Given stable AFR, and steady open throttle, and assuming negative misfire, can crank horsepower be caculated to a fair degreee of accuracy from accurate MAF output ?
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Would AFR 12.4 be expected to make around 6 or 7% more torque than Stoich ?

 

Yes and yes.

 

12.4 afr NA or boosted?

 

It can tell you airflow very accurately. To turn that into a power number, you would need to calibrate it on a dyno.

 

Most engines are tuned anywhere from 11.5 to 12.5 at WOT. Do not run 14.7 at anything other than cruising speed or idle.

MAF's can tell you how much air the motor is sucking in. It is a very good baseline indicator to see if a new mod or tune made a change for the better. I get a kick out of the guys that talk about boost pressures as the reference of 'power'.

 

Ignoring transients, and assuming steady-state stable AFR in the 'Best Power' range around 12 to 12.5 AFR, would either of these formulae reasonably approximate gross crankshaft HP ?

MAF #/minute x 10 = HP
.or
MAF g/second x 1.1 = HP
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. Again, speaking in terms of rough estimation...

 

The Lb/min x10 = hp is a rough guestimate. A better way is to look at fuel consumption (injector pulse width) with a known injector size and AFR. Again, any of these need to be calibrated on a dyno. I did that many years ago using dynamic cylinder air and it actually tracked very well for my setup. I made a thread about it if you want to search.

 

Any further refinement on the Airflow vs Horsepower math ?
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Would like to make PID, and have a HPtuner column : "Horsepower"