Alpha-N
Introduction
Alpha-N is a tuning solution utilizing the TPS (throttle position sensor) and engine rotation speed to estimate engine load. This is not a good tuning solution for street vehicles, or turbocharged vehicles for any purpose.
Limitations
Alpha-N is a very limited method of tuning. Utilizing an intake metering device will provide more reliable, and often higher engine output. When configuring Alpha-N, engine load is estimated based on throttle position and engine speed (RPM). As an example of how the ECU will read this, 4,000 RPM with 75% throttle will always be handled as 250 kg/hr regardless of actual intake flow rate (which could be drastically different). This means you will often have less than ideal fueling and ignition timing.
When to use
Alpha-N is really only recommended for track or show vehicles.
For track vehicles, it's recommended to be tuned to each track you visit. Since most track vehicles spend much of their time in high-throttle, high-RPM situations, it is possible to provide a more specific engine load estimation.
Since most show vehicles are not driven very much, an Alpha-N tuning solution is often acceptable and can provide a much cleaner engine bay.