mswitz88

I have only found a couple posts about rear brake ducts and it seems the only option people have tried is pulling air from beneath the car.
Example: https://www.s2ki.com/s2000/topic/949...brake-ducting/

I am interested in different options like the potential for using NACA ducts on the exterior of the car. Being a nerdy engineer by day, I want to come up with a more viable solution since I don't feel like pulling air from below the car is the best option both from a packaging perspective as well as an aero/performance perspective. My '03 Berlina is going to be seeing more track time in the future and I don't have any concerns about being able to revert back to "stock". I just don't want the car to look super RICED out if I hack up the bodywork attempting to drop ducts in. If I can come up with a clean way to install the ducts then I'm game for some surgery.

Potential locations I'm looking at would be:
1. The lower fender/side-skirt area behind the doors. Pros: good aero zone (typically medium air pressure to pull from) Cons: Fitment, frame behind it?, possible not big enough to fit a duct.

2. Rear bumper behind wheel well. Pros: easier fitment, plenty of space. Cons: (I'm assuming) poor aero placement. Typically the air is turbulent after the wheel wells so I would be concerned about effectiveness.

3. Above the fenders. Pros: Decent aero spot. I haven't pulled a fender liner to see what's behind it but I'd guess it's accessible. Lots of supercars use ducts here for rear engine cooling and intakes. Not sure how the aero is when the body work is not pre-designed from the factory to guide air to this area. Also wonder how soft-top affects airflow in this region. Cons: hose routing may be difficult from top down, Ugly spot on car to hack up, higher potential for water to funnel down into it.


4. Front? I saw someone post a ducting pic with the front bumper off an AP2 that looked like they had 4 ducts. I'm not sure if the other two were for rear brakes or not. I can't imagine how they could have routed the hoses back to the rear if that was the case but maybe someone has more insight.


5. Under the car. Pros: probably easier install, more discrete, no body cutting. Cons: questionable aero/performance, potential for it dragging, finding good location.

I have access to a CFD program from my work computer but don't have the free time to model the car to test some of my aerodynamic theories out. If someone has a decent CAD model of the car, I could take a stab at running it through CFD.

Any input would be greatly appreciated! If anyone else has successfully attempted rear ducts and has pics, that would be awesome!

slowd16

actually just came across this one yesterday and looked intereting: http://www.motoiq.com/MagazineArticl...rst-Races.aspx

mswitz88

That is a more likable design in my book for underneath the car. At least it looks protected by the frame but I'm not a fan of the hose hanging down that far. Feel like they could have gotten that up and out of the way more. I still wonder how well it performs under the car when there isn't as much airflow to it. Wonder if they did any semi-scientific testing for brake temps with and without...

devildust

Maybe re-read the thread you posted, there is scientific data to back it up. See post #27 from the thread you have a link to in thread 1.

"It works!

I ran an event on the 9th at Sears Point and taped over 1 duct leaving the other one open. I don't have dust shields in the back so I simply routed the hose along the lower control arm and pointed it toward the back of the rotor. Pics coming when I get the car jacked up.

Temps taken with a infrared pyrometer in pits after cool down lap:
- right side rotor temps : 193F
- right side caliper temps: 350F
- left side rotor temps : 187F
- left side caliper temps: 257F

Guess which side was taped over. "

My car is pretty low and I do not have issues with this set up, I myself have never done testing on it but Im sure there is more air flowing through there with this set up.

mswitz88

I saw the numbers in that post but I'm not convinced about the setup and here's why: When I IR'd my rotors/calipers after sessions at Watkins Glen, I noticed variations in temperature from side to side that were as big or bigger than the 93deg change he saw without any difference in right-to-left setup. My rear rotor temps fluctuated between 680-800F depending on the run and calipers fluctuated similarly but I can't recall the temps off hand (lower than the rotors). To add to that, 6 degrees difference in rotor temps is hardly a significant change That, combined with the perceived ground clearance issue, is why I am investigating alternative options.

Apex1.0

My c6 corvette came with factory rear brake ducts. The opening was under the car, in front of the rear wheel well.

Fwtw, I think that will be the most practical location.

devildust

If you are seeing that great a variance I would look into your caliper/pistons, one side might need a rebuild, they may not be moving freely. Just a thought, I know my one side was sticking and killing pads more.

Croc

IMO nothing is wrong with the "usual" under body placement.
it's effective enough...

mswitz88

I was wondering about this as well, actually, and planned to dig into it further when I get to the point of doing the ducts.

mswitz88

I like your placement of those ducts. They seem to be tucked up in better than the other ones that appear to hang down beyond the bottom of the car.

I am still on the fence. I need to get some time to look over my options. I just moved houses so things have been a little too crazy for me to have time to play around with the car. Thanks for the replies everyone.