Painting engine & g/box

[vanzen]

I'm with Duane.
Why paint the cases ?
The result can only be cosmetic
even as heat dissipation may or may not be affected.
Am I slowly evolving into a traditionalist ?
Well, no - but I am a staunch believer
in the honesty and integrity
of quality craftsmanship & materials.
BMW cast aluminum being a fine example.
I'd be thinking of either soda blasting the cases
or being comfortable
with an appreciation of the patina
as exemplifying a well deserved heritage.

[Duane Ausherman]

From the /5 and later, the BMWs had very good cooling. Still, I wouldn't mess with it. A smooth surface in the wind has something called a boundary layer. There are a few types of boundary layers.

Not being an engineer, I don't know how this smooth surface would allow cooling by convection. I prefer the original rough surface for maximum cooling, but I could be way wrong.

For example, fly a plane with a dusty wing and when it lands, the dust is still there, just as before. I would be more concerned with heat transfer than decreasing the drag. This affect could be so small as to not exist.

I am sure (hope) that some engineer jumps in to straighten me out.

[ME 109]

I am sure (hope) that some engineer jumps in to straighten me out.

Wot, no more Diane?
Any engineers out there?
I'll ask over at ADV.

[Garnet]

I am sure (hope) that some engineer jumps in to straighten me out.

Wot, no more Diane?
Any engineers out there?
I'll ask over at ADV.

No need Jeff, I'll ask the engineer that I know............ as soon as he has the steam up.

[Jean]

The rough surface will dissipate heat better.

[Toga]

Thanks for your replies.
It is interesting to hear the feedback, which begs to question...
If a rough suface does in fact dissipate heat faster than a smooth surface, why is the diff case smoother than the 'dimpled' engine block & gearbox case considerably smoother still?
I had no interest in going as far as he did in that pic, it was only used as an example.
I was personaly only interested in doing the diff black..
Umm i meant bright red to go with the red snowflakes
Oww... sorry, for the purist's I meant clean alloy as OEM, re-blackened black & a duplicate candy apple red spray job * I note NO pinstripping was OEM on this colour... *phew, that was going stretch my minimal talents
Will have to see what I can come up with

[ME 109]

The rough surface will dissipate heat better.

'Cause there is more surface area.

Garnet, that's an ingineer. Not a lot of difference between the brakes on a steam loco and a diesel loco.
There's an engine brake and a train brake. They are the two horizontal 3/4 dia. by 6" long handles. Not sure what the lever above the drivers right hand is.

[Jean]

really simple additional explanation:
The rough surface causes turbulence which means more of the airstream contacts the hot surface.
Duane's comment about "boundary layer" is part of this...a boundary layer acts sort of as insulation.
Sometimes it's useful, sometimes not; boundary layer vs. turbulence is also dependent on velodity.

[Garnet]

Soooo to really confuse the cooling issue........ BMW began painting or coating engine and tranny and drive cases in the 80"s.

[Jean]

Mine's coated with oil.
Seriously, maybe they figured you wouldn't go fast enough to notice the difference in cooling.
OR maybe they didn't care about THAT.
Fancy coating sells.