E90Post
 


 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Looking at all the dynos, can someone please explain...



Reply
 
Thread Tools Search this Thread
      12-19-2006, 10:51 AM   #1
sdiver68
Expert Road Racer
22
Rep
1,330
Posts

 
Drives: 07 335i e90, 09 335i e93
Join Date: Jul 2006
Location: St. Louis, MO

iTrader: (3)

Looking at all the dynos, can someone please explain...

...the torque curve drop-off > ~6K RPM?

It's rather steep, and I can't help but wonder what this car will do with a more normal looking TQ curve at higher RPM's?
Appreciate 0
      12-19-2006, 11:19 AM   #2
shiv@vishnu
Tuner
United_States
702
Rep
17,616
Posts

 
Drives: X1, 335i
Join Date: Sep 2006
Location: SF Bay, CA

iTrader: (0)

Quote:
Originally Posted by sdiver68
...the torque curve drop-off > ~6K RPM?

It's rather steep, and I can't help but wonder what this car will do with a more normal looking TQ curve at higher RPM's?
Turbo engines will always have a bell shaped looking torque curve. Sounds unfortunate until you realize that the bell shape occurs from having having heaps more midrange torque than an equivalently powered naturally aspirated or supercharged powerplant, and not from having less torque above 6000rpm. It's nice to drive a car that makes peak power 1200rpm short of redline

-shiv
Appreciate 0
      12-19-2006, 11:20 AM   #3
ward
Major General
70
Rep
6,162
Posts

 
Drives: F
Join Date: May 2005
Location: T

iTrader: (0)

you just have to shift a bit earlier than the redline

it's actually pretty nice
Appreciate 0
      12-19-2006, 11:52 AM   #4
sdiver68
Expert Road Racer
22
Rep
1,330
Posts

 
Drives: 07 335i e90, 09 335i e93
Join Date: Jul 2006
Location: St. Louis, MO

iTrader: (3)

Quote:
Originally Posted by shiv@vishnu
Turbo engines will always have a bell shaped looking torque curve. Sounds unfortunate until you realize that the bell shape occurs from having having heaps more midrange torque than an equivalently powered naturally aspirated or supercharged powerplant, and not from having less torque above 6000rpm. It's nice to drive a car that makes peak power 1200rpm short of redline

-shiv
I agree that bell shaped is normal, but this seems like more of a lop-sided bell than most I'm used to seeing. Like almost flat from way down low until ~5.8K or so, then steep drop. To your point, though, I AM way more experienced with NA engines than FI. Thanks for the clarification.
Appreciate 0
      12-19-2006, 12:01 PM   #5
hemi to e90
dat boost doe
hemi to e90's Avatar
Poland
17
Rep
1,552
Posts

 
Drives: 10 335i, 12 a8, 14 899, 10 zr1
Join Date: Aug 2005
Location: staten island

iTrader: (1)

please post pic of dyno plot ur referring to
Appreciate 0
      12-19-2006, 12:04 PM   #6
2007/335i/coupe
Falling in Love with German Boost
2007/335i/coupe's Avatar
6
Rep
299
Posts

 
Drives: 335i, E350, Accord EX, GSXR750
Join Date: Dec 2006
Location: California

iTrader: (0)

Garage List
Quote:
Originally Posted by hemi to e90
please post pic of dyno plot ur referring to
Here you go
http://www.e90post.com/forums/showpo...01&postcount=1
Appreciate 0
      12-19-2006, 12:07 PM   #7
hemi to e90
dat boost doe
hemi to e90's Avatar
Poland
17
Rep
1,552
Posts

 
Drives: 10 335i, 12 a8, 14 899, 10 zr1
Join Date: Aug 2005
Location: staten island

iTrader: (1)

Quote:
Originally Posted by 2007/335i/coupe

thanks i wouldnt worry about it. its correct for what it is and the HP picks up nicely to compensate
Appreciate 0
      12-19-2006, 12:26 PM   #8
Bravo1
Private First Class
1
Rep
114
Posts

