Notices
Tuning, Diagnostics, Electronics, and Wiring HP Tuners | EFILive | Hand Held Programmers | Stand Alone PCM's | Electronics | Wiring Diagrams

AFR clarrification!

Thread Tools
 
Search this Thread
 
Old 09-09-2008, 04:37 PM
  #1  
GFYS and STFU
Thread Starter
iTrader: (8)
 
Spoolin's Avatar
 
Join Date: Jan 2007
Location: Here and sometimes there too.
Posts: 13,870
Received 4 Likes on 4 Posts
Question AFR clarrification!

Sooo...Need some clarification on something.
I read that it's been found that somewhere between 13.2:1 and 13.4:1 is an ideal AFR for best power. However I'm under the impression that between 11.5:1 and 12.5:1 is the sweet spot of us!
Are there different ideal AFR's between N/A and F/I set-ups?
Old 09-09-2008, 04:51 PM
  #2  
2nd fastest 5.3 ECSB
iTrader: (14)
 
trever1t's Avatar
 
Join Date: Oct 2005
Location: NorCal
Posts: 26,690
Likes: 0
Received 1 Like on 1 Post
Default

Yea, afr for NA can be a bit leaner.....I wouldn't want to run leaner than 11.9 FI
Old 09-09-2008, 04:56 PM
  #3  
GFYS and STFU
Thread Starter
iTrader: (8)
 
Spoolin's Avatar
 
Join Date: Jan 2007
Location: Here and sometimes there too.
Posts: 13,870
Received 4 Likes on 4 Posts
Default

Onset of knock is too great on FI?
Old 09-09-2008, 05:02 PM
  #4  
2nd fastest 5.3 ECSB
iTrader: (14)
 
trever1t's Avatar
 
Join Date: Oct 2005
Location: NorCal
Posts: 26,690
Likes: 0
Received 1 Like on 1 Post
Default

heat! Lots of heat FI, fuel helps to cool. Correct me if I'm wrong?
Old 09-09-2008, 05:32 PM
  #5  
TECH Fanatic
iTrader: (17)
 
sickREDsierra's Avatar
 
Join Date: Dec 2007
Location: Mobile, AL
Posts: 1,424
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by Spoolin
Sooo...Need some clarification on something.
I read that it's been found that somewhere between 13.2:1 and 13.4:1 is an ideal AFR for best power. However I'm under the impression that between 11.5:1 and 12.5:1 is the sweet spot of us!
Are there different ideal AFR's between N/A and F/I set-ups?
are you serious? all that **** done to your truck and you just read that FI has different AFR... i am dissapointed.

generally, n/a like to be around 12.6-12.8 for best power. nitrous should be a little richer, low 12's is what i run.

for FI, you run much richer than n/a, some run low 11's AFR, depends on amount of boost/timing/octane of gas and if meth will be used.

i think most FI guys are around mid-high 11's AFR at WOT.

your cruise, however, should be around 14.7-ish (stoich) although i wonder if i can go leaner than that at cruise and pick up any gas mileage.

Last edited by sickREDsierra; 09-09-2008 at 05:49 PM.
Old 09-09-2008, 05:41 PM
  #6  
Truck Sponsor
iTrader: (12)
 
Wheatley's Avatar
 
Join Date: Apr 2003
Location: Sealy/Katy TX
Posts: 3,286
Likes: 0
Received 2 Likes on 2 Posts
Default

12.5-12.8 A/F N/A and I like about 11.7-11.9 FI
Old 09-09-2008, 05:41 PM
  #7  
Admin
iTrader: (22)
 
03sierraslt's Avatar
 
Join Date: Jul 2004
Location: Western PA
Posts: 19,004
Received 217 Likes on 173 Posts
Default

Spoolin for the boost level that you are running I would run like 11.3 to 11.5 to be on the safe side. I run mine at about 11.6 but I am not running 16+ psi either.
Old 09-09-2008, 06:08 PM
  #8  
GFYS and STFU
Thread Starter
iTrader: (8)
 
Spoolin's Avatar
 
Join Date: Jan 2007
Location: Here and sometimes there too.
Posts: 13,870
Received 4 Likes on 4 Posts
Default

Originally Posted by sickREDsierra
are you serious? all that **** done to your truck and you just read that FI has different AFR... i am dissapointed.

generally, n/a like to be around 12.6-12.8 for best power. nitrous should be a little richer, low 12's is what i run.

for FI, you run much richer than n/a, some run low 11's AFR, depends on amount of boost/timing/octane of gas and if meth will be used.

i think most FI guys are around mid-high 11's AFR at WOT.

your cruise, however, should be around 14.7-ish (stoich) although i wonder if i can go leaner than that at cruise and pick up any gas mileage.
Using the Lambda scale best power output has been found to be λ = 0.95 (between 13.2 and 13.4:1 AFR)
For best economy you swing to the other side of stoichiometric balance with a target of λ = 1.05 (about 15.5:1 AFR)
Old 09-09-2008, 06:15 PM
  #9  
TECH Junkie
iTrader: (10)
 
charcold-bowtie's Avatar
 
Join Date: Jul 2006
Location: Midland Texas
Posts: 3,198
Likes: 0
Received 0 Likes on 0 Posts
Default

lambda is another confusing coversion, dont worry about it lol. I mean the conversion is easy, but im not used to it and I prefer AFR.

Looking at my tune, I command around 11.5 AFR WOT from 3500 and up RPM.
My lean cruise is commanding 15.3 AFR. Some of the efilive forum guys are commanding 16+ during lean cruise. watch timing in this discussion as well.
Old 09-09-2008, 06:18 PM
  #10  
GFYS and STFU
Thread Starter
iTrader: (8)
 
Spoolin's Avatar
 
Join Date: Jan 2007
Location: Here and sometimes there too.
Posts: 13,870
Received 4 Likes on 4 Posts
Default

Originally Posted by 03sierraslt
Spoolin for the boost level that you are running I would run like 11.3 to 11.5 to be on the safe side. I run mine at about 11.6 but I am not running 16+ psi either.
I have to recalibrate my wideband since it was installed before the turbo. Widebands are rated to operate between 0.8 bar and 1.3 bar to be reasonably accurate. Because mine routinely see's up to 4 bar with it's location the sensor reads furthur from stoich. So when I'm rich it reads richer than what it is and when I'm running lean it reads leaner than it actually is.
At WOT I'm seeing between 9.6:1 and 10.2:1. I think right now I'm in the high 10's/low 11's...but not sure.


Quick Reply: AFR clarrification!



All times are GMT -5. The time now is 02:26 AM.