new engine tuning

[sanderson231]

If you want to tweak the PE air fuel ratio in search of more power then you will need to invest in a wide band O2 sensor (really an air fuel ratio sensor) otherwise you are flying blind.

[Fast355]

You don't want to go anywhere close to 14.7:1. If you did run there at WOT there will probably be knock and the best case scenario is that the knock sensor would detects it and the PCM would pulls timing. The worst case scenario is engine damage.

During PE you need excess fuel to ensure that all the oxygen in the mixture is consumed. Otherwise you leave power on the table. Excess fuel also protects the engine. Your new engine is not a big step-out from the 350 that is in the car. GM spent countless hours on the dyno developing the power enrichment and spark timing value that are in the calibration. There is little reason for change. Keep it simple. Change the displacement per cylinder from 711 to 784. Change the fuel injector flow rate to match what ever fuel injector are installed.

The OE GM tune on 350 ran up to 60 seconds at WOT before PE enabled. Most of the 0411/P59 truck calibrations are set that way. Timing map is backed off a bit until PE enables then GM puts timing into them. I enabled my PE alot sooner because I wanted more power but it was a fuel saving measure for trucks towing heavy trailers.

[sanderson231]

I looked at the AXCN calibration for a 91 vette. There is no parameter related to PE delay. It looks like PE is enabled with TPS greater than 70.3 %. It does look like the AFR is very rich in PE mode.