 
Drives: Accord
Join Date: Sep 2006
Location: Lafayette, LA

iTrader: (0)

Well torque is going to drop after 5252 rpm and horsepower will increase. So there is no need to worry and you can shift all the way into redline if you want... atleast with the xede the hp isn't being reduced, so let her rip.
Appreciate 0
      12-19-2006, 12:47 PM   #9
SteveMD
Colonel
SteveMD's Avatar
United_States
48
Rep
2,431
Posts

 
Drives: '12 X5 50i, '11 GTI DSG
Join Date: Dec 2005
Location: Raventown!

iTrader: (3)

Garage List
2012 X5 50i  [0.00]
Quote:
Originally Posted by Bravo1
Well torque is going to drop after 5252 rpm and horsepower will increase. So there is no need to worry and you can shift all the way into redline if you want... atleast with the xede the hp isn't being reduced, so let her rip.
While I know what you're trying to say, there's no relationship between torque and 5252 RPM. Torque could easily increase after 5252 RPM. Maybe not on this engine but certainly possible on others.

At 5252 RPM torque and HP will have the same numerical value. Above 5252, HP will ALWAYS be greater than torque and below 5252 HP will always be less. No exceptions.

However there is no law or formula to stop an engine making more torque at say 5500 RPM than it does at 5252. A Formula 1 engine for example has it's peak torque around 10000 RPM.
__________________
2006 E90 330i (retired)
2009 E90 335i (retired)
2012 E70 X5 50i M Sport, JB Stage 1, 4.6 secs 0-60.
2011 VW GTI/DSG
Appreciate 0
      12-19-2006, 02:06 PM   #10
shingles
New Member
0
Rep
22
Posts

 
Drives: Acura
Join Date: Jun 2006
Location: Houston, TX

iTrader: (0)

Manufacturers will sometimes artifically tune the car so that it makes less power on the top end than is actually possible. This is to protect the engines...

A question regarding XEDE here - how does Xede adjust boost in the car? is it a constant % above factory, or do you aim to hit a target number? Assuming the factory tune drops boost on the top end, can Xede be programmed to compensate?

thx,
-S
Appreciate 0
      12-19-2006, 02:30 PM   #11
Insider
Captain
Insider's Avatar
8
Rep
710
Posts

 
Drives: 2007 335i
Join Date: Jul 2006
Location: 4,500 feet above sea level

iTrader: (0)

Quote:
Originally Posted by SteveMD
While I know what you're trying to say, there's no relationship between torque and 5252 RPM. Torque could easily increase after 5252 RPM. Maybe not on this engine but certainly possible on others.

At 5252 RPM torque and HP will have the same numerical value. Above 5252, HP will ALWAYS be greater than torque and below 5252 HP will always be less. No exceptions.

However there is no law or formula to stop an engine making more torque at say 5500 RPM than it does at 5252. A Formula 1 engine for example has it's peak torque around 10000 RPM.
Or the new M5. Which has peak torque at 6,200 I believe.
Appreciate 0
      12-19-2006, 02:53 PM   #12
teknochild
Your resident 4um troll
teknochild's Avatar
37
Rep
2,021
Posts

 
Drives: 335 coupe
Join Date: Dec 2006
Location: fl

iTrader: (0)

are you asking WHY the torque drops off so much compared to NA cars or what>?
Appreciate 0
      12-19-2006, 03:03 PM   #13
sdiver68
Expert Road Racer
22
Rep
1,330
Posts

 
Drives: 07 335i e90, 09 335i e93
Join Date: Jul 2006
Location: St. Louis, MO

iTrader: (3)

Quote:
Originally Posted by teknochild
are you asking WHY the torque drops off so much compared to NA cars or what>?
I'm asking why the TQ curve looks so strange and drops so suddenly. Shiv said it was because of FI. I think there are gains to be made in reshaping the curve, but Shiv does that for a living and I'm just a racer so take my opinion fwiw, which in engineering is not even $.02!
Appreciate 0
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 08:52 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