If anyone's interested, here are some temperature measurements I made of the temperature difference between the free airstream in front of the car (1985 XR4Ti) and the air filter box. I used 2 type-T thermocouples (24awg). I placed one junction at the grill in the bottom of the air filter box. The other junction was taped into position sticking up from the front of the hood about 6" into the outside air stream flowing over the car. I then drove the car on the freeway, and in stop/go traffic. For some trialsI removed the filter box top, so that the intake was drawing air from inside the engine compartment. For other trials I kept the top of the filter box in place so air was drawn from the scoop extending into the RF fender area.
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Freeway (70 mph) Stop/Go city traffic
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Intake from fender 2.8-5.1 C 8-12 C
Intake from engine 4.7 C 15-35 C
compartment
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The body of the table is the temperature __difference__ calculated
as filter box temp minus outside free air temperature. Units are
degrees C. So, from these data it looks like the incoming air
charge is generally cooler when taken from the fender area, especially
when driving around town, but at freeway speeds there doesn't
seem to be much difference.
