fog light delete and ducting

B8 S4
#1

On the driver’s side there’s a secondary heat exchanger in the B8 S4. Air and rain pass through it. There was a small 3" vent behind it in the wheel liner, but on many cars including mine the wheel liner rotted away. I took a pair of shearing scissors and cut away the plastic gridding behind it to make a full size cut out (6" x 6"). With the wheel pointed to the left, it actually does let a lot of fresh air pass over the inside of the rotors.

I don’t really use the fog lights for anything and decided to remove them to let more air flow over the heat exchanger. On the passenger side, there’s a large air gap behind the fog light. I should be able to run an S-shaped tube and cut a small 2.5" hole in the wheel liner to allow additional airflow at speed near the brakes in the wheel well. My 325i had vents like this.

http://i59.tinypic.com/o0qftj.jpg

http://i58.tinypic.com/117fnsl.jpg

#2

great stuff west. the rs4 guys pull that fog light out and get extra flow to the air box. The B6 guys do the same. There is a big flow gain just by removing the fog. Some people dont care about fog lights im one of them. The flow gained by removing them is a great free mod.

#3

Also cut out the passenger grill slats to match the driverside? Even more flow.

#4

It’ll just drag more. The idea with the tube is to create a ram air effect. Honestly if I can’t mock it up cleanly I’ll probably just cover the hole on the passenger side.

#5

Whats behind the block off section on the passenger side. That might make a good spot for an oil cooler rad or some extended cooling rad.

#6

So you are gonna run brake ducts like this

http://www.lapponline.com/images/brake_ducts/evo.jpg

Or just have air pass into the wheel well?

If it’s the latter, I’ve heard the benefits are not great compared to running a tube up to the rotor.

#7

There is some air pump in that section, otherwise its pretty open. I have my Heat exchanger additional coolant res in that spot.

http://oi62.tinypic.com/20qcisl.jpg

#8

I know those tubes have high efficacy but they’re high maintenance. They tear themselves apart at least every year. If they tear on track they can cause a catastrophic failure if they wrap around the wheel/suspension by pulling out the brake line.

#9

I was about to say that the SAI pump is back there. It would have to be relocated, and some kits use that spot as a heat exchanger tank.

The NACA ducts underneath are still the best way I think. I had that fabbed on my S4, and the RS5 came with it stock. Direct airflow to the wheel well area. Sure there’s not mechanical connection between the wheel well to the back of the rotors, but you can have scoops made that bolt into where the dust shield bolts on to.

#10

West, as you may know, there are 2 variations of these tubes. Neoprene and the legit stuff they use on race cars (the orange ones)…which happen to be made of some material that NASA also employs for ducting on their equipment. These tubes are spring steel reinforced and are very durable. FWIW many factory street cars come with them (those track focused ones).

I agree that it is a hazard if routed or secured poorly. But done right, it has no substitute.
It may be worthwhile going the naca duct route a la Psychotik. If you also still run the dust shields behind the rotors, take those off. Your ducting (whatever option you choose) will be much more effective this way. FWIW i do not run dust shields behind my rotors

#11

Just to back up what psyhotic said. That pump is the secondary air injection pump. Its usless 60% of the year as its just for cold starts in very cold conditions. The pump is used to pump in secondary air to help quickly pre heat the pre cats. Its mostly useless espically if your car is a track car.