cfm airflow through brake ducts?

TommiM · Oct 31, 2009, 11:19 PM

Has anybody actually measured or calculated how much air is typically being going through those aftermarket ducts during track use? Reason I ask is, could it be more efficient to mount an electric fan, like one of those electric supercharger thingies, to the end of the brake duct? I have been wondering how effective this could actually be.

flyingscot · Nov 3, 2009, 07:23 AM

Quote:

Originally Posted by TommiM

Has anybody actually measured or calculated how much air is typically being going through those aftermarket ducts during track use? Reason I ask is, could it be more efficient to mount an electric fan, like one of those electric supercharger thingies, to the end of the brake duct? I have been wondering how effective this could actually be.

ive been thinkin about that for a while,you can buy the inline fans and place them alot closer than an air inlet on your bumper and keep the ducts a lot shorter, the fans arecheap but im just not sure how effective they would be,i have all the stuff in my garage ready to go but cant decide which way to go yet,im also on socalevo.net,pm me if you come up with something

TommiM · Nov 3, 2009, 08:59 AM

Quote:

Originally Posted by flyingscot

ive been thinkin about that for a while,you can buy the inline fans and place them alot closer than an air inlet on your bumper and keep the ducts a lot shorter, the fans arecheap but im just not sure how effective they would be,i have all the stuff in my garage ready to go but cant decide which way to go yet,im also on socalevo.net,pm me if you come up with something

http://www.hvacquick.com/products/re...es-Inline-Fans

something like this, but maybe in a 2.5" or 3" diameter is what I was looking at. When I get more progress on this I will keep you posted.

flyingscot · Nov 6, 2009, 06:47 AM

Quote:

Originally Posted by TommiM

http://www.hvacquick.com/products/re...es-Inline-Fans

something like this, but maybe in a 2.5" or 3" diameter is what I was looking at. When I get more progress on this I will keep you posted.

ok dude,heres what i decided to do,i already have my 3"silicone hose ready to go so i was looking into fans and those ones in your link just did not seem tofloat my boat,not enough air flow s i started searchig,found a place called the fanman and bought two 7.5" fans,ill makea custom shroud so i can reduce to 3"but the fans were spal fans with 420 cfms and they were $53 each,if it doesnt work out like i hoped i havnt dumped excessive cash at it,ill keep you posted

TommiM · Nov 6, 2009, 10:21 PM

7.5" fans seem like it would take up alot of space. Where are you mounting the fans, in front of the fender liners? the inline fans dont have near the cfm as those, but fit in small spaces... http://www.hrpworld.com/index.cfm?fo...action=product

-- I wonder if it would cause damage due to thermal shock if,instead of an air cooled duct, attach a water injection nozzle (very fine mist) close enough to the rotor to cool it down that way? Just trying to think outside the box.

here is some info I found.
http://www.opentracking.com/water_cooling_brakes.htm

**SmikeEvo** · Nov 7, 2009, 05:11 AM

I would guess thermal shock by applying a continuous water spray to the rotor area.

Ill have to look for the equation to measure flow through a tube.

nothere · Nov 7, 2009, 06:43 AM

if you really want to do this a ducted fan and electric motor will give you plenty of air. its not uncommon to fly an electric motored ducted fan plane at over 100mph

2 things, the little motors will have a limited life.
running them when the car is stopped will tend to cool one end of the rotor.

xtnct · Nov 7, 2009, 07:40 AM

What problem with your brakes are you trying solve? What brake components are you overheating?

Did you try all the regular and already proven stuff to solve your issue? Is your current ducting mated to a proper mount that directs air into the center of the hub? If no, I suggest choose that route first.

Did you try changing your driving style?

My approach is to keep things simple - fewer things to break.

Back to your CFM question... any 2" ducting just diameter wise does not flow enough air to fully and properly cool the brakes. It is better than nothing, but not optimal. On street cars, fitting anything bigger than 2" is not really practical. Optimal brake duct diameter is anything over 3" and 4" for some big discs.

TommiM · Nov 7, 2009, 01:54 PM

Quote:

Originally Posted by xtnct

What problem with your brakes are you trying solve? What brake components are you overheating?

Did you try all the regular and already proven stuff to solve your issue? Is your current ducting mated to a proper mount that directs air into the center of the hub? If no, I suggest choose that route first.

Did you try changing your driving style?

My approach is to keep things simple - fewer things to break.

Back to your CFM question... any 2" ducting just diameter wise does not flow enough air to fully and properly cool the brakes. It is better than nothing, but not optimal. On street cars, fitting anything bigger than 2" is not really practical. Optimal brake duct diameter is anything over 3" and 4" for some big discs.

I havent seen alot of data showing that brand x brake ducting lowered temps by this much. Even less have I found info from the makers stating how much airlfow one can realize at speed with them (not dd around town, but on a racetrack). So what I was looking at would be ,what I would think is a more efficient way to do it. using a blower to push air into the duct. I am not trying to come across as saying that the kits out there dont work (ams,forge,etc). All I was looking at was what else could work efffectively.
I am curious as to how much air is actually going through those ducts during track events. I guess it must pressurize fairly easy to need a minimum 3" duct.