road racing: how much rotor for 2000lb car; i.e. 10.5"?

im trying to locate some generic advise for how much rotor a vehicle described in the title may need to do its job effectively. i stumbled across a post on a miata forum where a member mentions, "We looked at the temps generated with different size setups. We could not find a reason to go bigger than 11 inches front." http://forum.miata.net/vb/showpost.php?p=292643&postcount=11

another piece of information that should be useful is knowing the car in question has about 300whp and weight with driver is below 2200lbs more likely 2100lbs.

if im missing details that will help formulate an answer just ask.

Contact Todd Cook at TCE Engineering. He's a brake specialist and a racer so he may be able to help you.

480-967-7901

David

It also will depend on if you are planning on using stock calipers or upgraded ones, and what pads will be used. If you're going for a 4 piston caliper and race pads, you may want to get bigger rotors. If you're going with stock calipers and race pads the car will still brake and cool pretty well, but fade after 15-20mins of hard driving. You can also buy drilled/slotted rotors to cool them down, as well as install dryer hosing for cooling ducts.

Another factor is tires, if your tires have good grip, you won't need to use as much brake to get slowed down.

Good Luck, sounds like a cool car. Steven

+1 for ducting...it really helps a lot. Instead of dryer hose, I preferred to use SCAT or CAT tubing which can be obtained through aircraft supply houses (www.aircraftspruce.com). It wont crimp up like the aluminized dryer stuff.

i just had a lengthy conversation with mr. cook at tce engineering and have more things to consider. he spent his time unstintingly with me and i would recommend if he makes a kits for your application that you consider it.

the ducting to the rotors will be addressed and will likely fabricate a custom shield to direct as much air into the vanes as possible. ordered from aircraftspruce before; great resource to diy person.

as of now it seems like the largest factory to help when considering limitations of a braking system is the weight of the rotor for storing the heat generated from braking. accepting this, im now trying make a brake system that can possible adapt between drag racing(.35" solid/drilled/scalloped) rotors and some vented .810" in same diameter for road racing(maybe slotted, but thats it).

thank you thus far for the feedback.

kinetic energy = 1/2 * vehicle mass * speed^squared

what's the top speed of the car?

AngryCorvair wrote: kinetic energy = 1/2 * vehicle mass * speed^squared what's the top speed of the car?

what type of top speeds do stock c6 z06 and stock 997 911's typically see at tracks? do you mind using this for your data point?

i don't mind using it. it just might be wrong, that's all.

any information shared at this point will be a great help, even if its some anecdotal experience.

My E Prod 2nd Gen RX7 uses the stock calipers and rotors with Hawke Blue front/Black rear with absolutely no problems. The fronts are ducted and the car is slightly north of 2500# with driver. I'm running SCCA Nationals and use the brakes really hard. My tires are 9.5x23x15 Hoosier slicks. I have never had any brake issues with this set-up. The rotors are roughly 10" diameter.

OK for my ITA civic: I get to about 120 then brake for a ~60-70 mile an hour turn, then go from 100mph to a 40mph turn once a lap, fairly hard braking. This is with stock calipers, stock rotors, Hawk HT10's and no cooling ducts, car weights 2250lbs with me in it. I run 205/50/14 Hoosier R6s or Hankook C51's. I have a little bit a fade after 15 laps or so. As long as I make sure to pop out of the draft down the straight, the brakes get cooled down enough to avoid the fade.

Your car will rarely get above 140 no matter what track you're on. If you get some ducting I really think you'll be fine with stock rotors, calipers and race pads.

Steven

Don49 wrote: .

thank you for sharing. what kind of power is this car putting down?

Smack35 wrote: .

thank you and i will ask the same question; what kind of power is this car putting down?

Approximately 200 rwhp, top speed around 135+.

probably 115-120hp. It might get up to 115-120mph. Once I get a tuned HonData ECU the horsepower will be 125+ with top speed of 125+ as well, but I don't expect the braking to change.

Steven

^ and ^^ both of you, thanks.