Paint color and heat radiation

[Guest Anonymous]

Now I've been doing a bit of thinking about the effects paint color would have on radiation heat loss for surfaces heated from within.

 

Now we all know that black surfaces absorb heat better while white/silver ones reflect heat better. This means that for something like an exhaust pipe/headers, you want the inside to be silver, so as to minimize heat loss from radiation, increasing power a bit and reducing surface temperatures. Now the question is, does the external color have any effect on heat radiation? Is it better to paint the engine block black or silver? I would wanna keep as much heat as I can inside, to reduce underhood temps, maybe make a couple more horses I would think black would be best as it absorbs heat... reducing its emission, but then why are a lot of radiators black? I'm very confused here! I would also like to paint the tranny , cuz that thing gets hot and I don't want it getting in the cockpit.

 

As always, I'd appreciate your feedback

[Guest Anonymous]

Black radiates heat better... That means black would be best for the radiator, whereas the exhaust piping should be painted aluminum or chrome. My headers are already Ceramic coated thankfully, so that should cut down a fair amount of heat. Any second opinions?

[DavyZ]

Omar,

 

What you are saying is in effect true, but you are talking about the "Nth degree" of something. In the real world, is 1 or 2 degrees of heat difference worth the work, not mention the sacrilege, of painting a Howe or a Griffin radiator black? I dunno, just a thought.

 

Davy

[BLKMGK]

Couple of things, paint acts as an insulator for one thing. While it might help radiate heat the amount of radiation it does, especially on a radiator, is going to be offset if not overcome by the insulating effect of the paint. So, why do non-aluminum radiators come painted? Because they corrode far more quickly without the protection of the paint. Aluminum "rusts" too but it's not as quick unless salt is involved. You can buy "fin cleaner" which is actually acid from an A/C suppoly shop. I've used it on my home A/C more than once to clean the coils in the furnace once upon a time....

 

As for the rest - yeah Nth degree probably applies. Supposdly heavy grease on a motor can make the engine run hotter but if it takes that much grease to do this, and I doubt it really makes much difference, then I don't think paint color is going to do anything I have known women to be induced into having gaskets changed with that line though. After all, they wouldn't want to be stranded becasue their car overheated due to not changing that gasket would they? I hate dealers...

[Guest Anonymous]

Yeah you're right about that Nth degree thing... I was suckered into buying new (rubber) valve cover gaskets for my Nissan 240SX when I took it off to polish it. Damn dealer relieved me of $30 I guess you live and learn

 

So I'll probably go ahead and paint the exhaust piping and tranny silver/chrome to cut down on heat rejection. Probably won't do much, but what the hell . Is there any kind of high temp paint with good insulating properties out there? Any suggestions?

[Brad-ManQ45]

In the absence of light, Black radiates heat better.

 

Your best bet in reducing underhood heat is to ceramic coat the exhaust manifold/headers (inside & out- downpipe(s) too).

 

Paint your block whatever you want - any heat kept in will be radiated from the radiator, the air going into the radiator will be blowing through the engine compartment - no gain to be had.

 

I personally like the lighter color engine and engine compartments - easier to see leaks and light up in case you have to work on them on the side of the road at night/in a shop.

 

JMHO.....

 

 

Brad