PLANT PROTECTION
07-11-2003, 12:29 PM
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.
Dan K
07-12-2003, 12:20 AM
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.
PLANT PROTECTION
07-12-2003, 09:56 PM
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?
rskrause
07-13-2003, 11:39 AM
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
PLANT PROTECTION
07-13-2003, 02:36 PM
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?