For the most part, stock MINI brakes and even the beefier JCW calipers do a decent job of dissipating heat at the track. I generally advise students to run a higher temperature brake fluid and to get some better brake pads like Hawk HP Plus and they should be good for most 20-25 minute HPDE sessions. But for those days when you want to run longer or the ambient temperature is already approaching 100 degrees, you may need some additional cooling. That’s when this DIY will pay off.
The basic idea is pretty simple: The air in front of the bumper is a high pressure area. The area behind the wheel in the wheel well is a low pressure area. Create a path between the two and air will flow through and aid cooling. It won’t be as dramatic as dedicated ducting pointed directly at the hub, but it also isn’t as troublesome for the 99 percent of the time that your aren’t at the track. Expect to spend $10 to $75 and a couple of hours of your time. You’ll need a three inch hole saw, some zip-ties, and some tubing. You’ll loose the use of your foglights (if you have them) but you can put them back in the winter.
You might have luck just holding the tubing behind the bumper cover with compression, but I ended up fashioning a make-shift duct out of an old set of fog light covers (MINI part numbers 51711481435 and 51711481436) which are about $19 each. Just cut the center out and add a screen to keep out debris. Attach about a foot of tubing to the other end and pick where you want to cut the wheel liner.
If you’re trying to stay really low tech, use dryer vent tubing and gutter guard, otherwise invest in a three foot section of silicon brake duct tubing and some wire mesh (I’ve tried both, silicon tubing is easier to work with.)
Attach the tubing to the wheel liner with zip ties. Wire mesh comes in handy here too. when you’re all finished, you can hardly tell anything has changed. Good for a 50 degree drop in caliper temps at Summit Point in August.