Background:
The idea behind brake spraying is rooted firmly in thermodynamics. As water
changes phases from liquid to gas an enormous amount of heat energy is absorbed.
We want to use the heat absorbing properties of the water to gas phase
transformation to cool our brakes.
The idea is to get a fine mist of water into the cooling vanes inside our
rotors. The fine mist will evaporate and cool the rotors as it travels through
the vanes. We want to avoid a constant stream of water that may come in contact
with our rotors and cause warpage. By spraying a fine mist we will ensure that
we expose the maximum surface area of the water sprayed at the brakes giving us
the best possible distribution and evaporation of the water. For this reason,
nozzle choice and pump pressure are very important.....better atomization of the
water will make the entire braking system work better.
Application:
Brake spraying can improve the
cooling of ANY brake system that uses a vented rotor. Many of you probably saw
the Tran-Am race this past weekend won by Bobby Archer. Those big heavy cars all
use brake sprayers to assist cooling.
I would NOT suggest using this for any solid rotor. Spraying water on one side
of a rotor can cause uneven pad wear, rotor warpage and other problems.
I have a 94 AWD Talon which is under braked from the factory. In the past I
would have to have my rotors skimmed after every event due to warpage. Since
installing brake sprayers, I have not had to skim the rotors one single time
after four events (8 track days) despite using them much harder than I have in
the past (because my brakes work better). I am buying an upgraded brake kit for
my car in the near future (about two hours:-)) and I will continue to use the
sprayers.
Tech:
I do not know how different cars
are laid out but I will be glad to discuss how I set up my system.
Here is a parts list for my system and where you can buy the stuff.
1 Shurflow 100 psi "on demand" pump $80
[http://www.pro-spray.com/sprayer_pumps.htm]
1 30 amp automotive relay $5 [Radio Shack]
1 lighted toggle switch $3 [Advance Auto]
Reservoir which is a 2.5 gallon plastic fuel can from Home Depot and
associated mounting hardware.
2 1/2 MT to 1/4" (or 1/8") NPT adapters [Home Depot]
Mounting hardware for pump and nozzle brackets [Home Depot]
The next 8 items should be purchased from Brad Schaeffner at George's
imports 816-333-6582.
Adequate length of 4mm nylon line
1 Aquamist normally closed water solenoid $60
1 accumulator (Brad sells an accumulator with an instant disconnect fitting
in place) $40
2 instant disconnect "T" (4mm tube) $5 ea
2 Aquamist 0.7mm nozzles $16 ea
1 Tap for nozzles $26
1 Aquamist filter (must use) $12
Adequate length of 6mm line to go from the reservoir to the pump. The
filter will go in this line.
2 1/4" (or 1/8")NPT to 4mm tube adapters (instant disconnect on tube side)
You will also need the following.
Misc electrical parts (M/F connectors, butt connectors, crimpers, ring
connector) Red and black primary wire
Note: I used an unusually large reservoir because I spray my throttle
body, intercooler and radiator as well. A 1 gal reservoir should be more than
enough for a 30 min session.
Electrical ....
The pump and the solenoid are wired separately.
The first thing that needs to be done is to get power to the pump. I got 12V
power from the rear of my car from the fuel pump (I have a custom fuel pump
rewire done that I easily tapped into). I wired directly from the fuel pump
power to my Shurflow pump and then to ground. This energizes the pump whenever
the car is running. The pump will shut off whenever it builds 80-100 psi
pressure. This normally takes about 3 seconds when using an accumulator.
The wiring of the solenoid is a bit more complicated. I again took 12V power
from the fuel pump wire. The wiring went as follows. FP wire ---> 30 AMP relay
---> Aquamist solenoid ---> toggle switch ---> ground. Then I tapped into the
positive wire for my right rear brake light and sent this power to the solenoid
as the "trigger". This wiring combo means that the water spray solenoid can only
be activated when the car is running.
Tubing.......
Run the 6mm supply tube from your
reservoir to the filter and then to the pump. From the pump run 4mm nylon tubing
to the water injection solenoid ---> instant disconnect "T" ---> the two spray
nozzles. The last step is to cut the 4mm tubing somewhere between the pump and
the solenoid and insert an instant disconnect "T". Attach the odd end of the "T"
to the accumulator.
Finally you need to attach your nozzles to something so that you can point your
nozzles at the center of your rotor. Be creative. I made small brackets and
attached them to what is left of my dust shields. Then I drilled 1 hole in the
dust shields to allow the water through. The nozzles have these oddball metric
threads. You'll need to buy a tap from Brad if you want to mount them using the
threads on the nozzle.
I also protected the nylon line with a 3" long section of vacuum tubing. I
simply slid the vacuum tubing over the nylon. This buffers the nylon from the
extreme heat. I haven't had ANY problems with either melting all season.
Scott
Feel
free to email me with questions......
awdracer@yahoo.com
http://www.opentracking.com/scott_willard.htm
