nice brake upgrade

[NoHachi]

Ah, true, discs do get really hot (and they need to, as most race pads need a minimum temp to get decent friction coefficients). What I've seen is that you can go far over 650 degrees disc temperature with small discs..and all sorts of bad things start happening.

Full race pads will usually stand up to the heat but wear at incredible rates (like one set of Carbone Loraine RC8 per track day, bye bye 280E).

Biggest problem is that the fluid (assuming that DOT4 racefluid of DOT5.1 high-temp is in the system) inside the callipers will start boiling due to heat transfer from the discs, through the pistons.
The best extreme use brake fluids (like castrol SRF) have a dry boiling point of 310-320 degrees Celsius at best. Put that fluid into a small space with a heat emitter at 650+ degrees and you have a recipe for trouble.. To get an idea of your brake temps, but don't have any tools try and use this simple reference:

degC color
400 Red heat, visible in the dark
474 Red heat, visible in the twilight
525 Red heat, visible in the daylight
581 Red heat, visible in the sunlight
700 Dark red
800 Dull cherry-red
900 Cherry-red
1000 Bright cherry-red
1100 Orange-red “{*}

(stolen from: http://hearth.com/econtent/index.php/wik...ess_Steel)

On a stock AE86 with the OEM 90 RWHP or so you will be fine with the stock system. If you are planning to upgrade, then its easy to calculate the extra load on the brakes through increased speed potential. If you are planning a N2 racing monster replica on 13inch wheels, better use the biggest and fattest discs that you can stuff under there. Even then I think a decent driver with 240hp at his disposal will boil them pretty quick. Start looking at brake duct fans and brake fluid recirculators.