To further show that VE is not 80% at cruising, I used data from my car that I datalogged this morning. Here goes:
Columns b, c, and d show three random points.
You can see my HP calculation is based on BSFC/Fuel Flow (as per
ATI Procharger). BSFC is a rough estimate, but you can see that at the speeds listed, those HP numbers should be ballpark. The drive was with headlights on and no heater running. My theoretical VE is not based on A/F ratio's.
Again, your A/F ratio math is based on a wide open throttle VE of 80%. When cruising, your VE is not 80%. Your A/F ratio is therefore incorrect since it is based off of your VE being way too high.
I used formulas from here:
Volumetric Efficiency (and the REAL factor: MASS AIRFLOW), by EPI Inc..