Painting an engine: How does it affect cooling?
- lgeis
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- Wrapped around the axle.
I'd think the paint would produce some insulative effect...and that the unfinished (rought, unpolished) metal would cool much better.
Gal. 2:20!
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- bountyhunter
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1979 KZ-750 Twin
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- bhardy501
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1980 KZ1000B LTD
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- Jack
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79 KZ 1075 MKll
79 KZ 1500 MKll dragbike
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- Bad Dad
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Paint does reduce heat transmission between the metal and air, I don't know exacty how much. Can't be a huge effect as long as it's thin. With aluminum, you can anodize it to color it and not degrade heat transmission and if it's the right color, it may improve it very slightly.
I've always heard that black transfers (or actually absorbs) heat the best.
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- hugo
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Most of the heat dissipation is done by convection. Air flowing throught the fins, not radiation.
Heat transfer from metal to paint is not very good, but heat transfer from metal to air is even poorer, so air can't keep up anyway even with the paint.
A black body is best dissipating and radiating heat, but only in the infrared spectrum not in the visible spectrum, (what it looks like to us), Nevertheless manufacturers paint engine in black when it comes to cosmetics, so when it comes to only radiation, (motorcycle is not moving), a black engine maybe be, theoretically, a little better dissipating heat. But obviously not enough to make manufacturers rush into painting all air cooled engines in black.
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- bountyhunter
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Correct. There is a heat radiation effect called "black body radiation" which is enhanced by the color being darker, ie black is best for that effect. I suspect the effect is very small overall.bountyhunter wrote:
Paint does reduce heat transmission between the metal and air, I don't know exacty how much. Can't be a huge effect as long as it's thin. With aluminum, you can anodize it to color it and not degrade heat transmission and if it's the right color, it may improve it very slightly.
I've always heard that black transfers (or actually absorbs) heat the best.
1979 KZ-750 Twin
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