Hey gurus,

What is the MAF Hz to lb/min formula? I remember somebody sending me it awhile back but I lost all my tech email from a server crash.

I know I should just be logging lb/min in evoscan but I didn't...

-Bryan

 

I made one a long time ago...I'll see if I can find it. IIRC, it was a polynomial equation. I'm not sure how accurate it would be with aftermarket intakes, etc, but it should get you close enough.

I think EvoScan just uses my estimated equation for load/95 = g/rev, then mutiplies by RPM to get lb/min. Again, not the most accurate.

In the meantime, add mrfred's mass air calc to your ROM. That should be the most accurate and what the ECU is actually using and calculating. It was derived from the OBD-II calcs with help from Acamus.

 

OK, this is what I have in my MAF Scaling spreadsheet from a long, long time ago...the massaircalc is for g/s:

#Forumla to calculate g/s from airflow,baro, and intake temp (for 0<Hz<1600)
airdens=Atmospheric_Pressure /14.6956/.08026/(Intake_Air_Temp +273.15)*28.9
massaircalc=(-1*10^-08*AirFlow^3 + 2*10^-05*AirFlow^2+ 0.1228*AirFlow - 1) *airdens


#Forumla to calculate g/s from airflow, baro, and intake temp (>1600Hz)
airdens=Atmospheric_Pressure /14.6956/.08026/(Intake_Air_Temp +273.15)*28.9
massaircalc=(-1*10^-08*AirFlow^3 + 2*10^-05*AirFlow^2+ 0.1228*AirFlow - 1)*airdens

Obviously, you would also need baro and intake air temp in your logs for these to work.

 

Thanks!