brody05

Hi there, I am new to the site (all the way from little ol New Zealand) and have been trying to research air fuel ratio's.

I have had a VCM suite edit and OTRCAI on my LS1 and getting great power but wonder how lean is too lean and what others are running.

On the dyno I am at the peak hitting 13.4:1 - 13.6:1 between 4000rpm and 5500 rpm where it drops back to 13.25:1 up to 6400 rpm.

Sorry if this has come up before but I did a search and didn't find much at all.

Thanks

dynocar

Usually WOT peak power and torque accur somewhere within 12.8-13.2:1 for NA engines. This varies from car to car, dyno to dyno due to different loads and the accuracy of various wide band A/F measuing devices. Sometimes being at the rich side of this spread in the peak torque area and the lean side in the peak HP area helps both, but not always. Hope this helps.

ESR

iTrader: (7)

4800-5200 is high torque it will be more lean there thats is not lean for a n/a motor. its fine there........

WS6FirebirdTA00

iTrader: (33)

i run 13.0-13.4 to be safe, some guy run high 13's to make the extra power.

soundengineer

iTrader: (16)

heres a reference for you

9.0:1 BLACK SMOKE (NO POWER)

11.5:1 RICH BEST TORQUE @ WOT

12.2:1 SAFE BEST POWER @ WOT

13.3:1 LEAN BEST TORQUE @ WOT

14.6:1 STOCHIMETRIC AFR ( CHEMICALLY CORRECT )

15.5:1 LEAN CRUISE

16.5:1 BEST FUEL ECONOMY

18.0:1 CARBURETED LEAN LIMIT

22.0:1 EFI LEAN LIMIT

mostly for an NA mototr you want to shoot for 12.5 down low till you get to peak torque.....you want to then lean out slichtly on your way up to peak HP where you want to hit 12.8, then richen back up to 12.5 by redline...and makie it like 12.0 above redline for some safety dump in fuel....

with FI...just do the same...except 11.5~11.8~11.5~11.0

if you spray and Force air in...you might want to go another half a point richer again

also in general you want to be 2-4* less timing at peak torque than at peak HP.....