313
iTrader: (4)

Send a message via MSN to m1bjr
Quote:
Originally Posted by EddyH View Post
On the 335i it's just to reduce noise at cold start and cruising speeds.
Not even at cruise.

Only during cold enrichment cycle.

You should hear it pop open once its off warm-up.
it doesnt close again unless its subzero.

You'll see easily from the vapour on a cold morning, that both are open quickly.
__________________
m1bjr is offline   United Kingdom
0
Reply With Quote
      05-25-2011, 06:27 PM   #5
EddyH
Private First Class
 
Drives: E87 118D
Join Date: May 2011
Location: United Kingdom

Posts: 147
iTrader: (2)

I wasn't sure as mine has been stuck open since I got the car. Not sure if the previous owner did it or if it's faulty.
EddyH is offline  
0
Reply With Quote
      05-26-2011, 02:28 AM   #6
creepy coupe
Major General
 
creepy coupe's Avatar
 
Drives: M235i
Join Date: Aug 2007
Location: UK

Posts: 8,171
iTrader: (2)

Garage List
2009 335i  [0.00]
I disconnected mine and it made a difference through most of the RPM range, but mostly around town, under light throttle. I personally liked the sound.
creepy coupe is offline  
0
Reply With Quote
      05-26-2011, 09:15 AM   #7
335rocks
Lieutenant
 
Drives: E92 335i M Sport
Join Date: Sep 2008
Location: UK

Posts: 519
iTrader: (0)

Quote:
Originally Posted by m1bjr View Post
Not even at cruise.

Only during cold enrichment cycle.

You should hear it pop open once its off warm-up.
it doesnt close again unless its subzero.

You'll see easily from the vapour on a cold morning, that both are open quickly.
The vacuum flap is definitely operated when warm on low load/RPMs. You can hear this while idling and crusing on the motorway. The exhaust noise is reduced quite a bit. Probably more on the coupe than the sedan. During the startup phase the left flap is fully closed. I'm not sure to what extent the flap is adjusted, but if you disconnect the control cable to the vacuum actuator the flap will be fully open (spring loaded). Quite cool around town, but can be a bit boomy on the motorway and longer trips.
335rocks is offline   United Kingdom
0
Reply With Quote
      05-26-2011, 09:40 AM   #8
doughboy
Major General
 
doughboy's Avatar
 
Drives: E91 335i Sold.
Join Date: Jan 2009
Location: UK

Posts: 6,370
iTrader: (2)

Quote:
Originally Posted by m1bjr View Post
Not even at cruise.

Only during cold enrichment cycle.

You should hear it pop open once its off warm-up.
it doesnt close again unless its subzero.

You'll see easily from the vapour on a cold morning, that both are open quickly.
It does open after the fast cold idle, but it's used by the DME again on light throttle cruise and at other specified load/throttle points to control noise.

I tried disconnecting mine so it stayed open, it sounds loud at warm up but the boominess at about 80 on light throttle is horrendous. There is increased boom noise at other times too.

Saves BMW having to design a perfect exhaust, just use a flap to get rid of unwanted resonance.

Last edited by doughboy; 05-26-2011 at 09:47 AM.
doughboy is offline   United Kingdom
0
Reply With Quote
      05-26-2011, 09:42 AM   #9
ibanezking
Weekend Rockstar
 
ibanezking's Avatar
 
Drives: E92 M3
Join Date: Feb 2010
Location: Leigh, Lancs

Posts: 728
iTrader: (1)

so it has no performance implications............ just noise??
__________________
E92 M3 - Interlagos Blue and Black everything else!!!
ibanezking is offline   England
0
Reply With Quote
      05-26-2011, 09:45 AM   #10
doughboy
Major General
 
doughboy's Avatar
 
Drives: E91 335i Sold.
Join Date: Jan 2009
Location: UK

Posts: 6,370
iTrader: (2)

Hi max - not jealous of your car at all (git)

A car tail pipe flap is only for noise control, your reference to Exup type valves at the manifold end nearer the engine are to benefit normally aspirated engines by altering the exhaust back pressure and pressure pulses etc.

Especially as the 335i/d are turbo engines then complex back pressure theory doesn't apply after the turbocharger.
doughboy is offline   United Kingdom
0
Reply With Quote
      05-26-2011, 10:09 AM   #11
m1bjr
LSD - No, you're not seeing things
 
m1bjr's Avatar
 
Drives: RS250 CUP
Join Date: Mar 2010
Location: Somerset UK

Posts: 3,313
iTrader: (4)

Send a message via MSN to m1bjr
Quote:
Originally Posted by doughboy View Post
It does open after the fast cold idle, but it's used by the DME again on light throttle cruise and at other specified load/throttle points to control noise.

I tried disconnecting mine so it stayed open, it sounds loud at warm up but the boominess at about 80 on light throttle is horrendous. There is increased boom noise at other times too.

Saves BMW having to design a perfect exhaust, just use a flap to get rid of unwanted resonance.
I stand corrected then, never able to notice any effect from mine at all.
Even with it pinned open.
The bastuck makes little more cabin noise at small throttle either.
Thats definately a win-win over the oem then

Who wants to drive a tuned 335i at small throttles though?

__________________
m1bjr is offline   United Kingdom
0
Reply With Quote
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
Forum Jump


All times are GMT -5. The time now is 12:57 PM.




e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
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