im a bout to put a intercooler in my dat are they left it alloy for looks or is there a reson for it ?
and black would bee better for heat lose ??

I always wondered about this myself Why would the factory do them in black and not leave them alloy. Maybe all the after market ones are left alloy for the bling factor???

heres some theory >when i built my computer. I linished and buffed the surface of my alloy heat sink for my cpu .this gave a greater heat transfer across the face of the heat sink thus having a better transfer of heat.....................
If i were a black t shirt in the sun my body heat will be geater than wearing a white one ...........
So polishing the inter cooler would be the best option ............

....but black absorbs heat

but factory has always painted radiators in black/matt black for the best radiant heat, ie it radiates heat greatest. that is what i was always taught

shiny stuff refects light, and will probably also reflect more heat....so if your worried about the heat from the outside polished is good

and if you paint it then the heat will have to be transfered through the paint also....so less stuff on the outside of the cooler the better

mercedes coolers are left unpainted from factory im pretty sure(vito ones definatly are)
and i think the XR6 turbos may also be unpainted

id only worry about painting the cooler black if i was trying to hide it

doesn't matter at all.

air-air intercoolers work by convection on either side of the intercooler surfaces and conduction through the material.

the surface coulour will only effect radiation properties of the surface.

however a thick coating of paint could decrease efficiency by acting as an insulator.

Most radiators,coolers etc. are painted by the factory for a good look factor and also to help protect the cores from the OUTSIDE elements in a daily use situation.

Black is used as it covers a multitude of minor inperfections,is cheap and covers very well.

Ask yourself one question:How many competition vehicles have i seen with painted (aluminium) radiators,oil,water or air?

My personal opinion is that radiators were originally painted black because they were made from copper, and copper goes ugly very fast when exposed to moisture and air. It was probably also for looks, as you get that "empty" look when you can't see the radiator/intercooler. Lately I can't remember when last I saw any new car with a raiator/intercooler that's been painted black.

Think about aluminium foil that you use when cooking, it's got a shiny side, and a matt finiish side, depending on what you are cooking, mostly you will use the matt side towards the food, so that the direct heat from the heat source is reflected away by the shiny side, and you don't get food that's burnt on the outside, but raw on the inside. So if even that slight difference in colour can make a difference, just think what black would do, it would attract more heat even just standing in the sun.

Keep it shiny, looks better anyway...

Shiney surfaces retain heat. Thats why your gran would try to keep her teapot shiney, to keep her tea from cooling down too fast.
Some of chryslers engines has wrinkle black painted rocker covers. I've always found that chrome rocker covers retain heat to the point that the valve guide seals will bake hard in only 6-9 months.