Is it better to run brake ducting to a hole cut in the brake dust shields (say a 3" hole), or remove the brake dust shields altogether and run brake ducting to them without it?

 

For what racing?

 

weekend warrior...autox and the typical 20 min road track session

 

http://www.honda-tech.com/zerothread?id=60722

 

the first method is probably best. the aftermarket solutions all seem to have a "shield" around the hose. I would imagine it probably shields the air flow coming out of the hose so it's directed towards the center of the rotor.

but i've seen home made kits just like you described and directed at the rotor surface to be nearly as effective.

friend of mine with a S54 M Coupe ran that set up at thunderhill and laguna seca and experienced no loss of brake power. At thunderhill, he ran 30min sessions.

 

I ran at VIR doing HPDEs and never ran into fade problems with Hawk HP+ pads, Brembo rotors, and Valvoline Synpower brake fluid. And we did 3 20 minute sessions each day.

You can even go up to Motul MB600 fluid for even higher temperature saturation.

 

The reason for that is because vented rotors use the fins sort of like a centrifugal fan, so the more fresh air you can put there, the more it will spin through.

BUT, if you're trying to reduce fade, the caliper is of more importance to cool than the rotor, assuming you have good pads.

 

No its not. The caliper is not a heat sink, the rotor is. If you lower the temp of the heat sink, you'll lower the temp of the whole system.

However any air you can get in there is better than no air.

 

i've been reading up that this all depends on the brake system...it is easier to focus more air through a system that creates a vacuum (reading up on f1 brakes the rotors are designed to create a vacuum like a compressor wheel on a turbo charger...by creating a vacuum its ducting runs through a system designed to pull air through decreasing braking temps)...basically a ram air effect with a compressor forcing even more air through it

on a normal economy car with stock brakes the dust shield impedes air flow (and heats up retaining heat in the system) even with ducting b/c you are trying to force air into a system that does not dispell it easily (no vacuum)...removing the shield and running a duct to the rotor seems to be the best method

 

my stock rotors are like that. basically it's directional and when installed correctly it looks wrong but it's right. with vanes should curve towards the back of the car not front of the car.

maybe you can also try cutting the leading edge of the dust shield and make a funnel like shape. I think the NSX has a similar deal stock and Dali Racing makes a mega phone sized one.

Found the pic: