Because I have a MegaSquirt ECU in my car, I was able to simply install a temperature sensor in the intake and log its readings.

On my car, the intake manifold is usually 40°F cooler than the engine coolant during highway driving.
Intake - 95-100°
Coolant - 140°

I've also had this tempsensor in the aiffilter housing before, and there temps would get close to the same as the outside ambient temperatures during highway driving.


But whenever you get into stop&go traffic, intake/air temps will climb quickly to engine/bay temps again.