Painting Aluminum Radiator and Intercooler

[Patrick]

I was thinking about painting my Aluminum Radiator and my Intercooler a Flat Black. I want them to 'disappear' behind the grill:



1) Will painting them cause any loss in cooling efficiency?

2) What type of paint would you suggest?

Thanks,
Patrick

[dipren443]

I was thinking about painting my Aluminum Radiator and my Intercooler a Flat Black. I want them to 'disappear' behind the grill:

1) Will painting them cause any loss in cooling efficiency?

2) What type of paint would you suggest?

Thanks,
Patrick

This one should get interesting. There are two schools of thought here. I am on the side of the fence that chooses the not so obvious answer and I will substantiate my opinions. You will actually increase the ability of the (I will call them heat exchangers) two by increasing surface emissivity. Emissivity is defined as an objects ability to emit thermal radiation. By increasing the emissivity, the heat exchangers will actually be able to dissipate heat more efficiently. But, painting is not a suggested method. Anodizing is preferred. Paint also acts as an insulator. A thin coat may be ok, but anodizing is the way to go.

An excerpt from a paper discussing heatsinks as the concept is the same:

Radiation requires that the surface has the maximum emissivity of heat, and this means that its colour is important. Shiny gold anodised heatsinks might look great (if you like that sort of thing), but are hopeless at radiating heat. It's no accident that the radiator in a car, or the condenser on the back of a refrigerator is matte black - not chrome plated and shiny. Matte black heatsinks are the best for radiation, and will have a significantly better thermal resistance than any other. Use of paint is to be avoided however, unless kept thin and even, as a thick layer of paint acts as an insulator, reducing the ability of all those unwanted therms to get out into the air.

This is one of the reasons that aluminium is so popular as a heatsink material - it can be anodised, and black dye is then introduced into the porous layer of aluminium oxide. This is far thinner than any coat of paint, and is very effective. Copper is actually a far better conductor of heat, but cannot be anodised, and its colour is such that it is a naturally terrible radiator. Such is life. Oxidised copper (kinda, sorta like anodising) is passably effective, but rarely used due to its cost. Table 3 shows the "emissivity" of various surfaces. This is a measure of their ability to emit infra-red radiation (heat), and a figure of 1 is as good as it gets for a passive heatsink (i.e. no heat pumps or the like). This list is not exhaustive, but is a fair indicator for the most common surface treatments.

[Patrick]

OK....on the radiator I only wanted to paint the surface area that is exposed through the radiator support on the grill side. All surface areas of the intercooler would probably need to be blacked out.

Is anodizing an economical alternative?

[dstryr]

Instead of painting that why not just make a thin piece of metal to go infront of it...hidding it from outside view/

[onebad2]

Painting should be no problem,

be sure to get them sanded very good, and use a good exopy primer. and them any automotive black paint your looking at should be fine.

This is how I did my car,






Paul

[sellersrodshop]

another option to the epoxy primer would be to use PPG wash-primer (1791 primer/1792 catylist). it is a much thinner etch primer that might dissipate heat better. i've used it on everything i've built for 10 yrs now with excellent adhesion results.

[x2cstang]

I would suggest using a good metal prep first.
Por-15 makes a product called Metal-Ready which is good for what your doing.

PPG makes the following Aluminum Cleaner DX501 & DX503: Aluminum Conditioner That's in their Deltron line

USe this stuff first on the bare metal.

[Patrick]

I stopped by a local industrial metal finishing business today and luckily the owner was kind of a car nut. They don't do much single run, small stuff but he liked the idea of anodizing the intercooler black. He quoted me $80.00 and said it would take a couple of days. I saw some of their finished work and it looks very nice. I am going to drop it off Monday and I will post the results.

Patrick