I would like to hear some thoughts on engine painting. When I was younger, I use to follow a Chevrolet engine builder by the name of Smokey Yunick.
When I built an engine, I did as many of the modifications, he suggested and had great results. The two things I would like your thoughts on are as follows.
1 of these was painting the inside of the engine with a marine red primer, that is everything that was not a moving part or the inside of the cylinders, of course. This was primarily for quick oil return to the pan.
Another was painting the exterior, including intake, runners and all. Black was the color of choice, because of its ability to radiate heat, better than any other color. He claimed that the engine will run 10 degrees(F) cooler.
Now I know Black absorbs radiation, i.e. sunlight, more than any other color, but inside the bay, not too much sunlight hits it.
There used to be a column in the newspaper, by LM Boyd, and he was a fact checker, like Snopes. He confirmed this about black, and explained this was the reason vehicle radiators were painted black. I just wonder why they are unpainted in modern vehicles, and if painting them would help or hurt. Could be the paint acts as an insulator, and therefore better to leave alone?

 

interesting. that oil return surely makes perfect sense (as long as the paint doesn't flake and clog)
on the engine, I thought the cast iron was better suited for painting and aluminum radiated better in the raw.....but I dunno. I have seen a lot of black radiators.

 

I was told by my machinist(old school guy) not to paint the aluminum block as the bare finish helps heat escape.

 

he is correct painted aluminum will run hotter, ask any Harley owner.
there was a time when Glyptal was used to paint the inside of blocks for better oil return,
but problems arose when it was found that it does not stick to vertical surfaces to well.

as far as the black color, i find it hard to believe if a light source is not involved. So if i paint the inside of my house dark colors I wont have to spend $4k a year heating it.

 

That could very well be. All the engines i have built have been cast iron, and painted them all. I am going to do some more research on the aluminum castings.
Dusty1, I never had a problem with paint flaking, but then preparation of block was key. Back in the day, they were hot vat cleaned, and scrubbed them down demurred , chamfered the oil return holes, blew out and let thoroughly dry.

 

DROWSSAP, I have no experience with Glyptal, although in searching engine paint, that is all that comes up. I have been trying to find out the exact paint i used to use.

 

I did a search"does bare aluminum radiate heat better than painted black?"
After searching on some physics sites, the aluminum painted black radiates heat a great deal more than left unpainted. Although, the more you polish aluminum, the less it radiates heat.
very interesting reading.

 

that is interesting. i assume that the tighter surface pore created by polishing, acts as an insulator barrier while the textured casting acts as mini fins...

 

give the man a cigar

 

Gotta go wax my car...makes me get better MPGs!