Injectors and PE vs RPM
i would think that putting in a larger injector the amount of extra fuel from the PE vs RPM table increase even if your IFR is scaled... since the PEvRPM isnt a scale... just an amount to add.
If you dial in your IFR curve properly, then you shouldn't have to change your PE vs RPM table at all. The PE table is an a/f target value not a scaler.
A/F Target = 14.78 / PE
A/F Target = 14.78 / 1.240
A/F Target = 11.9
The above calc is rarely accurate though on a modded car.
Notice though that certain injectors behave differently at high loads though. As long as you are still using the same offset curve for both injectors, you may notice rich or lean spot popping up in your WOT a/f curve due to the discrepencies with injector offset.
Good Luck
A/F Target = 14.78 / PE
A/F Target = 14.78 / 1.240
A/F Target = 11.9
The above calc is rarely accurate though on a modded car.
Notice though that certain injectors behave differently at high loads though. As long as you are still using the same offset curve for both injectors, you may notice rich or lean spot popping up in your WOT a/f curve due to the discrepencies with injector offset.
Good Luck
Originally Posted by NoGo
If you dial in your IFR curve properly, then you shouldn't have to change your PE vs RPM table at all. The PE table is an a/f target value not a scaler.
A/F Target = 14.78 / PE
A/F Target = 14.78 / 1.240
A/F Target = 11.9
The above calc is rarely accurate though on a modded car.
Notice though that certain injectors behave differently at high loads though. As long as you are still using the same offset curve for both injectors, you may notice rich or lean spot popping up in your WOT a/f curve due to the discrepencies with injector offset.
Good Luck
A/F Target = 14.78 / PE
A/F Target = 14.78 / 1.240
A/F Target = 11.9
The above calc is rarely accurate though on a modded car.
Notice though that certain injectors behave differently at high loads though. As long as you are still using the same offset curve for both injectors, you may notice rich or lean spot popping up in your WOT a/f curve due to the discrepencies with injector offset.
Good Luck
It is true that adding headers usually richens up the mixture up top. I have always attributed this to a reduction in pump losses on the motor, not valve overlap. Reduced pumping losses mean a reduced load on the motor. A reduction in load on the motor means less fuel to make the same power. Being that the PCM is still applying the same amount fuel per RPM, the overal mixture is going to be richer. This is merely my speculation though, I haven't run any tests to verify this.
As I said earlier the PE table equation works well for near stock cars, but it becomes increasingly inaccurate as you mod the car. I am guessing that the open loop fueling is also based off of an expected torque curve programmed into the PCM. Again, more speculation, but I as well as most other tuners can vouch that PE curves can vary greatly from car to car.
-Kevin
As I said earlier the PE table equation works well for near stock cars, but it becomes increasingly inaccurate as you mod the car. I am guessing that the open loop fueling is also based off of an expected torque curve programmed into the PCM. Again, more speculation, but I as well as most other tuners can vouch that PE curves can vary greatly from car to car.
-Kevin
