Best Turbo AFR and timing for launch control?

[ALLR1SE]

Just curious what others run for AFR on there two step/launch control? Also what timing are you running and how much boost do you build?

I am at 15-17 AFR with 19* timing at 4300 rpm at 105 kpa. Idk if this is good or if it can get better. I run 18lbs of boost at the track on E85, my WB isnt setup for ethanol so it still reads gas AFR.

[07GTS]

u need more fuel by the looks your WB is way leaner then your EQratio commanded ur WB should be around 11.5 AFR to match commanded, also its easier to use lambda then with a scaled tune and ethanol u dont have to worry about calculations it just works all the time

[GHuggins]

Lambda and air fuel are all the same thing - 15 to 17 afr is WAY lean... 07GTS stated it clearly - if commanding 11.5 - should be doing something very close to this... You can use lambda error or air fuel error to correct... I posted the math parameter for air fuel error if you prefer to use that - even though it's the same as lambda error - in the scanner section on here... It's titled air fuel error for changing stoichiometric and alcohol or something like that? This is all of course if your not talking about the two step cutting fuel throwing your air fuel ratio off? I honestly didn't look at the log...

[tbrtuning]

Haven't done it on a GM so not sure if you can use the Launch Spark to do this or not but on an Evo running rich with retarded timing will generate a lot more boost. EGTs and manifold pressure will rise and the increased pressure will help spool the turbo.

[Area47]

keep in mind, the two step if used as a timing cut, or spark control may show lean on the wb due to the fuel mass going past it.

[tbrtuning]

Good point I forgot to mention. By retarding timing you are creating a misfire and raw fuel is dumped into the exhaust. The wideband will read lean when this happens. This isn't really the kind of thing where you're tuning for a specific AFR or anything you just need to make changes in the right direction until you get your desired results or see no more progress in the desired direction at launch.

[dreksnot]

My 2-step cuts timing (does not retard). As soon as load is put on the motor, AFR goes happily to commanded. I always presumed it was the excess fuel in the system and spark cut that made for the wonky WB reading.
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[tbrtuning]

I guess my saying retarded timing was not good wording. I meant retarded from the normal point of spark advance not necessarily less than 0. It just depends how far you take it if you will start getting bad misfires and raw fuel dumping in the exhaust causing a lean reading. Pull enough out and it will happen.