Dave E

I have big reds and AP race rotors with holes in them, I don't know if they are drilled or cast, but they work pretty well. I have the OG kit with the backing plate modified with aluminum to increase the diameter to fit the inside of the rotor, and use 3" Aeroduct hose. Castrol SRF only, Pagid Orange currently, but they have to be properly bedded before each track day and they squeal on the street. I think if enough air is forced through the rotor, the holes will have a net outflow of air to aid cooling, although I question whether 3" hose is enough and I'm working on adapting the backing plate and scoops in front to accept 4 or 5" hose instead, and get some airflow onto the braking surfaces as well. So far this setup works with a 3000lb car and 225 r compound tires, but if I push it further with more grip I don't think it will keep up.

mochman

the holes and slots are to let the gasses escape from braking not cooling

IPSC

mochman is right when a brake pad is applied to the rotor there is an outgassing. The holes and (IMHO the better of the two) slotting gives this gas some place to escape. Holes came first then slotting. The arguments against each are that holes crack and slots wear the hell out of your pads. I have yet to try either for myself. I will try slotting a set of rotors as an experiment though when I get some time.

IPSC

Jon Moeller

mochman and IPSC,
you both need to do some research. Aside from the initial bedding period, modern pads do not produce any gases. Concern over outgasing went the way of the carburetor.

-Jon

Dave E

this is my second set of race rotors with holes and I haven't seen any cracking at all, maybe a different composition in the iron they use?

thesmokingman

From my Subaru experience, Gary Sheehan's WRX in the USTCC runs electric motors in their brake ducting for some good cooling. They run without the motors during rain days, however.

If you feel frisky, you can inject/mist water into the rotor for really decent cooling too. This is a pretty old trick iirc and works by using energy asorbed by the water as its vaporized when it hits it boiling point or something like that.

Also, FIA WRC cars have been using water-cooled brakes for years, on tarmac stages only though. Heck I know where one can even source an AP 6 pot kit complete with radiators for pretty large coin however.

Crazy Eddie

I really feel the most important factor in keeping your brakes cool is using the
correct pad. I have the S4 brakes on my ts and I melted my rotors when the had only 15K miles on them .... Once I switched to Porsche green pads I never had a problem. Well except now the dust will eat the **** out of your wheels
But what the f#$% do I know :-)

thesmokingman

Pads, lines, and fluid do nothing to "cool" brakes. They only raise the point of fade. Beyound that, stuff starts to literally burn up, hence the need to physically cool the brakes.

Dave E

In response to Danno's comment on corrugated hose, Aeroduct brand is lined on the inside (like some other hose) but made in a way to minimize turbulence inside more than any hose I have seen, lined or not. I first saw it in a kit for BMW's but it is used widely in aircraft ventilation systems

DrRon

Dave E

Are you running Pagid Orange on the street? We use them - strictly on track, and they take about 1.5 laps to heat up properly (that's when they start squealing).

Other than that - ATE Superblue, drilled rotors, lots of ducting, but still fade after about 5 laps. We lose about 35 meters in braking for a particular turn on the 993 RSR's whose brakes keep working ok..