Why aren't all engines black?

[Headrope]

The color black dissipates heat, right?
Any reason to think that painting an intake manifold - hell, maybe the whole engine - would not keep it running cooler?

[skip68]

Well, if it was all black it would be hard to see any oil leeks.

[Ghoste]

Didn't Petty use to run all his blocks without paint, claiming they ran cooler that way?

[Chryco Psycho]

most engines are black now
any paint will insulate to some degree

[8WHEELER]

When I rebuilt the engine in my father-in-laws S10 I talked him into panting the engine black. He did
not care what color it was so I went with the black to help dissipate the heat, that was 10yrs ago and
about 100k miles on it now and no problems. If you don't care what color it is it can't hurt that's for sure.

Dan

[bull]

I don't see how the color of the paint matters when it comes to friction-generated heat in an engine? Color has to do with the amount of heat absorbed or reflected by sunlight but it would seem to me that only the chemical makeup of paint would have anything to do with the dissipation of heat. Any coating of paint is going to hold some of the heat to the metal.

[4402tuff4u]

I don't see how the color of the paint matters when it comes to friction-generated heat in an engine? Color has to do with the amount of heat absorbed or reflected by sunlight but it would seem to me that only the chemical makeup of paint would have anything to do with the dissipation of heat. Any coating of paint is going to hold some of the heat to the metal.

I agree with Bull. Why would the color of paint have anything to do with the dissipation of heat? I know light colors reflect heat and dark colors absorb heat from sunlight energy, but from an internal heat energy source??

[Headrope]

This question came about because an old-timer that I trust told me that "back in the day" he painted his engines black because the heat dissipated better. I questioned him, thinking any paint would insulate. His suggestion was that the color black absorbs heat; so by painting the block black it would absorb heat from the motor - therefore causing it to dissipate heat quicker. He went on to suggest that is a reason most headers came out of the box painted black, before everyone got excited about chrome.

At the same time, though, I'm cynical: If it's true, why weren't all engines black? Then I stopped and thought about it: most new engines are painted black.

Someone needs to start a television show like "Mythbusters" - but for the Speed Channel, and sort out theory from what's plausible. I think I'll contact them.

[bull]

I did find this: http://home.howstuffworks.com/question32.htm

[Nacho-RT74]

IMHO ANY paint wouldn't dispate the internal heat as stated by bull and 4402tuff4u. would be like seal the heat inside the enamel coat. Paint is just for looks and protect from rust.

what it could be true is reflecting the external heat. In that case you would need to paint with lighter colors, not darker.

[Nacho-RT74]

Ok after read that link we could try to call to Mythbusters.

in Engines maybe with we win painting black, we could lost with just the paint coat like a seal... maybe

Or maybe the option it could be... if you paint the engine why don't do it with the best color as possible to win some, like black

[Blown70]

This question came about because an old-timer that I trust told me that "back in the day" he painted his engines black because the heat dissipated better. I questioned him, thinking any paint would insulate. His suggestion was that the color black absorbs heat; so by painting the block black it would absorb heat from the motor - therefore causing it to dissipate heat quicker. He went on to suggest that is a reason most headers came out of the box painted black, before everyone got excited about chrome.

At the same time, though, I'm cynical: If it's true, why weren't all engines black? Then I stopped and thought about it: most new engines are painted black.

Someone needs to start a television show like "Mythbusters" - but for the Speed Channel, and sort out theory from what's plausible. I think I'll contact them.

UV rays,  black will absorb.... This is under the hood and will not make a lick of difference..... wanna get rid of heat.... ALUMINUM

Tom

[Ghoste]

I think if there were any real benefits to black, you'd see all the engurance type engines such as NASCAR going that route.  Any field where a degree or two is the difference between winning or dnf will take advantages anyplace they can.  Even if Petty's no paint idea was really beneficial I think it would be used across the board.  After all, they don't need to worry about rust or appearance.
Paint it any color you want and sleep soundly.

[4402tuff4u]

I'm now wondering if that is the reason why the "SR-71 Balckbird" super sonic spy plane was painted black and why the belly on the Space Shuttle is painted black. Hmmmm......there could be a correlation between the absorption and emission of heat in different color materials after all......now I wonder if that's the reason why barbeques are also black!  Learn something new everyday. Must been sleeping through that chapter during physics class. 

