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Okay, I know I'm an oddball for asking this one, but I am trying to build a "sleeper" (for those of you youngins, that's an old-fart term for a car with lotsa balls without the look of havin' 'em!!!). I can't accomplish this with a great, big aluminum i/c, now can I?
I've been told by a couple of folks that I shouldn't paint the i/c, as the paint will "insulate" the cooling fins and make it less efficient. This makes sense to me, but my question is just how much will a l i g h t dusting of flat black paint make for heat transfer? I've even thought of maybe taking one of them foam 6" wide rollers, emptying a bunch of flat black paint from a spraycan in a tray, and just rolling the front edge to get rid of that shine.
Whadaya'll think?
 

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someone here suggested a blue stain for guns to use on hardware and such. I'm thinking that would just stain the metal, not effect its cooling ability. Worth a shot maybe? Personally I wouldn't apply any kind of paint to it, something like a stain or anadizing though should be ok.
 

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FWIW... Stock MkIII I/c's are painted.... I've heard some say that thats why they are so in-efficient tho..
 

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No! There is a reason why those stock ICs are painted. Painting ICs black makes them 5 to 15% more efficient... Why do you think all radiators are black? The black paint radiates heat more evenly and efficiently so there no hot spots.
 

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Well, being curious I did a little searching to see what others had to say on the subject. It's seems as though a matte black surface is best for cooling.

I would think that any gains though would be lost by the paint/metal barrier. But being physics stupid, I don't know. The intercooler for my XR though is currently half black half metal from the previous owner. Best of both worlds.
 

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WadeT said:
No! There is a reason why those stock ICs are painted. Painting ICs black makes them 5 to 15% more efficient... Why do you think all radiators are black? The black paint radiates heat more evenly and efficiently so there no hot spots.
Although no one can argue with the laws of thermodynamics, the difference that paint makes on an intercooler is going to be negligible. Unless someone can show me some physical proof that it makes a significant difference to the intercooler efficiency, I cannot see how simple paint would make a difference such as you say. I've seen countless debates on whether painting the IC will or won't make any difference and I haven't yet seen any proof that it will make a significant impact. Unless of course you use really thick paint that clogs up the fins, that'll reduce the efficiency of the core significantly.

BTW most new cars are using plain unpainted aluminium radiators, not black.
 

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Now... How about mounting a fan to the IC. Wouldn't make much difference at high speeds unless it's mounted in bad position. But may help to keep the intake tempature lower overall.
 

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The stock intercooler is black for styling reasons. If its black and you look thru the grille you won't see it. Same reason the bottom of the rad support is painted black on the Mk2 and most cars. Although they are cutting back on this stuff these days to save costs. As far as painting it black to help cooling I doubt it. The main mode of cooling for the IC is conduction & convection (i.e. heat absorbed by metal and air blowing thru it). So having as few layers as possible between hot and cold side helps. For example the heat path is hot air -> aluminum core -> cool air or hot air -> aluminum core -> paint layer -> cool air. If you use a normal paint it will actually act like a insulator (not good). That is why they use a thin thermally conductive paint on radiators ( which helps for corrosion on copper rads). The only way I could see the paint helping is if it made the air more turbulent going thru the core (which is probably very unlikely to be significant). Painting something black helps with radiation (black body). Usually radiation heat transfer is minimal on small objects that are relatively cold and small.
 

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Right on Aaron. Excellent description. Paint will only reduce conductive and convective heat transfer for an IC. Blackbody thermal radiation won't be significant.

Flyin', if you really want the stealth look, you could compromise by just painting the front surface with a roller as you suggested. Just make sure to use a roller that is very nearly dry with only the very least possible amount of paint on it. That way it won't run down into the openings between the fins. You just want to get rid of that "shine" on the very front edge of the fins.

Or, you could add some mesh to the openings under the airdam and paint the mesh black. That would help to hide the IC and would also help to protect it from damage from birds/rocks/flying debris. Eavestrough/gutter guard works well and is cheap. Available at hardware stores.
 

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I've yet to see any before/after testing for painting intercoolers. Anodizing would be a good choice, as would the use of a thermal dispersant. I've also not seen any testing of thermal dispersants on intercoolers, so it, like many other attemtps to try something new, can be a gamble.
-Aaron
 

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There is maybe 5% of the cooling done on the frontal-facing surfaces. Everything else is done between the fins, of which will not be painted thickly. I would see no problem in dusting the visible parts with some flat black...

-BillyM
 

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Discussion Starter · #16 ·
Woohoo! I opened a can of worms here, eh? Well, I'm gonna try the roller theory, and yes, I'll make sure it's very dry before rolling it! Maybe use gunsmith bluing instead of paint!
Intercoolers are not cheap, and I'd be really aggravated w/myself it I were to ruin this one just because of paint!
I thought about some screen or mesh to cover the holes of the bumper, but don't really like the look of screens over the openings. Even had a suggestion of putting screen right over the front of the i/c, but don't think that'll hide the shininess enough and may restrict the airflow a tiny bit (it's amazing how much air is reduced when a screen is put in front of a fan!).
I'll keep everyone posted once I get done w/the project! Not sure when I'll be starting on the engine swap, but hopefully it will happen before the end of the year!
Thanks folks for all the responses!
Chris
 

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Im not sure what IC's are made out of, but... guns are blued with this stuff that basically oxidizes the top of the metal a blackish blue color, if your IC is made of steel this could be another approach to getting your IC looking black, you can get liquid bluing at any gunshop/walmart/big 5
 

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Alodizing's (not anodizing) the answer. An alodized aluminum surface
conducts electrically while anodizing doesn't. Everything known to man
(and women too) that conducts electricity better also conducts heat
better except diamonds, which btw have 5X the thermal coductivity of
copper which is 2nd best conductor after diamond. Last, and most
important, maybe. U can alodize almost any color u want including
BLACK. hth
 
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