Hobbywing motor fan and heatsink alterations

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Toddys

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Arrma RC's
Under normal to extreme kraton bashing, I am experiencing higher than acceptable temperatures. 180 degrees for example. I just purchased the hobbywing ez run fan for the motor. in evaluating the heatsink that comes with it I am planning 2 cut off the sides, drill holes and wire zip tie it on. My thinking is that no matter the intention of a heat sink any additional contact with the motor that shrouds it will contribute to excess heat buildup via some sort of insulating characteristic. Additionally, I plan to cut out a square directly underneath the fan so that the air blows directly on the motor can and not into the heat sink. Since I am no engineer it appears again that there's an insulating quality to the heatsink and that by opening up for direct airflow onto the can I will be cooling more efficiently. The analogy is; do you cool your body by having a ceiling fan and being under the covers or on top of the covers? Unless I don't understand the principles of how a heat sink works I can't see how blowing cool air over the aluminum is going to be better than blowing cool or fresh air directly over the can. Anybody have any thoughts?
 
Under normal to extreme kraton bashing, I am experiencing higher than acceptable temperatures. 180 degrees for example. I just purchased the hobbywing ez run fan for the motor. in evaluating the heatsink that comes with it I am planning 2 cut off the sides, drill holes and wire zip tie it on. My thinking is that no matter the intention of a heat sink any additional contact with the motor that shrouds it will contribute to excess heat buildup via some sort of insulating characteristic. Additionally, I plan to cut out a square directly underneath the fan so that the air blows directly on the motor can and not into the heat sink. Since I am no engineer it appears again that there's an insulating quality to the heatsink and that by opening up for direct airflow onto the can I will be cooling more efficiently. The analogy is; do you cool your body by having a ceiling fan and being under the covers or on top of the covers? Unless I don't understand the principles of how a heat sink works I can't see how blowing cool air over the aluminum is going to be better than blowing cool or fresh air directly over the can. Anybody have any thoughts?

The purpose of a heat sink is to draw heat out of whatever it is attached to. This is accomplished with maximum clean contact between the two. This is allready compromised by the fins that are on most motors. A smooth can allows much more solid contact with a heat sink. There is also a compound that can be applied to the surface that promotes heat transfer between the two. Ideally there is no paint or coating on either other than heat sink compound. The large fins give more surface area for the heat to be transferred away into the coolant. (In this case it is the air) The fan is to move more air across the fins to dissipate the heat quicker. Simply blowing air over the motor with no or small fins
is less efficient. Actually you can even create too much coolant (air) flow that decreases efficiency due to the heat not being able to transfer to the coolant properly.
 
So essentially the compound is a vital component so as to avoid "gaps" between can and heatsink? Any recommendations?
 
Thermal grease increases the heat transfer between the heat sink and the motor. Its not required and most people don't use it but it would help. I don't use it because I can get adequate temps without thermal grease and thermal grease is very messy if you ever decide to remove the heatsink and I'm not sure how well it would hold up with water. Thermal grease is most commonly used between a computer processor and its heatsink, which is an environment that never has water.
 
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