Does a black engine run hotter than say an aluminium lacquered engine, or does it just feel as though it's hotter, due to better radiated heat? Discuss.

I read a hotrod magazine that claimed a transmission ran 10 degrees cooler with the pan painted black..

Armen wrote on 09/11/16 at 14:09:14:

OMG terminology.
In general, lighter colors do a better job of reflecting all wavelengths of visible light.  Black does a better job of irradiating heat.

Having said that, a lot depends on the type of paint or coating, you can have one type of white paint that's better then another type black paint.  Do your research before selecting a paint or coating they can vary a lot.

I read an article in an airplane magazine published around '75 or so that dealt with this. The writers had the opinion that certain colors were better than others.

Interesting! The reason I posted this is pretty obvious. My engine was a mess, so I had it blasted and gave it a single brush coat of satin black heat resistance paint. It looks good to me and went on really well. But now when I'm riding, and especially at traffic lights etc, the heat coming off the engine is so bad I have to stick my leg out ( exhaust side ) to keep away from the engine. My initial thoughts were that the engine was running hot, but then thought it must be running cooler if that much heat is being radiated away. I hope I'm right.

Not to discount your 'feelings' but you might get a cheap I/R temperature gauge and compare several points on your engine against others.

This is  VERY interesting.

I Always held to the credo, (as verslagen1 said: In general, lighter colors do a better job of reflecting all wavelengths of visible light.  Black does a better job of irradiating heat.)

Then, Dave said: “ the wrong kind of paint can also make things hotter (even black) - if they are not good at transferring heat and are applied too thick.”  

Sooo with that in mind,  (Not Thinking M.C.’s),  Would a ’Thick’ Layer, of paint, provide a better, ‘holding’, of the heat?
What kind of paint.   (Need to be stable at 750-800 f)

Use, two, ‘cans’,   (Old Freon cans), cut off two, one a 1/4” smaller in dia that the other. Coat the outside of the smaller one, and the inside of the larger one, with, a ‘heat’ resistance, (2,000 f), ’goo’, (or stove.pipe packing), which is water biased,  For melting 50-70 lbs of old wheel weights, on a 175,000 BTU LP burner.    It Works, BUT, it takes at least 10 cycles,  of heat, to ‘Just’ about 300f, then the goo in-between, boils, and I have to cool down.   Want to make them, so they work. with out having to, wait, 6 months, for it to dry naturally,  or waste gas and time, to, speed up, the process. (it may be 1/4 - 1/2” thick at spots.)

I make a ‘pot’ up, (with, Frankenstein ’ bolts), then they disappear. Then later, someone tells me, “Oh They Borrowed it”,  and I never get it back.   Thinking, the, ‘wrong’ kind of paint, liberally applied, then a piece of, ‘(Heat resilience), rope, around the top, ‘may’ do a better job ?   And faster ?

When I had the Trailtech Vapor...I put the temperature sensor on the left rear head stud, just under the nut.

I would get about 240 degrees on cool days of 60 mph riding.  On really hot days where temps were over 90 degrees, the temperature would get up to 280......and on a couple of 95 degree days and 70 mph speeds it reached 300 degrees.