alrajhi

hello guys
i have tuned a 2003 holdn ls1 engine after tunning the a/r ratio with EFI LIVE the a/r ratio is 13.3-13.6 at wot what do you think guys the engine made 306 whp (we are using 95 octane pump gas)?

SSpdDmon

iTrader: (10)

too lean imo...try 12.8-13.0 at peak power.

alrajhi

thank you man ,one thing i forgot to mention the dyno wideband was hooked at the exhust tip and the car has catolic converter,would that effect the reading.

Rob

iTrader: (6)

Then you should be pretty close. Maybe just a touch too lean. You need to ask the dyno guys what they have seen with tailpipe placement vs. collector placement. Could be anywhere from .3 to .6 difference.

Alvin

iTrader: (2)

The perfect AFR is exactly 12.984245

Joking..

Why does everyone look for one specific number? See what works best for your particular motor. Thats what dyno tuning is for.. not to punch in a AFR number and a timing number everyone else runs.

soundengineer

iTrader: (16)

anywhere from 12.5~ 13.4 dependent on a lot of things....
you have to play with it on the dyno to findout what your cars ideal AFR is at all rpm's

and it will not be the same at 4000 rpm as it will be at 5200 or at 6000 or at 6400
it should not be a flat value for max power

Billf6531

Interesting thread.

Most people advocate a flat PE / afr. Soundengineer is probably correct that a non-linear WOT afr will give a better result. It only makes sense that the low rpm range needs a leaner afr, as does peak torque.

Sound, can you post what you consider to be a good non-linear set of PE values so that this fellow can scale them up or down to meet his needs?

brad8266

iTrader: (23)

LS1's seem to all have their own AFR that they like best and make the most power at. Non linerar is the best way to go though.

soundengineer

iTrader: (16)

usualy its a little leaner down low..like from 800-2000ish rpms
then its Rich at peak Torque and leaner at peak HP and then richer again at Redline/revlimiter

a good example would be something like

1.12988 1.12988 1.12988 1.12988 1.12988 1.12988 1.14355 1.15625 1.16992 1.16992 1.16992 1.16992 1.16992 1.15918 1.14844 1.16992 1.16992 1.16992 1.16992

basically 13.0 low...12.5 by peak torque, 12.8 by peak HP, and back to 12.5 at revlimiter
this is on my car...with stock cam and a few boltons

12secSS

iTrader: (30)

Just an FYI ... if you look at AFR Spark Correction Table GM provides, it clearly mimick's what Scott is saying. They add more spark in the same respective areas being recommended. Kind of tells you something doesn't?

soundengineer

iTrader: (16)

exactly