san~man said:
You have evidence to back up that claim?
Many, if not all of the supercars manufacturers have drilled, slotted, or both types of rotors on their cars. That includes Porsche, Lambo, Ferrari, etc etc.
Ever see a $3000.00 Brembo Grand Prix rotor system upgrade use regular rotors? I haven't. How about a ceramic Porsche GT brake system? Slotted and drilled there too. Murcielago? Drilled ceramic brakes. I'm sure they all don't do it for the "bling."
You get the picture....I'm just asking for proof of your claim.
Drilled rotors grew from the use of racing-type pads which expel gases when heated. That's it. Another reason is weight reduction.
Drilled rotors offer no cooling advantage at all. They are drilled perpendicular to the airflow stream so there is no flow at all through them. WHen the racing pads expel their gases, they escape through these holes. Most modern street cars however do not expel gases. Some of these exotic sports cars DO use the special type of pad which requires the holes.
Also, these exotic cars have 13 and 14" brakes. That's a lot of mass. Mass and surface ares is what cools the rotor. The bigger the rotor, the more heat it can aborb. Also, the plain faced rotors have a bigger surface area also helping with cooling. When you have a rotor so big, you have excess cooling so drilling the holes will not affect it much and it reduces some weight. Anyone who's done the 13" upgrade knows these rotors are heavy! These little rotors on imports are maybe 9-10" big so they don't have a lot of mass to begin with. Crossdrilling rotors reduces their mass even further hurting their braking a tad.
GM brake engineers have done some testing on the C6 vette and have discovered that the crossdrilled rotors they offer on the vette do help in top end deceleration. They speculate that at high speed braking, the speed of the rotor passing the holes scrapes off a thin later of glazing at each pass allowing more fresh pad to bite. This was only at high speed though, like 140-180MPH and the difference was minimal. At lower double-digit speeds they didn't notice a difference.
However, the rotors on these cars are better constructed than some of the ebay cheapo rotors. Even price Brembo or Baer crossdrilled rotors? Almost $300/pair.
Just some of the stuff i've learned through reading the "crossdrilled vs plain" rotor threads that always pop up.
Personally, on a street car, you won't notice a difference, but be aware that cheapo crossdrilleds can crack on you.