Brake fans vs ducts
11-08-2010, 03:46 PM
#1
Safety Car
Thread Starter
Brake fans vs ducts
Anyone tried these? Any difference in cracked rotors? If the rotors are cracking due to differences in cooling rates, would this help? It seems like the outer would cool quicker due to more air flow when the car is parked so fans might help vs the inners use the hub heatsink vs. outers have the wheel as a heat sink.
Thanks.
Thanks.
11-08-2010, 07:42 PM
#2
Former Vendor
Most of what I have seen have fans inline with ducts to cool the rotors when in the pits, following the pace car, etc....maybe other reasons, that is all I can recall right now.
11-09-2010, 02:32 PM
#6
Racer
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I had them on the GTO for a while.
They were too much fuss so I took them off again. I don't know if they were of any benefit over the normal style.
Then again, with two evenings spent driving around, installing and removing ducting and pointing an IR thermometer at rotors, I was never able to demonstrate *any* benefit from "normal style" ducting either. And I had two 3" ducts per side.
They were too much fuss so I took them off again. I don't know if they were of any benefit over the normal style.
Then again, with two evenings spent driving around, installing and removing ducting and pointing an IR thermometer at rotors, I was never able to demonstrate *any* benefit from "normal style" ducting either. And I had two 3" ducts per side.
11-09-2010, 02:43 PM
#7
Safety Car
Thread Starter
I am thinking fans, as in marine fans that put out 135cfm.
Not sure if ducts are doing much for me either. I get 5-6 days out of seasoned rotors.
Not sure if ducts are doing much for me either. I get 5-6 days out of seasoned rotors.
11-09-2010, 04:23 PM
#8
Race Director
135cfm isn't very much.....a 4x4" square will generate nearly 1000cfm at 100mph, a 4" round hose around 700cfm. Fans might be useful if you have no place to put in a duct on the nose, or if you run really slow circuits, but I think most any straightaway with normal ducts will perform just as well overall.
Like a fan/shroud no your radiator, having the fan might actually inhibit flow on the high speed areas.
I think more powerful fans might be worth trying though....maybe a 6psi Vortec for each rotor??
Like a fan/shroud no your radiator, having the fan might actually inhibit flow on the high speed areas.
I think more powerful fans might be worth trying though....maybe a 6psi Vortec for each rotor??
11-09-2010, 04:52 PM
#9
Safety Car
Thread Starter
Thanks David.
What flow do the stock C5 ducts allow?
I'll just keep cracking and replacing. I just need to get better at predicting the cracking so it doesn't happen on my outlap for TT sessions.
What flow do the stock C5 ducts allow?
I'll just keep cracking and replacing. I just need to get better at predicting the cracking so it doesn't happen on my outlap for TT sessions.
11-09-2010, 05:25 PM
#10
Team Owner
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CI 4-5-6-7 Veteran
FWIW, I've run more than a few sessions knowing I probably had a cracked rotor. 1: they get better as they get hot, 2: if you clamp down on the brakes hard enough, you barely feel the vibration. Hard to give up those prime late morning sessions.
11-09-2010, 05:32 PM
#11
Former Vendor
I had to make 4 brake upgrades on one car as I made it faster and faster, I love threshold braking, last second application, deep into the corners, off the brakes and on the gas, great for making hot brakes!
I cracked one rotor all the way to the lug nut hole, I did not go out for the last session that day, to say the least and had to drive 70 miles home on it but made it of course
I then went from Brembo stock STI calipers good quality aftermarket rotors, with cooling ducts, to a Stoptech BBK. This was not your typical Subaru Forester, not much of it was stock. 9.5 wheels, 285 DOT race tires, JDM drivetrain, custom dual adjustable coilovers, big IC and radiator, Recaro seats, harnesses, so I could stay in the seats....might not of had the power on long straights but kicked a lot of **** in the turns, more than you might imagine
Rick
I cracked one rotor all the way to the lug nut hole, I did not go out for the last session that day, to say the least and had to drive 70 miles home on it but made it of course
I then went from Brembo stock STI calipers good quality aftermarket rotors, with cooling ducts, to a Stoptech BBK. This was not your typical Subaru Forester, not much of it was stock. 9.5 wheels, 285 DOT race tires, JDM drivetrain, custom dual adjustable coilovers, big IC and radiator, Recaro seats, harnesses, so I could stay in the seats....might not of had the power on long straights but kicked a lot of **** in the turns, more than you might imagine
Rick
11-09-2010, 06:04 PM
#12
Team Owner
11-09-2010, 06:12 PM
#13
Race Director
The challenger and charger folks have done some testing with the bilge fans with tested positive results.. Lower rotor temps by about 200* IIRC
Do a search over on lxforums.com in e racing section.. It had a nice little write up and testing results
Do a search over on lxforums.com in e racing section.. It had a nice little write up and testing results
11-11-2010, 01:04 AM
#15
Tech Contributor
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You can get 3 inch marine bilge blower fans that will move over 200 cfm. However, the best way to mount them may be to Y them in with the stock duct so they are adding to the air flow instead of blocking it at speed.
Bill
Bill
11-11-2010, 04:25 PM
#16
Former Vendor
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Depends on the use and how the ducts are ran. Most of the Corvettes can lend themselves to being able to draw in enough air as long as it is routed correctly to the wheels like in a brake duct kit.
In some cases it is needed to run a brake duct fan, and there are a number of ones out there you can get. Like on our TransAm cars we needed them for the rear brakes and also the diff cooler as there was just no air flow to that side of the car.
If the air coming in is faster than the fan, then the fan becomes a restriction so you do have to watch that. In very extreme cases they will run water sprayers too, like the Euro Semi truck races.
For most guys doing 20-30 mins sessions a fan isn't needed unless there is just no air flow going to them at all. Similarly there is no need for rear brake ducts on the car either.
In some cases it is needed to run a brake duct fan, and there are a number of ones out there you can get. Like on our TransAm cars we needed them for the rear brakes and also the diff cooler as there was just no air flow to that side of the car.
If the air coming in is faster than the fan, then the fan becomes a restriction so you do have to watch that. In very extreme cases they will run water sprayers too, like the Euro Semi truck races.
For most guys doing 20-30 mins sessions a fan isn't needed unless there is just no air flow going to them at all. Similarly there is no need for rear brake ducts on the car either.
11-11-2010, 05:11 PM
#17
Safety Car
Thread Starter
It's happening in the paddock, you just discover it on the outlap. Best thing is to check them often between sessions.
FWIW, I've run more than a few sessions knowing I probably had a cracked rotor. 1: they get better as they get hot, 2: if you clamp down on the brakes hard enough, you barely feel the vibration. Hard to give up those prime late morning sessions.
FWIW, I've run more than a few sessions knowing I probably had a cracked rotor. 1: they get better as they get hot, 2: if you clamp down on the brakes hard enough, you barely feel the vibration. Hard to give up those prime late morning sessions.
