poss

iTrader: (5)

http://www.autospeed.com/A_0188/page1.html


The last sentece of the 2nd paragraph:
"Intercoolers should also be painted matt black for maximum heat dissipation."

This makes no sense to me. it seems that the paint would act as an insulator. Do they know what they are talking about?
anyone have any ideas?

user 84205

I think they are just promoting bullshit...... Why have a black intercooler if you have polished piping? doesnt make sence to me....

futurerexowner

Any black finish would absorb more heat than a lighter color, thats 8th grade science knowledge... It would negate the idea of a cooling device. In my opinion.

user 84205

so whats the point of them saying you need a black intercooler, but get these nice shinny intercooler pipes??
I dont doubt the cooler thing, but sliver is not white..

Nathan Kwok

They are possibly correct. Jumping from 8th grade to college level knowledge, black objects are better thermal conductors than white or reflective objects. Don't confuse thermal conductivity with specific heat, conductivity is entirely a measure of a material's ability to TRANSFER HEAT. The reason a black object feels "hotter" in the sun than a white object is not because it holds more heat or is at a higher temperature (a common myth), rather it is because it is better at transferring that energy into your skin for you to feel. Its the same reason a frozen rag doesn't feel as cold as a frozen ice cube, they're both coming out of the same freezer don't they? Now, I can't prove that the insulating effect of paint isn't overcome by the conductive effect of the color change, but there is a solid physical basis for such a claim. Why aren't all intercoolers painted black? Probably not worth it, and more importantly, it doesn't look as good. Also, FWIW, the same principle applies to the piping as well, but only on the "hot side" of the piping. There are parts of the engine you want to insulate and parts you want to transfer. The "cold" side is probably colder than the surrounding engine bay, so you insulate that part, but the "hot" side is much hotter, so you want that to be disappated. In any case, there isn't much heat transfer going on in the piping, and you may not want heat radiating off in the wrong places, but I'm straying...

user 84205

So why are we even talking about this... Some people should keep the insults down.. No reason to be a ***.
Let just help give our opinion and go on our marry way!

Nathan Kwok

I don't mean to be insulting but I'm trying to dispell a really common myth that people learn in grade school and never let go of, the whole "black is hotter white is cooler" deal. In this case its pretty trivial, I agree, but this is a pretty important concept in a hot running car like the rx-7. For example, lets say you test two radiators: one feels really hot after a hard run and the other feels not so hot. Which is the better radiator, the cooler feeling one or the hotter feeling one? Answer: the hotter feeling one. Why? Because if it feels hot on your hand then that means it feels hot to the surrounding air as well. If the air around it is feeling the heat, then that means its giving it off effectively. Intercoolers work the same way. Heat exchangers are supposed to give off heat, they don't generate it, so if they feel hot, thats a good thing. So if you're thinking, well a black intercooler would be hotter than a silver one, thats the idea. Just my two cents.

rotorbrain

im not very positive on the balck paint thing either. i do know that old hot rods had balck engine bays . . . not motors. possibly to keep the heat off the motor? but if i remember correctly lighter surfaces reflect "light" and darker surfaces absorb "light". it is the absorbtion of light that might make the black surface feel hotter than the lighter surface. just like your black car. it absorbs light and the light energy is transferred to heat energy. it probably doesnt make a bit of difference what color everything is. i would say heat is affected by material used and not so much by color used. oh yeah, about the hot-rod thing. . . a lot of those guys ran around w/o hoods. . . maybe they didnt want the suns rays messing with their engine.

rotorbrain

heat dissipation is also affected by design too. . . of course. hehe

maxcooper

There is special radiator paint that goes on thin (and may have other properties) so that it doesn't get in the way of the heat transfer. Oil coolers are often painted black. It seems like a reasonable thing to do if you want a black intercooler, but I would be surprised if it made a big difference (one way or the other) overall. Don't use regular paint.

One reason to go black is to make it look like an OEM part for the smog *****.

-Max

martini

well, I suppose the IC could be annodized black, and not painted.

neo_omega

But IC is not a smog equ. isn't it?

FD3S LIGHTNING

I'm leaning towards Nathan's point of view. Bro, you really know your $hit

neo_omega

But have you think about why is the lighter color one cooler? It's coolder maybe it retains less heat.

I could be wrong. Thermal Dynamic is not my strong subject

Nathan Kwok

Neo,
Heat retention is mostly a function of mass, so applying something thin to the surface isn't going to change the amount of heat the object can retain, it can only affect the way it transfers it, because heat transfer occurs on the surface. Take exhaust wrap for example, you think that thin piece of cloth actually absorbs any heat? Nope. All it does is keeps it contained inside the downpipe so it'll head out the tailpipe instead of into the engine bay where it'll do harm. Think of black paint as a "reverse exhaust wrap", instead of insulating, it conducts. It absorbs heat faster, yes, but it also gives it off faster too. However i'd listen to max, i doubt slapping any kind of paint on there is going to help. In theory it may, but an IC fan of any color is probably a lot more helpful.

Tim McCreary

Nathan is correct. If you take two identical size containers of the same metal, one painted black and one painted white, fill both with the same temp hot water and measure the temperature drop. The black one will radiate the heat away quicker.

Now, If you coat the intercooler fins with black paint, there would be the advantage of increased release of radiant energy. At the same time, the paint may insulate the thermal transfer from the metal to the air. Your best bet is to have the aluminum annodized black to have the best of all worlds.

The advantage to shiny pipes would be to keep the radiant heat transfer to a minimum. In other words, if the cool side of the pipes are shiny, they are less likely to absorb the radiant heat from surrounding heat sources.

Tim

Montego

iTrader: (1)

I completely agree with you. BTW I didn't think you were being insulting just some people are a bit sensitive I guess.

Want2race

i agree,... if the heat is on the outside of the radiator.. Thats a good thing. The inside should be cooler as a result... Total heat=Absorbed heat +released heat!

fdracer

For the people who don't understand why black would be better, look at the pipes behind your refrigerator, they're black cause they conduct heat better. That means they soak up the heat from your refrigerator thus making it cooler.

7-sins

lets just call it a day and coat it in jet hot

poss

iTrader: (5)

thanks guys for all the info. i was thinking it was either a little odd, or maybe something that i should do to maximize cooling.

rxrotary2_7

i agree with kwok

mmaragos

Aw...come on, no one else is going to examine the minutiae here?

I haven't seen BS flow this freely for a while. I worked for Modine. The Cu-Br rads were painted for looks only and some corrosion protection, nothing more. No significant heat transfer increase (tested with and without paint). The Al rads were not painted (majority), because they are aesthetically pleasing and have better corrosion resistance. (some Al rads where painted to better hide them behind grills)

Additionally, the paint will add some weight to your heat exchanger.

futurerexowner

I agree that black tranfers heat better and all that but all I was saying is that it will also absorb heat from the engine compartment as well as other places(light , air, etc) that a lighter color would not absorb AS much of. And also I am not positive but if an IC is made of aluminum or not, but, that is already a great heat sink... it is used in all kinds of these types of applications, painting it black will dissipate heat but will also insulate(maybe not so much with previously mentioned thinner paint) and it will still absorb more heat.

mmaragos

STOP THE INSANITY!

It isn't going to make a measureable difference. If you like the look and want it to be heavier, have it painted.

I don't believe that you will find any Cu-Br radiators or ICs for the FD, whatever you are looking at it is aluminum.

EDIT:
I just recalled that we did get a decrease in efficiency when the paint was gooped on the fins. But get a good paint job and you shouldn't have to worry.