[RD]

i dont know about this, i call BS on the black emitter/absorber concept being best.  Definitely a mythbusters project for sure.

[Ghoste]

The space shuttle and the SR-71 are operating in very different ways and environments than this, not to mention utilizing special paint formulations that are applied for a practical purpose beyond appearance.  No one has denied the physics behind this, we are disputing the usefulness in this application.

[4402tuff4u]

i dont know about this, i call BS on the black emitter/absorber concept being best.   Definitely a mythbusters project for sure.

Actually is a proven fact. See the attached formula.

http://www.efunda.com/formulae/heat_transfer/radiation/blackbody.cfm

[Nacho-RT74]

Just a note:
Space shuttle and SR71 are not ( beside the engines/jets/rockets ) creating heat from inside as our engines... however they are painted black and theorically then they are GETTING more heat if the black paint absorbs.


Anyway, is true, our stuff is not at extremal conditions to make A BIG difference to worry if you pait in one or another color...

[defiance]

It's definitely true, but may not apply here -- Black engines WOULD dissipate (sp?) heat better.   That's scientifically proven (or not disproven, if you're big on the scientific method ).   A black *painted* engine, however, may or may not.   The *paint* will dissippate heat better because it is black.   However, the rate of heat transfer from the engine to the paint will probably limit the effectiveness of that, since the heat has to dissipate from the block to the paint, then from the paint to the air.  

Besides, most engine heat dissipation occurs in the coolant system, doesn't it?

However, a black *anodized* aluminum block (or probably more relevant, a black anodized aluminum radiator) would dissipate better than its silver counterpart, since the anodization is actually a part of the aluminum.   I have to wonder, however, if it is enough to bother with

*edit* - also of consideration is that some *materials* dissipate heat better than others.  What you gain by changing to black, may also be mitigated if the chemical composition of the paint is worse at heat transfer than whatever metal your particular block is made of.

[BigBlackDodge]

It's definitely true, but may not apply here -- Black engines WOULD dissipate (sp?) heat better.   That's scientifically proven (or not disproven, if you're big on the scientific method ).   A black *painted* engine, however, may or may not.   The *paint* will dissippate heat better because it is black.   However, the rate of heat transfer from the engine to the paint will probably limit the effectiveness of that, since the heat has to dissipate from the block to the paint, then from the paint to the air.  

Besides, most engine heat dissipation occurs in the coolant system, doesn't it?

However, a black *anodized* aluminum block (or probably more relevant, a black anodized aluminum radiator) would dissipate better than its silver counterpart, since the anodization is actually a part of the aluminum.   I have to wonder, however, if it is enough to bother with

*edit* - also of consideration is that some *materials* dissipate heat better than others.   What you gain by changing to black, may also be mitigated if the chemical composition of the paint is worse at heat transfer than whatever metal your particular block is made of.

Now if we can just figure out how to paint the water black............hmmmmm


BBD

[Ghoste]

I still say that with the budgets to experiment and the pressure to win in NASCAR that those guys have done all the tests that apply to real world use and that if their were any gains from engine external coatings to be had, they'd be doing it.
I'm not saying that measurable results couldn't be proven, just that any appreciable gains have been too small to date to make it worthwhile using.

[HeavyFuel]

I think if there were any real benefits to black, you'd see all the engurance type engines such as NASCAR going that route.   Any field where a degree or two is the difference between winning or dnf will take advantages anyplace they can.   Even if Petty's no paint idea was really beneficial I think it would be used across the board.   After all, they don't need to worry about rust or appearance.
Paint it any color you want and sleep soundly.

I just went thru some photos I took in the Kansas garage back in 2002.  Engines from Evernham, DEI, Petty Enterprises, Hendrick were all unpainted.  That goes for the blocks, intakes, water pumps, everything. 

Tony Stewart's block was black.

[Runner]

now, if i paint my oranged engine black will it run cooler or will i need to strip the paint.  and if its black and in a roadster will it still be cooler?.   


   im bettering that engines get painted black from the factory to hide oil leaks--- and save on warrentee claims.  if it helps id bet it isnt much. 

[Johnny SixPack]

    im bettering that engines get painted black from the factory to hide oil leaks--- and save on warrentee claims.   if it helps id bet it isnt much.  

That's sounds like it's dead on.

With many new engines the black block matches the black plastic accouterments.

[Ghoste]

Or contrasts the cool gray "Hemi" spaceship on the top of some?