Reply to "ZF oil cooler"

Expanding on my friend Chris's comment, the problem with using the screened area in the rear for oil cooling (or for an AC condenser as well) is, at low speeds (below 100 mph or so), tuft studies show there is a big swirl of air from over the roof and out the rear 'window' opening behind the car, that actually pushes against the rear bumper. So at low speeds the AC condenser or oil cooler fan should be set to suck air in, not blow it out from inside the rear trunk against positive pressure.

But at higher speeds yet (above 100 mph), the same swirl moves back away from the rear of the car; now there's a partial vacuum of variable size behind the bumper. Trying to suck air in when there's little available has been implicated in blowing AC lines. At those higher speeds where the engine is also highly loaded in 5th gear, you need oil cooler air flow to be from the inside to the outside. DC motors reverse easily but not fan blade orientation on the fan shaft.

Bottom line: unless you ALWAYS drive slow, or always drive fast, that's not a good place for either an AC condenser or an oil cooler. And note that without the trunk tub in place to help direct airflow thru the rear screen, air flows both stock & modified are all messed up both at low speed and at high speeds. Its not as convenient but oil coolers should be mounted in front, and AC condensers work better up there, too. Good luck.