Thanks Ron & @wetwe33. I'll have to dig in to understand why and implications. Appreciate the feedback.
Copy/pasted from a previous explanation so you won’t have all the context but this may get you started...
Here is a basic calculation of the airflow mass:
Datapoint of peak mass airflow to closest 500 rpm
Basically, if I didn’t take any air/fuel out of the equation at 6500rpm and 26.25 psi of boost = 40.94 psia = 83.35 inhg.
Equation for airflow mass per event is y=mx+b where y is MAP in inhg, and M = mass in lbm/event. Y is slope (taken from tune before aux was turned on) B = zero offset
83.35 = M* 30626 +2
M = 0.002656.
6500rpm = 3250 events per minute (events are intake strokes basically) = 8.6328lb/min per cylinder * 4 (number of cylinders) = 34.5 lb min. @100 degrees F. Multiplied by the same density factor below of 60 vs 100 degrees is 37.1 lb/min. I believe that is a little high as the exhaust backpressure at that boost will start to bring that number down.
Just to check my work, I used the same numbers but current- 29.017 times 0.865 (13% STFT removal) = 25.15 (this assumes 100 degree F temp). Multiplied by (0.0763/0.0709) (density at 60 vs 100 degrees F) = 27.06lb/min. The actual value calc’ed by the ECU was 27.15lb/min. You can see its pretty close using the same calculations.
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