Cooling Fan CFM
Thread Starter
Heel & Toe
Joined: Oct 2025
Posts: 19
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From: Las Vegas
Cooling Fan CFM
Does anyone know the CFM rating on a stock C7 cooling fan ? I have tried to do some research but I am only finding either 500 or 600 watts and not actual output ratings.
Le Mans Master
Joined: Oct 2005
Posts: 7,002
Likes: 2,679
Well you can get an estimate by converting electrical power to mechanical power.
torque times angular velocity equals power just as voltage time current is. There is an efficiency factor usually .9 in converting electrical to mechanical. You can also estimate the angular velocity from current as they typically have a 1:1 ration times the efficiency factor.
600 watts is 50 amps (voltage is 12), and that means about 45 rad/s (assuming 90% efficiency) or 430 RPM. Of course that assume they need the 12 volts to make torque, which is about 9.72 Nm. If they don't need that much torque, they can "borrow" from it to get more angular velocity. I'm betting they are borrowing significantly from torque as 430 RPM seems low, but since they are proportional, if you need 1/10th the torque you get 10 times the RPM.
Back of napkin math, If the fan needs about 1 Nm to turn you'd get about 4000 RPM.
torque times angular velocity equals power just as voltage time current is. There is an efficiency factor usually .9 in converting electrical to mechanical. You can also estimate the angular velocity from current as they typically have a 1:1 ration times the efficiency factor.
600 watts is 50 amps (voltage is 12), and that means about 45 rad/s (assuming 90% efficiency) or 430 RPM. Of course that assume they need the 12 volts to make torque, which is about 9.72 Nm. If they don't need that much torque, they can "borrow" from it to get more angular velocity. I'm betting they are borrowing significantly from torque as 430 RPM seems low, but since they are proportional, if you need 1/10th the torque you get 10 times the RPM.
Back of napkin math, If the fan needs about 1 Nm to turn you'd get about 4000 RPM.
