How effective are air ducts that funnel air to the brakes?

I know the Evo VII has it, any others?

 

What air ducts?


I know that Kevin M added air ducts for his Brembos, but for a stock CLS?

 

I know the TL-S/CL-S don't have air ducts and I don't plan on adding any. I'm just wondering how effective they are in general.

 

1. Kevin M said that the Brembos were everything that anyone could expect for street braking with stock pads and NO ducting. However, on the track, he said that the ducting was required. He said that he removed the inner dust shield and he (and or with other help) managed to fashion a duct that pulled air in from the front grill to the dust shield on the inside of the brake disk. (He remarked that just removing the dust shield would probably help the brakes (in our cars) to cool better (he said this to me).

2. F1 cars live and die with ducted brakes. Instead of just using the thermal "bulk" properties of the disks, and wheels to store the heat energy from a stop (my wheels can get hot enough to have steam coming from them), the forced air allows the air to be vented to the inside of the vented disks. The vented disks have a natural tendency to pump air from the inside of the disk to the outside (well, I know that F1 and Brembo brakes have a nice open area that exposes the inner vents at the center of the vented disk). The combination of cold air rushing in, along with the "natural" pumping action of the vented disks allows for "forced air cooling. The outside of the disk presents a flat area, but there is more exposed surface between metal and air on the inside of the vented disks. If you can pump air in through them, you really help the cooling.