TRIFECTA: ECM Calculated Horsepower and Torque

The interesting reality is these numbers are only predictions - there is no specific hardware in the powertrain that can measure ACTUAL delivered engine torque. However, the predictions are extremely accurate so long as the mathematical model behind them is correct. Initially implemented as a series of 78 three dimensional "coefficient" tables located in the ECM, they have grown to become the cornerstone of everything from idle control, to boost control, and things like the way the accelerator pedal feels in the vehicle. The end result is commanded timing, throttle blade position, and a host of other things are directly affected by how much power the engine is predicted to be making. The so-called ECM power-reported numbers are the end result of these calculations.

These tables describe how manifold pressure, measured airflow, timing advance, and even the commanded fuel ratio affect the engine torque output under all operating conditions. As vehicles are modified away from the factory configuration, it is important to keep this model accurate by adjusting the coefficient tables.