reater extent than the stock ones - 116, 82 and 105 degree centigrade respectively. Stock rotors’ readings were consistently better at 96, 86 and 92 degree centigrade. The second test was done to test braking while going downhill. The car was sped up to 40 mph and then put in neutral while going downhill. The car’s speed was then maintained with just the brakes without any engine braking. Once the car had stopped, the temperatures were noted again. This test too, was conducted thrice at three different locations. In this test, the temperature changes for the stock setup were 49, 77 and 14 (from 138 to 152) degrees centigrade. The temperature changes for directional rotors were 59, 82 and 24 (from 141 to 165) degrees centigrade.
Are we caught in some made up marketing ploy to sell more expensive rotors? Let’s dig deeper. If we account for the ambient temperature, the actual temperature difference between the two setup only happens to be 2% for the first test and 1% for the second test. However a negatively biased difference does exist for the differential rotors. The next thing to consider was the mass difference between the two rotors. The stock rotors are in fact a pound heavier than the directional ones. Considering the energy to be the same for both rotors, the same energy is being stored in a denser package in directional rotors.
The most critical point however seems to be the temperature itself. The temperature ranges that this test involved (40 – 190 degrees) were not exactly high. On the track, brake rotors get up to temperature ranges 10 times higher. A better test would then have been, to test the two different setups on the track throughout the day. Under that kind of serious performance, the cooling efficiency really comes into play, more than the mass of the brakes. It’s really a give or take between heat absorption (aided by mass) and cooling efficiency (presence of vanes). This was further proven by a test conducted by Science of Speed, where another Honda S2000 did 56 laps with the two different brake setups. With consistent lap times, directional rotors ran 32.4 degree centigrade cooler on average. The temperature ranges involved here were also as much as 500-1000 degrees centigrade. The conclusion then may be, that performance brakes only shine when they are tested hard. And that we should not let confirmation bias cloud our judgement.