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Alpha-N Strategy

Alpha-N in Capoworks ECU calculates cylinder air mass from RPM, throttle position (TPS), air temperature and a dedicated Alpha-N filling table. It is useful where TPS is a more reliable load indication than MAP, such as some individual-throttle-body or high-overlap-camshaft installations.

How Alpha-N works​

Select Fuel strategy > Alpha-N in Base Engine > Base Engine Settings. Open Fuel > Alpha-N filling to tune the 16x16 TPS/RPM table.

The table value is Alpha-N cylinder filling at the configured reference pressure and selected air temperature. It is not a Speed Density VE percentage and it is not a fuel pulse width. The firmware combines that filling with engine displacement and temperature to calculate cylinder air mass before the normal fuel corrections are applied.

TPS and RPM breakpoints must be finite, non-negative and strictly increasing. The TPS axis must remain within 0 to 100, and the RPM axis must end at or below 18000 RPM. Duplicate adjacent breakpoints are invalid. The supplied table values are initialization data, not a validated calibration.

Air-mass policies​

Use Fuel > Air mass model settings to choose the temperature and pressure behavior:

  • Air temperature source selects Tcharge or IAT.
  • Standalone Alpha-N: multiply MAP makes standalone Alpha-N use effective MAP as the pressure in its cylinder-air-mass calculation instead of the reference pressure. Configure a usable measured MAP source or, when enabled, the MAP estimate policy.
  • Alpha-N barometric compensation corrects the pressure calculation with measured BARO relative to the calibration reference. Its Alpha-N calibration reference pressure must match the pressure used when the filling table was produced.

If the separate idle VE table is enabled, configure Idle VE load source for the idle overlay. The choices are model default, measured MAP, TPS, or effective MAP. For model default, Alpha-N uses TPS.

Combining Alpha-N with Speed Density​

Use Fuel strategy > SD + Alpha-N when both models should contribute. Its authority table mixes their calculated cylinder air masses: 0% uses Speed Density only and 100% uses Alpha-N only. The authority table can be indexed by TPS or by strictly valid measured MAP.

The separate VE blend tables do not select between SD and Alpha-N and do not perform this air-mass blend. See SD + Alpha-N Air Mass Blending for the current menu, policies, fallback behavior, diagnostics and manual tune-transfer requirements.

Firmware and tune compatibility​

Use the matching generated TunerStudio INI for the installed Capoworks firmware. The current air-mass layout uses flash data version 20032; older binary tunes are not migrated automatically. Back up the old tune, transfer values manually with the matching generated INI, and recreate former 4x4 cylinder fuel trims in the appropriate SD or Alpha-N 16x16 model family.