BMW M3 Forum (E90 E92)

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


Go Back   M3Post - BMW M3 Forum > E90/E92 M3 Technical Topics > Engine, Transmission, Exhaust, Drivetrain, ECU Software Modifications
 
Post Reply
 
Thread Tools Search this Thread
      12-06-2009, 11:33 AM   #1
ahtim
Akrapovic HK
9

 
Drives: mostly NA, sometimes turbo
Join Date: Oct 2008
Location: Hong Kong,


Posts: 219
iTrader: (0)

M3 in full straight pipe

Hi guys, i am planning to make an unique exhasut for M3, but i really want you guys's advice and see wht you guys think.

i am planning to make a Titian Full Straight pipe from header to the rear tips.
which will include the little thing that u connect between the pipe and the sensor.which will trick the car's computer. so u dun get engine light.
i will also include all the welding and holding point, so basically i will make it the same as all aftermaket exhasut, so it will be a plug and play.


the actual product, i am planning is to be an H pipe for the front, same as AKRA, X pipe in the middle, then straight to rear tips.

anyway, i have some concern.
1. as there is no back pressure, will the torque be even lower?(could this problem be slove by making the middle section or the X pipe thinner, to keep the back pressure?
2. will there be a fire at the back when shift up, or throttle release.


thanks so much
any comment or advice will be welcome.
Appreciate 0
      12-06-2009, 11:38 AM   #2
!Xoible
Banned
United_States
548

 
Drives: ....
Join Date: Nov 2006
Location: .


Posts: 46,037
iTrader: (4)

Garage List
2008 M3  [3.50]
2007 335i  [4.50]
2008 528i  [4.00]
2006 Infiniti - G35 ...  [4.00]
blue_summer did that and lost a lot of power, got rid of it
Appreciate 0
      12-06-2009, 11:41 AM   #3
ahtim
Akrapovic HK
9

 
Drives: mostly NA, sometimes turbo
Join Date: Oct 2008
Location: Hong Kong,


Posts: 219
iTrader: (0)

hi, i have ty to searh, but there isnt a memebr call BLUE_summer
Appreciate 0
      12-06-2009, 04:56 PM   #4
Edman951
Second Lieutenant
Canada
10

 
Edman951's Avatar
 
Drives: F10 550xi, Alpine white
Join Date: Nov 2006
Location: Montreal, Quebec


Posts: 285
iTrader: (1)

I have a catless x-pipe with 4 resonators. (borla x-pipe) and tried it without the factory exhaust. With the rear section removed it felt like the car was slow to rev. Actually have a video too.

But after trying the car with and without the stock mufflers
The car is faster with Borla x-pipe and the stock muffler then without the muffler.
Appreciate 0
      12-06-2009, 05:02 PM   #5
Checkcaptain
Captain
Germany
39

 
Drives: BMW M3 E92
Join Date: Jan 2009
Location: Germany


Posts: 995
iTrader: (0)

Send a message via MSN to Checkcaptain Send a message via Skype™ to Checkcaptain
Will,

like I answered in your mail already - this makes no sense!



Quote:
Originally Posted by ahtim View Post
Hi guys, i am planning to make an unique exhasut for M3, but i really want you guys's advice and see wht you guys think.

i am planning to make a Titian Full Straight pipe from header to the rear tips.
which will include the little thing that u connect between the pipe and the sensor.which will trick the car's computer. so u dun get engine light.
i will also include all the welding and holding point, so basically i will make it the same as all aftermaket exhasut, so it will be a plug and play.


the actual product, i am planning is to be an H pipe for the front, same as AKRA, X pipe in the middle, then straight to rear tips.

anyway, i have some concern.
1. as there is no back pressure, will the torque be even lower?(could this problem be slove by making the middle section or the X pipe thinner, to keep the back pressure?
2. will there be a fire at the back when shift up, or throttle release.


thanks so much
any comment or advice will be welcome.
Appreciate 0
      12-06-2009, 05:06 PM   #6
!Xoible
Banned
United_States
548

 
Drives: ....
Join Date: Nov 2006
Location: .


Posts: 46,037
iTrader: (4)

Garage List
2008 M3  [3.50]
2007 335i  [4.50]
2008 528i  [4.00]
2006 Infiniti - G35 ...  [4.00]
Quote:
Originally Posted by ahtim View Post
hi, i have ty to searh, but there isnt a memebr call BLUE_summer
i apologize bluesummer...
Appreciate 0
      12-06-2009, 06:40 PM   #7
swamp2
Lieutenant General
United_States
213

 
swamp2's Avatar
 
Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA


Posts: 10,201
iTrader: (1)

Quote:
Originally Posted by PencilGeek View Post
Look at this dyno chart very carefully. Look at the blue "torque" line for the stroker motor between 2500-3800 RPMs. This is what can happen when the exhaust doesn't have the correct back pressure. http://bmw.pencilgeek.org/showDyno.html?recID=1

ECU tuning couldn't fix it. It was fixed by slightly redesigning the exhaust components. This is what it looks like now:
http://bmw.pencilgeek.org/showDyno.html?recID=114
Wow that is dramatic. Can you exand on the cause/effect and fix with more detail. Very interesting. Nice work.
Appreciate 0
      12-06-2009, 06:52 PM   #8
ahtim
Akrapovic HK
9

 
Drives: mostly NA, sometimes turbo
Join Date: Oct 2008
Location: Hong Kong,


Posts: 219
iTrader: (0)

thanks to all of you guys!!!

