No.

It will not.

Get it right.

-bill

 

Well thermodymamicists call the theoretical perfect ratiator a "black body" anything less than perfect (real) is a "grey body".

 

Don't make me go dig my old thermodynamics text out and explain why that phrase has nothing to do with paint color. Your should first consider your earlier statement:

and consider why is it wrong.

-b

 

Anyway, I really don't think the colour has much impact on cooling anyway, since radiation probably won't be the most prevelant method of heat transfer, and adding the paint will decrease the rate of conduction of heat to the surface through the extra thickness and thermal resistance of the paint, and through the contact resistance at the interface between the metal and the paint.

 

Think of this. What color was the oil pan on you rotary engine, when it left the plant? Black. Why did they paint it black? They painted it, to prevent rust. They painted it black, to help draw heat out the oil. Air flow under the car then cooled the surface of the pan, so the process could continue.

 

As long as the paint is in fact black in the infrared spectrum (it may be possible for it to be black in the visible spectrum and white in the infrared spectrum) it will absorb and emitt most infrared light whereas white will simply reflect most of it. I don't see why this is incorrect. I is consistent with everything I have ever read or learned on the subject. I never studied thermodynamics though, so perhaps you can enlighten us by explaining why it's wrong and back it up with data or facts.

Or maybe I should just say no, actually you're wrong, and that can be sufficient just like your post

I agree though that most of the heat is being dissipated through convection and not radiation so it probably would hardly make any difference anyway. In that sense the material selection (how well it conducts heat) is probably much more important. How did we even get on the subject of color?

 

If only you had stopped there, but nooooo.
Black paint (or any other color for that matter) on the outside of the oil pan does not help (nor hinder, nor affect in any way) the temp of the oil within.
In fact, the oil pan is not considered a part of the oil cooling system at all...if it were it would be finned (to increase surface area) and more care would have been taken to duct fresh air around it.
This is true of calipers as well.
*From the Wilwood website...*
"A durable black anodized finish is standard on most models, with some available in a polished finish for show car applications."
Note that no claim as to temp reduction/optimization is made, only that the finish is "durable". This follows several paragraphs detailing the steps taken to deal with heat issues- special seals/isolator pads/internal pathway optimization/ect....you'd think that the exterior finish would be listed as well if they could support the claim, but they can't so the finish is advertised as "durable" only.
Go ahead and paint your calipers any color you like, or leave them bare...ultimately it won't make a damn bit of difference.

 

It's interesting to note however that they anodize the caliper, not powder coat it or cover it with a layer of ceramic paint. Anyone know if any of the other aftermarket brake companies actually paint or coat their calipers in some way other than anodization?

 

Many aftermarket calipers are powder coated. As has been stated, the trick is to keep the heat out of the caliper in the first place. The heat that does get to the caliper will be sinked out to the spindle much faster then to the air.

Paul

 

this is rather amusing... i dont think it really makes a difference what color they are or if they are even painted

 

I dont think its really worth worrying about on a street car =P

 

color has no bearing on heat caused by friction. Brembo,endless, Wilwood, Project Mu all paint their calipers.

 

Here are my rz calipers with a fresh coat of epoxy paint for all the engineers here!

 

We're not arguing about colour affecting heat caused by friction, we're arguing about the rates of heat dissipation through radiation being affected by the colour.

 

and you actually think the color of an object, where light is not invloved, is really going to effect its ability to dissipate heat?

also... I've never seen a 'high temp paint' that was rated at over 500 degrees... if you're going to be using your brakes to the point where you might be worried about heat dissipation this seriously, the temp of your brakes is going to be much higher than 500 degrees.... at which the paint will burn off, completely killing its 'ability to improve the heat disipation' of the object it is on.
so maybe with some sort of powder coating or anodizing or something... ? I don't know anything about those.... but even so, if color made even the slightest bit of difference, don't you think aftermarket brake companies would all paint their calipers the same color in order to improve their heat dissipation abilities?

how did this thread seriously last 3 pages on topic?

 

If all performance companies cared about was performance, then why do you get cross drilled rotors on countless performance cars (just one example)?

I don't think it makes that much difference, but there may be some. It'll probably matter more on what kind of coating you use, I'd immagine annodizing would be best, as it's just a layer of oxidized aluminum, not a seperate coating.

The point I was making is that he totally missed what was going on and called us morons for doing something that we weren't doing.

 

Actually, radiant heat is just electromagnetic radiation (i.e. light) at a slightly lower wavelength. So light is involved (or more accurately, em radiation is involved and therefore has exactly the same properties as light). Colour does have an impact on absorption and radiation of heat (and light), but the effect on a brake caliper is miniscule in proportion to convective cooling and is insignificant. Otherwise, Porsche wouldn't paint its race calipers red.

 

thread is confusing because people are getting mixed up between the two:

1)are we talking about the calipers radiating (SP) off its heat
or
2)the caliper absorbing heat

first off, if anyone's post here mentions they want to make the caliper absorb less heat, this really isnt possible, I dont know how hot the temerpatures get, but im sure its hot enough to reach the point where it will allow itself through whatever coating you have on your calipers. Heat is energy, it cannot just dissapear, it doesnt have many places to go, and it will choose the more eaiser conductor of whatever your calipers are made of over the air.

secondly, putting a coating on your calipers will increase the complete area of it, in result, the heat should dissapate at a lower concentration throughout the caliper,

this isnt the only variable:

also, putting a coat as I said increases total area, in result the heat will have to travel more distance to completely get off the caliper, in result, caliper retains heat longer

another variable

if caliper is larger once again the whole heatsink theory does apply, heat will be on the caliper longer, but, will not be as hot near the pads because the heat is no longer concentrated...

I can sit here and think of a hundred more variables, its all about plyaing a balancing game, which requires extensive experiments and data. We will NOT be able to find that unless we have thousands of dollars of equipment and shitloads of spare time, so if anyone wants to test this, with every single possibility, please do so, lol.

If it were as simple as painting a caliper a color to get more performance everyone would be doing it, and trust me, someone has thought of it before, with the population massively expading every year, its harder and harder to make new performance aiding discoveries, or more commonly, like in this case, just too damn time consuming and COSTLY.

was reading through and waiting for someone to bring this up. Simply put:

Color only effects thermal energy transfers from light (ie: sun), not thermal energy transfers via friction (ie: calipers and pads).

didnt have the time to read through the rest of the thread...

 

Heck, even AutoZone carries High Temp Paint rated to 1200F (look up the Dupi-Color brand).

 

It's okay to disagree and argue, but please no trash talking eachother. Thanks.

 

maybe me meant celcius? did a conversion, works out to 932F, pretty close...

 

Paint the calipers black as they will radiate more heat so to speak. The difference will be negligible. Ducting fresh air to the brakes will provide a greater benefit than painting the calipers but every little bit helps.

 

You guys are forgetting thet the paint will also act as an insulator, both by it's own thermal resistance and by the thermal contact resistance. I strongly feel that any possible small gains from better radiation will be more than offset by the increased resistance slowing conduction to the surface, slowing convection.

http://en.wikipedia.org/wiki/Thermal...ct_conductance

 

I can't imagine it makes much defference either way. If you went and powdercoated or painted your downpipe, regardless of color, would it significantly affect underhood temps? I doubt it unless it was a thermal coating of some kind.

 

god this is stupid... how can you still be seriously discussing this?

next its going to be, "what color and how many coats of paint should I put on my engine block to get the best cooling?"

its ******* paint, on things that get well over 1k degrees (brakes)... its not going to make the 'slightest' be of difference, whether you're talking about color, or insulation.