Cool air = better than hot air. In fact I'm surprised that after all these years of hotrodding, the standard open element 4 barrel air cleaner sucking in hot under hood air is still the gold standard.
I have wondered about that too.
When a gasoline engine is idling,
Does it use less gallons in an hour
With hot air?
At idle
Intake side pumping losses are high
Because the throttle is nearly closed.
Hot air has less oxygen per cubic foot than cold air,
So the throttle has to open a bit more
And idle vacuum has to drop,
Therefore more atmospheric pressure is available
To push the piston downward on the intake stroke.
This reduces intake pumping loss.
My 1995 Magnum 5.9 V8 seems to have a complicated fender side air inlet system that sucks hot engine compartment air at idle,
but when the truck is moving gets cooler air from a passage in the fender that has its inlet up by the passenger side headlight.
It is so complicated that it has to be designed that way on purpose.
Since they are using the fender sheet metal as an air passage,
Why didn't the designers get the engine air from a vent high up on the passenger side A pillar. This "snorkle" inlet would have other advantages.
