metalshark -
(I'll give it a try, but others can describe it better than me)
The idea is the opposite of the Cold Air Intake (CAI). The idea with CAI, as I understand it, is that the colder air is supposed to be more dense ("heavier"?!?!?), so it has more oxygen by volume. The car's ECU/PCM sees more oxygen in the exhaust (02 sensor) and therefore adds more fuel to maintain the 14.7 stoichiometric Air/Fuel Ratio (AFR). The added fuel is a "richer" mixture that increases HP.
The idea with the Warm Air Intake is just the opposite. The hotter drier air has less oxygen in it. Based on the above rule, the AFR is leaned out. It's like driving on a hot dry day in the desert (without the overheating part,
). It's a way to trick the ECU/PCM into leaning out the air/fuel mixture.
This concept has been used by Honda Insight owners in the winter months to maintain good MPG.
Distinction: In high performance applications, the way the engine is being used is different than eco-hypermiling applications. In high performance, then engine needs cooling because it is being used to it's limit. In eco-hypermiling, the engine is most often *not* being pushed to the limit. It is safe to "keep the heat in" because the engine isn't being driven to the limits of it's performance envelope.
Does that make sense?
CarloSW2