Welcome to the North American Subaru Impreza Owners Club Friday April 18, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Engine Management & Tuning

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 01-06-2005, 02:47 AM   #1
casualsurfer
Scooby Specialist
 
Member#: 60773
Join Date: Apr 2004
Location: Indianapolis, IN
Vehicle:
2004 WRX
Silver

Default Is there an ideal A/F ratio for ALL RPM range?

I was just wondering if there was an ideal A/F ratio throughout the RPM range or it depends on what RPM you're running. If it depends, anyone have any idea what that would be in 100RPM increments?
* Registered users of the site do not see these ads.
casualsurfer is offline   Reply With Quote
Old 01-06-2005, 07:29 AM   #2
happasaiyan
Scooby Specialist
 
Member#: 37731
Join Date: Jun 2003
Chapter/Region: MWSOC
Location: Rolling Meadows, IL
Vehicle:
'07 TL-S 6MT
'07 RDX-T

Default

no.

there is an ideal AFR CURVE for a particular engine setup...outside of that, the AFRs vary between load sites, amount of boost, rpm, TPS, etc.

look up micks tuning guide or download turboxs' manual for the utec. thats a good place to start.
happasaiyan is offline   Reply With Quote
Old 01-06-2005, 09:55 AM   #3
hippy
Scooby Specialist
 
Member#: 36528
Join Date: May 2003
Location: florida
Vehicle:
2002 Impreza Wrx
Silver

Default

Bosche seems to think that most engines make most power between 12.5 and 14 to 1 a/f ratio(on gas)...... If an engine's running richer then 12.5 to 1, ya know that more power could probably be made by leaning the a/f ratio out to 12.5 to 1. The problem is that many(if not most of us) of us can't do that for one reason or another(like being octane limited or whatever)), and we're stuck with a/f ratios which are richer then what's ideal.

peace

Last edited by hippy; 01-06-2005 at 10:32 AM.
hippy is offline   Reply With Quote
Old 01-06-2005, 10:17 AM   #4
mbiker97
Scooby Guru
 
Member#: 7922
Join Date: Jun 2001
Chapter/Region: MWSOC
Location: Tucson
Vehicle:
04 CTS-V b/b/b
99 GMC Highrider

Default

Quote:
Originally Posted by casualsurfer
I was just wondering if there was an ideal A/F ratio throughout the RPM range or it depends on what RPM you're running. If it depends, anyone have any idea what that would be in 100RPM increments?
It's really boost or no boost not rpm.
mbiker97 is offline   Reply With Quote
Old 01-06-2005, 11:23 AM   #5
RiftsWRX
Scooby Guru
 
Member#: 6124
Join Date: Apr 2001
Chapter/Region: MWSOC
Location: Glendale Hts, IL, USA
Vehicle:
2000 NFR AP1 S2000
'07 Honda FIT sport (5MT)

Default

At zero load, or minimal load (I.E. cruising) you'd probobly want to maintain stoichimetric for the majority of the RPM range, with an enrichment >4k for example.

As load changes, an ideal AFR range will change, through out the RPM range.

So if you HAD to have one solid AFR from 1-7k rpm, I'd say it have to be done 3 dimensionally

AFRxRPMxLOAD.

That's about the only way you'd safely get away with it.

Jorge (RiftsWRX)
www.ProjectWRX.com
RiftsWRX is offline   Reply With Quote
Old 01-06-2005, 04:44 PM   #6
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

deja vu, all over again

This covers the basics pretty well. The guy is probably a member of NASIOC. Figure 3.8 is the classic AFR figure:
http://www.hss.cmu.edu/philosophy/pr...ang_thesis.pdf

This deals more with timing and what MBT really means, excellent paper:
http://www.visteon.com/utils/whitepa...03_01_3266.pdf

Another good AFR/Timing read is here. It also has some fundamental links. I believe this piece was written by NASIOC member SaabTuner:
http://www.saabscene.co.uk/ubb/ultim...c/23/1194.html
bboy is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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

Similar Threads
Thread Thread Starter Forum Replies Last Post
loud knock from block, all rpm range, all the time. Quix Service & Maintenance 6 07-16-2007 08:08 PM
Ok so i have everything to tune with, what is an ideal A/F ratio? GregBolby Engine Management & Tuning 6 03-07-2005 11:01 PM
what is an ideal air fuel mixture for a WRX? Homemade WRX Engine Management & Tuning 58 03-23-2004 09:59 PM
Is there an agreed upon best replacement for re92s? Rev Tire & Wheel 4 10-05-2003 09:16 PM
Where is/ or is there an idle adjustment screw for 02' Wrx? PaulRex Factory 2.0L Turbo Powertrain 5 02-14-2003 06:19 PM


All times are GMT -4. The time now is 12:01 AM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.