Polished Radiator top vs. Painted top

[theleisure]

Hi guys,

I have a spare radiator that has been polished at the top to expose the brass(?) underneath. What's the deal with that-- is it just for looks or is there a function in doing that? Just curious.

 

[Trevor Jessie]

Just for looks I would assume.

 

[Hairyone]

Keep it black, matt black for the best heat dispersal.
Polished brass should only been seen on ships bells, or horse brasses in British country pubs.

 

[mxp01]

I found a solid brass plate on mine indicating where it was manufactued.

I kept the plate visible and painted the rest of the radiator black.

Mike Pennell

 

[Hap Waldrop]

Color/piant/no paint has no bearing on it's abilty to cool, here's the Huffaker MGB custom radiator, same one it came with when it was built in 1978 it was always unpainted, manufactuers paint them to keep the brass from tarnishing on the shelf, nothing more, it more work poilishing one, I race this car for years, and kept the radiator polished. If it makes you happy, polish till your heart's content.

 

[Hairyone]

Sorry: Black is best
https://en.wikipedia.org/wiki/Thermal_radiation

 

[ChrisS]

You're all right. Black is best and it doesn't matter. The top of the radiator is not a major contributor to the overall heat transfer ability of the radiator. The predominant mode of heat transfer in an automotive radiator is convection through the finned core. This becomes forced convection when the car is in motion or a fan is used. The effect of a black coating on the top is minor compared to air moving through the core. If you like the way it looks keep it polished, if you want the best possible heat transfer put a thin coat of black paint on it.

Side Note:
I think this car has a vertical flow radiator in it which means the top (inside) is wetted. For later cars with a cross flow radiator the top is just there for mounting and would have an even smaller effect on the overall heat transfer capacity of teh radiator since it is not in direct contact with the engine coolant.

 

[Hap Waldrop]

Yep, if it was truely important, you'd see pro racing (from Nascar to F1) painting thier aluminum radiators black, and you don't. There alot smoke and mirrors out there in the marketplace, a guy yesterday ask me about thermal coatings for his combustion chambers in his cylinder head, I told him, what good with will it do, it will be covered up with catbon in 15 minutes of running Not the say the technology is flawed, just flawed for that application.

 

[nomad]

My radiator guy uses a special black paint and says you should'nt use anything else because it reduces cooling. He hardly puts any on the core. I agree with the above about the tank very little cooling done there so do as you please!
KA

 

[nomad]

Ya know, while we're on this subject, I was wondering if there is any difference between the down flow and the cross flow as to cooling ability. I've had people who seemed to know swear that the cross flow cooled better but if you measure the cores and put the radiators along side one another the down flow acually appears to have more core area. What do you think???
KA