Jason Moyle Racing

I like this subject, raced 2stroke bikes for many years and heat management was exerything.

Black rads, inside snd outside, are better to radiate heat. But the design is probably more critical, especially the fin vortices, fin count, and effective ducting. And need to keep fins in good condition with no crap in there.

Re inlet manifold, as this is bolted to a big heat source, the head, conduction heating is most significant. I have a phenolic insulator gasket between the head and my tbs to try and reduce heating of inlet tract. I suppose you could polish the outside to try and reflect engine bay heat. For a boosted engine, maybe black inside and out would be an idea to reduce intake air heat.

Cheers Rob , it was your topic on the waterpumps reminded me of this .

Is your exhaust coated all the way to the head? I'd heard that's a major no-no! Aparently heat soak back into the head has caused everything from warpage to valve seats falling loose! Haven't seen it myself , just what I've read on it , most;y from Guy croft , ex Hart Racing engineer.

http://www.guy-croft.com/viewtopic.php?f=13&t=759

Nice topic....

After a lot of studies on another contract involving heat sinks on cpus(fanless) the general consensus and testing proved that bare/silver was the best. (Cpu heat sinks is what you should be reading about in this case as maximum cooling is needed and always in the smallest possible space(laptops, pads, etc)

For the simple reason that no easy to do/affordable black coating was possible  without slowing heat transfer at the metal/black coating interface. Nearly all coatings slowed the heat transfer bar one or two which were uber expensive and which I cant remember the names of(Ill find out - not off the shelf gear)
The two that were expensive were loaded with copper powder and a silver loaded conductive paint. The black colour came from graphite talc - also in the mix.
After many many thousands of dollars, they found/went with a light bead blasted alloy finish.

For anyone wondering if the above was aimed at mass production - initially it was not. The testing was done with just 5 heat sinks.

The bead blasting increased the surface area of the extruded profiles something like 13%, which helped with the cooling too, as well as doing away with the mirror(ish) surface.
Laser blasting further increased the surface area to a finer pit size and also changed the colour to black. On comparing both lasered samples black - and desmutted(silver colour again) the silver one did better since the pits were deeper once the smut was evacuated.

Another thing to look at is F1 radiators - cross-sectional area vs cooling vs drag is paramount with these and Ive yet to see a black one I think.
Or the skin of the sr71 - this has a coating both to disguise in the night sky, protect from radar, and emit heat better. The coating is hard get info on, but it has a very fine pitted surface(more area) and is applied onto an already corrugated surface(for expansion) This coating was super dooper uber and nobody really knows anything about it. The skin gets further cooled by pumping the fuel around under it.

As mentioned by Rob - design and layout is more important than anything.

Beat blasted copper or beryllium copper would be better than aluminum but cost gets crazy. Or diamonds - the best conductors!

Whatever you do dont black anodize - the anodize coating is and acts as a ceramic type layer and hurts performance a good bit.

For the manifold, get some gold film and stick it to anywhere hot air from the rad is likely to blow - an insulating spacer helps too, but some heads are thermally sim'd @ time of design with the intake acting as a soak. And Im told can warp if you space off the manifold. I find this hard to believe though and certainly so if it comes as standard with a glass-filled nylon manifold - obviously!

Carbon manifold - gold film(its not that dear)
Alloy manifold - polish/gold film
Head - pitted cast surface will give highest cooling area
Rad - hard do a lot with these, but extrude hone to rough up internally, externally, light bead blast.

Personally, I wouldnt worry about any parts bar maybe keeping the intake cool.
If its running mega hot, fit a bigger rad, or pump the water around faster(or slower - thats a tricky one to figure) or duct in and out better.(wheel arches are normally low pressure and a good exit)

Lots of boring info there, if ya want thermo calcs thick and heavy shout,

Brian,

Invaluable information Brian. I was talking to Jason about colours and he suggested i dont paint my manifold black for heat management reasons, I was going to paint my entire manifold black for aesthetics.   I have painted the lower halve black already, on the dyno the black portion was considerably hotter than the bare alu part. (Other factors do come into this also, one being the part is touching the head etc..).

Anyway, it was enough of a difference for me to change tack, the plenum will be polished to reflect the heat and the runners are going to be painted silver (aesthetics also play a part for me, unpainted the runners look a little rough and I'm not going to spend time polishing those, would be a very time consuming process!).

thread revival! Any more thoughts?

The way I read Brian's post, any coating is bad news if you're trying to radiate the heat out  (including paint... paint weighs a bit anyway) but if you're trying to keep heat out rather than let it out... coatings are good?

So... on a 16v lump or 8v X-flow bottom half of the inlet is next to the cylinder head  heat source... so I guess light bead blasting and a heat shield to keep the radiated heat off... top half should be about keeping heat out... ceramic coat and let that lovely cold air rush in? Again, if it's near the radiator does a heat shield provide better results than coating - my 'logic' is that by the time the heat gets to the coating it's already 'in contact' with the component you're trying to keep cool. Coating + heat shield could be the best option...
 
Another option might be to get heat out of the front of the bonnet via a vent at the front, in the low pressure area behind the leading edge of the bonnet, and just behind the slam panel/radiator? Depends on the space constraints with the particular car and engine though.