E90Post
 


TireRack
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Optimum AFR for DI?



Reply
 
Thread Tools Search this Thread
      01-15-2008, 07:16 PM   #23
BzzzBom
Major
 
Drives: 05 R53 MINI / 09 335i Coupe
Join Date: Jul 2006
Location: Los Angeles

Posts: 1,214
iTrader: (0)

Quote:
Originally Posted by shiv@vishnu View Post
I think Malekreza11 hit it right on the head. There is really no reason to run a DI engine as rich as a convention engine. Just a waste of gas.

The usual knock tendency you see crop up with running a conventional moderately boost non-DI turbo engine in the 13-13.5:1 range does happy with the N54 engine. In fact, you can almost run it on either side of stoich and not see much difference in power or allowable advance. It's pretty neat.

Shiv
Doesn't this mean that piggybacks that control boost only are all that is needed for moderate levels (11-13 PSI) of peak boost? I have never seen one reported SES or CEL reported with the SSTT or JB1 and both products keep the AFR under 13 at higher rpms. How much boost can safely be run using the stock AFR maps (i.e., intercepting the TMAP sensor only)
BzzzBom is offline  
0
Reply With Quote
      01-15-2008, 07:59 PM   #24
BzzzBom
Major
 
Drives: 05 R53 MINI / 09 335i Coupe
Join Date: Jul 2006
Location: Los Angeles

Posts: 1,214
iTrader: (0)

Quote:
Originally Posted by shiv@vishnu View Post
I think Malekreza11 hit it right on the head. There is really no reason to run a DI engine as rich as a convention engine. Just a waste of gas.

The usual knock tendency you see crop up with running a conventional moderately boost non-DI turbo engine in the 13-13.5:1 range does happy with the N54 engine. In fact, you can almost run it on either side of stoich and not see much difference in power or allowable advance. It's pretty neat.

Shiv
Is this consistent with the post listed below from March 2007?

Without adjustments to fuel and timing, that 2-3psi bump in power is going to dig right into the margin of safety that BMW left in the tuning. Really not a good idea in my opinion. Especially for a car that runs so lean from the factory. But what you are proposing is easy to do. All you need to do is isolate the signal wire in the MAP sensor (simple 0-5v) and attenuate the signal a bit (perhaps 10%).

-shiv
BzzzBom is offline  
0
Reply With Quote
      01-15-2008, 08:32 PM   #25
shiv@vishnu
Tuner
 
Drives: X1, 335i
Join Date: Sep 2006
Location: SF Bay, CA

Posts: 17,616
iTrader: (0)

Quote:
Originally Posted by BzzzBom View Post
Is this consistent with the post listed below from March 2007?

Without adjustments to fuel and timing, that 2-3psi bump in power is going to dig right into the margin of safety that BMW left in the tuning. Really not a good idea in my opinion. Especially for a car that runs so lean from the factory. But what you are proposing is easy to do. All you need to do is isolate the signal wire in the MAP sensor (simple 0-5v) and attenuate the signal a bit (perhaps 10%).

-shiv
It's pretty consistent. Timing adjustments was/is the biggest contributor to knock threshold. Fueling is a small contributor once it steps out side a certain range. But with DI, that range is surprisingly wide and lean, as discussed in this thread.

Shiv
shiv@vishnu is offline   United_States
0
Reply With Quote
      01-16-2008, 09:57 PM   #26
Max@Logic
 
Max@Logic's Avatar
 
Drives: E55 AMG
Join Date: Oct 2007
Location: Irvine

Posts: 426
iTrader: (3)

A/F is for thermal management. Contrary to what people might believe, It really has no big effect on hp. DI has a cooling advantage over port type injection. Thus allowing for a more leaner mixture.. Cleaner burn and better gas mileage. Ignition timing is where you make the power. Hope this helps.


All the Best,
Max
Max@Logic is offline   United_States
0
Reply With Quote
      01-17-2008, 08:16 PM   #27
dadasracecar
Banned
 
Drives: '06 Mazdaspeed6
Join Date: Jan 2008
Location: DC

Posts: 268
iTrader: (0)

Quote:
Originally Posted by Max@Logic View Post
A/F is for thermal management. Contrary to what people might believe, It really has no big effect on hp. DI has a cooling advantage over port type injection. Thus allowing for a more leaner mixture.. Cleaner burn and better gas mileage. Ignition timing is where you make the power. Hope this helps.

All the Best,
Max
It very much does. Thank you.
dadasracecar is offline  
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 10:28 AM.




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