White paint doesn't reflect heat, it reflects light, visible light to be precise, in this case, the light is a radiant source of heat. Darker colors absorb visible light radiation and convert that visible light to heat. Painting something white in a dark engine bay with only radiant infrared energy isn't going to do anything .

Physics Lesson!

The three main types of heat transfer are Convection, Conduction, and Radiation.

There are numerous things that control the properties of infrared absorption in the absence of visible light, but color isn't one of them. More important is material type, and it's convective and conductive ability.

Radiative Heat Transfer: It's all around us! Radio waves, Infrared light, Ultraviolet Light, Visible Light, Alpha, Beta, Gamma, X-Ray Microwave, all spectrums of EM radiation (Along with some lesser known forms like Neutron and other forms of Ionizing radiation). All of these forms of radiation, at least on some level, energize (heat) the things they pass through. Not really relevant for this explanation since we're talking about heat dissipation over heat absorption.

Conductive Heat Transfer: The transfer of energy by vibrations at a molecular level through a solid or fluid. Follows the law of heat conduction, Fourier's or law, which states that the time rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area at right angles, to that gradient, through which the heat is flowing. This, along with Convection, described below is pretty much how your IC works.

Convective Heat Transfer: The transfer of energy by fluid motion. In fluids (Yes, gases are also fluids, along with plasma's) heat convection takes place through both diffusion (The mixing of two substances from an area of high concentration to one of low concentration), and advection (Transport in a fluid).

A good example of convection is your oven at home. Most newer ovens have a convection mode, which basically just turns on a fan. It might sound silly, but your food will actually cook a LOT faster with convection turned on. The amount of heat present is the same (The oven is still set to the same temperature), but you've assisted the TRANSFER of that heat to whatever you're cooking, by utilizing advection. In this case, the air is the fluid that you're using as a transport medium.

This was probably way too complicated for a simple explanation, but I thought I'd just clear it up .

 

So in vis-versa if you painted it black would it make a difference??

 

Holy cow do you have time on your hands or what . Nick, go drive that car I'm starting to think you don't leave the house.

Longboard

 

If you drove around with no hood on, painting your intake box/IC white would reflect visible light rather than absorb it (thought since they're both likely silver anyway, I can't see this benefiting anything, unless it came black for some reason... ).

In this case radiative heat would be reflected, and your IAT's would benefit. In the real world, with a dark engine bay, painting your intake box or anything else for that matter is likely to do only one thing, limit the ability of that material to transfer heat via convection/conduction.

Even in the above no hood example it's likely that any benefits would be outweighed by the fact that you're trapping heat with the paint (Unless it was some kind of heat dispersant paint).

 

I drove around all day! Nothing to do, it's 10 pm on a Saturday . I'm eddujamakating (I was always bad a phonetic spellings) myself on Alaskan survival techniques (Yay for Discovery Channel).

 

Haha... I hear you on that one!!! I put in a pizza at 10pm and havnt left the forums all night except to watch the game... Damn I need those pistons!!!

 

saw this on horsepower tv . the paint was said to be a heat barrier. the white was said to have something to do with the paint itself and it's properties and not reflectivity . does it work ? they thought it helped a bit . but they did not paint the top as this would hurt dissipation .

 

and the effects on radiative heat dissipation would be very very small. But in theory this will work, to what degree? Who knows. Worth the time? Probably not.

Matt

 

True...
But it'll leave you with a trick looking black IC

 

Yea, I mentioned that if the paint had heat dispersant properties then it *might* help. It's doubtful that it's worth the trouble or expense though.