For anyone who tunes their 92-93 speed density LT1, what does your %Change to A/F ratio vs. RPM look like? Going by the formula in the help, which I understand prob isn't close at all, it shows a PE A/F ratio of almost 19:1. Just wondering how your graph looks after being tuned.

 

It depends on too much for you to get much info from what others have done for their tunes.
My buddies 396 was 12.3:1 on the wideband and I think the pe vs. rpm was increaseing from 5 to 7 as rpm increases. This was with a Lucas 42lb injector and a constant of 42.5.

 

This is how my stock table looks:

RPM %Change

400 - 11.7
800 - 11.7
1200 - 11.7
1600 - 11.7
2000 - 41.4
2400 - 35.9
2800 - (-17.2)
3200 - (-29.7)
3600 - (-14.1)
4000 - (-1.6)
4500 - (-6.3)
5000 - 4.7
5500 - (-6.3)
6000 - (-8.6)
6500 - 7.0
7000 - 3.9
7500 - 7.8

Why is there such a drastic change in numbers while in reality, the change in fueling is more linear. Any thoughts?

 

The numbers aren't derived from a formula. They are empirical numbers derived from real world measurements. Data trumps theory everytime. Why do you say "in reality, the change in fueling is more linear"?. I am not sure what you mean by this.

Rich Krause

 

The formula I was refering to was in the tunercat help file:
"The resulting air / fuel ratio can be calculated as follows:

PE AFR = 14.7 / (1 + %Change vs Cool/100 + %Change vs RPM/100)"

My comment did come out bad. Assuming the VE tables are dead on, I figured the amount of fuel added in PE mode should be close at all RPM, where as the stock table is indicating that there is a drastic change in the amount of fuel delivered at 2400rpm compared to 400rpm higher. Is my thinking correct?