QUOTE(naro914 @ Feb 8 2012, 07:49 PM)
Actually under the car is negative pressure. That's why, at speed, a car with good aero actually sucks down to the ground.
Under the car is the second best place to dump the air.
I know how well it works from the way I set up the oil cooler on my race car.
SCCA Prod rules are very strict about not cutting holes in the bodywork and underbody so I had to get creative. My cooler air path is in through one fog light opening (cutting a same size hole in the panel behind is allowed) and out through the little holes behind the airdam. The vertical bumper opening has about the highest pressure of any part of the car and behind the air dam has about the lowest. My oil has never run cooler than it does with the current setup.
In cool weather I can cover 1/3 to 1/2 of the inlet and still not overheat.
The only downside is the increase in pressure under the car. At the speeds of FProd it wasn't much of a factor though.