Intake Air Temp (IAT)¶
The temperature of the air entering the engine. Hot air is thinner, so it carries less mass — and it changes the knock picture.
What it is¶
The IAT sensor measures the temperature of the air entering the engine. Where coolant temperature describes the engine's metal, IAT describes the charge — and air temperature directly sets air density.
Why it matters¶
- Charge density — in the speed-density equation, air mass scales inversely with IAT. Hot air carries less mass, so it needs less fuel. A heat-soaked engine (high IAT) that ignores this will run rich.
- Knock — hotter intake air raises combustion temperature and lowers the knock limit (by about 0.08° per °C above 30 °C), so it also nudges timing.
How to tune it¶
IAT is an input the speed-density math already accounts for. What you manage is heat: when the engine heat-soaks and IAT climbs, the charge thins and the knock limit drops, so pull a little timing or richen the mixture in knock-limited cells.
Rule of thumb
If fuelling and knock both drift the same way as the engine bay heat-soaks, suspect IAT — it affects density and the knock limit together.
In the game¶
The IAT bar in the footer TEMP box shows the reading, which feeds the air-mass calculation and
the knock model continuously.