i already know that problem, with the no backpressure, the torque will be reduce.
but does anyone think this problem can be slove by making the middle section smaller or thinner?
Appreciate 0
      12-07-2009, 08:12 AM   #9
mixja
Captain
United_States
19

 
Drives: 2011 E90 DCT Silverstone
Join Date: Jun 2008
Location: Beverly Hils, CA


Posts: 783
iTrader: (1)

Quote:
Originally Posted by PencilGeek View Post
Look at this dyno chart very carefully. Look at the blue "torque" line for the stroker motor between 2500-3800 RPMs. This is what can happen when the exhaust doesn't have the correct back pressure. http://bmw.pencilgeek.org/showDyno.html?recID=1

ECU tuning couldn't fix it. It was fixed by slightly redesigning the exhaust components. This is what it looks like now:
http://bmw.pencilgeek.org/showDyno.html?recID=114
What is your current exhaust setup?
Appreciate 0
      12-07-2009, 08:16 AM   #10
mixja
Captain
United_States
19

 
Drives: 2011 E90 DCT Silverstone
Join Date: Jun 2008
Location: Beverly Hils, CA


Posts: 783
iTrader: (1)

Quote:
Originally Posted by ahtim View Post
thanks to all of you guys!!!

i already know that problem, with the no backpressure, the torque will be reduce.
but does anyone think this problem can be slove by making the middle section smaller or thinner?
Back pressure is likely not the issue, although it could have an impact on the factory valve timing settings (i.e. cause over scavenging).

Exhaust gas speed is more likely the issue - the stock exhaust system has strange narrowings in strange places which I think are there on purpose to facilitate high exhaust gas speeds.

I'm hoping a primary cat delete is the right modification to get optimal exhaust flow without affecting low end torque...
Appreciate 0
      12-07-2009, 08:37 AM   #11
Kyoshi71
Colonel
35

 
Kyoshi71's Avatar
 
Drives: 2010 M3 Coupe
Join Date: Jul 2006
Location: New York


Posts: 2,528
iTrader: (0)

Dude, just buy a full exhaust system and stop screwing around. Very rarely, if ever, have I seen a street car run better with strait pipes. Back pressure is needed; just not as much as stock exhaust.
Appreciate 0
      12-07-2009, 09:03 AM   #12
ahtim
Akrapovic HK
9

 
Drives: mostly NA, sometimes turbo
Join Date: Oct 2008
Location: Hong Kong,


Posts: 219
iTrader: (0)

Quote:
Originally Posted by mixja View Post
What is your current exhaust setup?
i have the full akra from RALF!!!

but i still really want to try this out and see if it work, and wht sound will t be like( mostly for fun)
Appreciate 0
      12-07-2009, 09:19 AM   #13
Eugene-TAIWAN
Brigadier General
Taiwan
79

 
Eugene-TAIWAN's Avatar
 
Drives: E92 M3 Coupe
Join Date: Jun 2009
Location: Taiwan


Posts: 3,112
iTrader: (4)

Quote:
Originally Posted by ahtim View Post
i have the full akra from RALF!!!

but i still really want to try this out and see if it work, and wht sound will t be like( mostly for fun)
you will need a really good file for your car. Or else like they said you will lose power especially on the low end.
__________________

Past: Gintani stage3 M3
present: Porsche 993RWB, 964RS America,996 cupcar, 964 turbo 3.6, 991C4S, i3 in September
Appreciate 0
      12-08-2009, 10:30 AM   #14
gasterus
Private First Class
1

 
gasterus's Avatar
 
Drives: M6
Join Date: Apr 2009
Location: Indonesia


Posts: 185
iTrader: (0)

Quote:
Originally Posted by PencilGeek View Post
Look at this dyno chart very carefully. Look at the blue "torque" line for the stroker motor between 2500-3800 RPMs. This is what can happen when the exhaust doesn't have the correct back pressure. http://bmw.pencilgeek.org/showDyno.html?recID=1

ECU tuning couldn't fix it. It was fixed by slightly redesigning the exhaust components. This is what it looks like now:
http://bmw.pencilgeek.org/showDyno.html?recID=114
PG, which part of the exhaust has been redesign to achieve such an improvement in the torque???
__________________
07 M6 blk/blk, Racing Dynamics RS58 stroker with custom ECU tune, Primary cat bypassed+Akrapovic Evolution exhaust, BMC air filters, RPI air scoops, H&R springs, Dinan FRC & rear sway bar, 20" AC Schnitzer V

08 E92 M3 sparkling graphite/red, Competition pack, Innotech exhaust
Appreciate 0
      12-10-2009, 12:20 PM   #15
BMRLVR
Grease Monkey
Canada
39

 
BMRLVR's Avatar
 
Drives: 2011 E90 M3,1994 Euro E36 M3/4
Join Date: Apr 2006
Location: Fort McMurray, Alberta, Canada


Posts: 2,331
iTrader: (3)

Quote:
Originally Posted by gasterus View Post
PG, which part of the exhaust has been redesign to achieve such an improvement in the torque???
It appears from his list of mods on the dyno runs that there was a change from the original Tri-Y Headers with 40MM Primaries to a 4 into 1 header with 40MM Primaries.
__________________
2011 E90 M3 ZCP - Individual Moonstone/Individual Amarone Extended/Individual Piano Black With Inlay:LINK!!!
1994 Euro E36 M3 Sedan - Daytona Violet/Mulberry:LINK!!!
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
Forum Jump


All times are GMT -5. The time now is 07:15 PM.




m3post
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