MGL Avionics User Forum

Do you have to have a MAP sensor to set up the HP calculations in the Iefis. Challenger 10.4. I'm trying to figure out how to use the HP and lop rop functions. I have fuel injected io360 engine. Didn't think I needed a MAP sensor so I didn't get the rdac with MAP.

The engine power can be calculated from equation:

HP = RPM * torque * scaling (depends on units)

The torque produced depends on:

• compression ratio (engine specific constant)

• volumetric efficiency (engine specific: depends on RPM)

• Air/Fuel ratio i.e. mixture

• ignition timing

• MAP: i.e. "how much mixture is filled to the cylinder". varies between 30%-100% of maximum full throttle

Assuming that timing, F/A and VE "don't matter too much", leaves the MAP as the dominant parameter which has a huge effect. Therefore no HP measurement without MAP.