Jeff Spitzer wrote:

Just do the math.  It will save you much grief and agony of building this
useless device.  Q=m*c*delta T

Q=the heat of the horsepower absorbed
m=the mass of the brake rotor and pads
c=the specific heat of the brake rotor and pads
delta T=the temperature rise

My guess is that a "truck rotor" will be good for no more than 10 seconds
at 150 hp.  Certainly not enough time to obtain a stable dyno reading.
What's that smell?

O.K. Fine.   Here goes.
c=.10 btu/lb*deg F for cast iron
Q=150 hp = 6366 BTU/min
Use 1000 deg temperature rise
Use 15 lb for mass of rotor and pads

Damn, I was wrong.  That gives 14 seconds.  And I thought it would be less
than 10 seconds.  As for using water to get the heat out: It would take a
proper heat transfer solution to work i.e. proper flow and surface area.
There is not enough surface area on a disk to hose it down at high HP and
have it not overheat.

Jeff Spitzer

Your temp rise is too low Jeff. Those disk run 1600 F or more in road racing.
Bright orange at night. You have lots of radiation from the surface of the
disk. It takes about the same HP to stop a road racing car as it does to
accelerate it roughly. 800 HP from the engine 200 HP from each brake
disk. Very roughly. Usually about a four inch diameter duct for each brake
pumping air into the hollow disk at an average 100 MPH speed will keep the
disk brakes working on a 800 HP road racing car for 12 hours or so. Roughly.

Paul Lamar

Let me know how it goes.

Jeff Spitzer

 
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