If you've ever lapped a roadcourse with the puny LT1 single piston front brakes, you know they become "less than adequate" quite quickly after repeated use at high speed. The single most cost-effective way to make the brakes last longer before fading and to increase pad and rotor life is ducting air to the rotors to try and keep them cool. That's why nearly everybody I know that regularly takes their car to roadcourses has some sort of brake ducting.

I was originally planning to install simple "bumper ducts" in the airdam as many others have done. Then one day it struck me--with all the really steep driveways where I live (including the one to my apartment complex), I scrape my airdam on the ground on a daily basis.

I figured if ducts were mounted to the airdam, they wouldn't be long for this world. Even if I didn't beat the hell out of them to the point of damage on a daily basis, every time I pulled up a steep driveway I would be worried about them. That wasn't something I wanted to live with in my daily driver--I didn't want to worry about the things every day. I wanted to place them up in the air and out of the way. Some sort of "permanent" solution that I could simply forget about after installation.

Then one day, when walking by a '98 Camaro, I noticed how its foglight location would be an absolutely perfect place to take in air for the brakes. I started thinking about how I could do something similar on my car...and this is what I came up with.

Here's How We Did It:

I bought the NACA Ducts and Stainless Wire Mesh from BSR.
The ducts are the 2 1/2" clear ones (Part # BSR.001.WCS) and were about $20 each. I decided to go with the 2 1/2" ducts instead of the 3" ducts for a couple reasons. First, the 3" ducts are huge. I wasn't so sure I wanted to cut holes quite that big in the front of the car (although there is plenty of room). Second, I wasn't sure I'd have enough room to run 3" tubing the way I wanted--all the way to the rotor--without it rubbing on everything. Now that I've done it, I'd say it might be possible with 3" tubing but I wouldn't guarantee it. My 2 1/2" tubing comes very close to rubbing the tires at full steering lock.

That was another requirement for me--the car is a daily driver and must be able to maneuver in and out of tight parking spaces. I really didn't want to have to worry about rubbing the ducting off every time I parked the car. Anyway, I figured the difference in airflow would be more than made up for if it allowed me to get that air into the center of the rotor.

The stainless wire mesh is the eight squares per inch (Part # AGS.1.8X36) and was $10 for three square feet (way more than I needed). It's high quality stuff--very strong and stiff (it will hold a shape). Although it probably impedes airflow slightly, I did not like the idea of directing large rocks traveling 100 MPH into the centers of my rotors.

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The first thing to do was paint the ducts. Since I have absolutely no paint/bodywork experience, I doubted I'd be able to put a nice, smooth, durable finish on the ducts without spending way more time and effort than I wanted to. So, I took the easy way out--since the ducts were clear, I painted the back sides with a can of spray paint from Pep Boys. It actually turned out pretty well. After about 3 coats, the front sides of the ducts had a nice, smooth, shiny finish with a very durable "plastic clear coat." The main problem with this is after you touch up the edges of the ducts on the car you can see the touch up paint and the duct paint are on slightly different levels. It's only noticeable if you look really closely though.

If you have paint/body experience (or a lot of patience) you should have no trouble making them look better than mine by "doing it the right way"--installing the ducts onto the car, getting everything filled and sanded smooth and spraying them from the outside the same way you would if you were painting the fender. One of these days when I have the time and patience I'll "do it right."

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Then I installed the screen to the ducts. I formed the screen on the end of a piece of 2 1/2" exhaust pipe, cutting little triangles so the edge didn't try to fold. I used a large tin snips to cut the screen. I put down a layer of electrical tape on the ducts to keep the screen from scratching the ducts, put on the screens and then put on another layer to temporarily hold the screens in place.

These are the panels I'm talking about, with the holes for the tubing cut into them (ignore the reflections, it was raining):

If I had to do it over again, I'd probably mount the ducts a little farther forward so the tubing didn't have to make such a sharp bend to avoid the inner fender. If you go too far forward, the bumper cover becomes "less flat" and that will make it difficult to mount the duct. Also, be sure to try and make the ducts level with the ground or they'll look funny and won't flow well.

I cut the bumper cover with a Dremel tool. I cut most of the area out (staying well inside the lines) with a high speed cutting bit (steel, thin, kind of looks like a drill bit). After that I used a sanding bit to shape the hole toward the lines, staying a little more than 1/8" inside the lines all the way around. Once you get that close you'll need to place the duct behind the hole and gradually take the hole up to size to match the duct (so that the edges of the hole are even with the side walls of the duct).

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For the NACA duct to flow efficiently, you need to shape the cut in the bumper cover in a specific manor.

You'll see that the plastic from which the cover is made is rather thick. The biggest problem this causes is a large "step" at the leading edge of the duct from the outside of the cover to the floor of the duct. That step will keep a lot of air from entering the duct. You need to sand this step down, basically making the front cut in the bumper at an angle that closely matches the angle of the duct floor. Due to the extreme angle and the thickness of the plastic, the leading edge of your cut should be more than 1/2" wide, like shown below:

The sides (or top and bottom when installed on the car) need to be as sharp as possible. This will cause vortices in the airflow around the edges that will "suck in" the thin boundary layer of air that would otherwise pass by the duct. You'll probably want to round them off a little so that the paint doesn't chip easily, but keep them fairly sharp.

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Then, simply glue the ducts into place. I used a two-part "5 minute" glue sold at Pep Boys (the 60 second stuff sets up much to quickly). It was 2500 psi tensile strength and said it stuck well to plastic (they have lots of different types from which to choose). Be sure and clean the inside of your fender pretty well so the glue will stick.
You will then notice a gap between the duct and the bumper cover as shown below. There will also be some glue squeeze out to varying degrees in this gap. That's what Bondo is for!

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Now, for the important part. You can take air in any way you like but if you don't get it into the rotor it won't do you much good.

After hearing of a number of people that had their "Home Depot Plastic Pipe" systems melt, I wanted to use better materials--like I said, I wanted to build them and forget about them.

To end the ducting at the rotor, I used 2 1/2" 304 Stainless Steel exhaust pipe. You can get a three foot chunk from JC Whitney for about $30. It won't rust, it won't melt and it won't break.

You can see the basic shape of the end pipes in the pic below:

Then, test fit them onto the spindle. You'll see they kind of naturally want to sit at an angle. This puts them at an angle with the rotor--mark the angle and cut off the oval end at that angle. Then cut the excess length from the round end so that it will clear the swaybar endlink at full steering lock.

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I attached the ends to the spindles with 2" U-Bolts from Home Depot (2" instead of 2 1/2" because the end is ovalled). I bought four so I could double up the bottom part for an added margin of safety as it will bend around the spindle when you tighten it down.

Here are some pics:

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Here is the end result: