RAudi Driver

I'm bringing back subject that's been beat to death but I still don't have an answer. Powerhound's diffuser thread has me inquiring. Looks like it's going to be a very nice piece of aero.

So the question is, Does the deck lid fan pull out air out of the engine bay or does it suck in the outside air and push it through the engine bay and out through the bottom? Schools of thought on each make sense where hot air rises so shooting it out the deckled sounds like the quickest and most efficient way to cool it down. However, others have stated that it actually sucks in cool outside air and pushes it out the bottom, thereby preventing all that hot exhaust air from prematurely aging the hoses and plastics in the car. Also if the fan sometime operates while the car is in motion or at a stop light, it gets aided by a wee bit of forced intake.

I honestly have no idea which way the wind blows, but was always under the assumption that the fan pulled air into the engine bay.

Up for discussion.

8Lug

The fan blows air downward. It sucks the air from outside in the same direction as the air is forced In through the scoops on the engine cover when the car is moving. If it blew air out, it would be fighting the ram effect of the scoops once car is moving. 100% verified.

Belinko

yup, fan pulls the air in. typically only comes on when parked or at a stop light or in traffic, otherwise it ain't doing much.

That's why opening the rear hatch after beating on the car makes the most sense, instead of relying on a tiny fan too cool down the beast.

One time I was headed to the track. I got stuck in some bad LA traffic, temp reading on the cluster was 110F, surface temp on the freeway would've been 130+F. I did have the AC on, I ended up getting a coolant warning (overheat) on the cluster, while creeping along, no air flow across the radiators +AC. I pulled off the freeway, opened the decklid and turned off the car for several minutes. I found a shaded area and drove the car in to the shade and waited for about 30min to allow the car to cool down. I got back on the road, I stayed on the street as opposed the freeway and had the AC off. As long as the car was moving coolant temps stayed reasonable and once I got through the traffic, no problems. It was a little scary for moment seeing a coolant/overheat warning. I guess that's how people would kill air cooled cars in LA.

RAudi Driver

Good to know. When I pull back into my garage after a spirited driving day, I position two box fans at the rear of the car. With the read lid open, one fan is blowing air down on to the engine which the other is on the ground pulling air from underneath the car. I started this when I thought my fan was not working. It works and now I only do the fan thingy in the hottest of summer days.