Does painting engine fins reduce cooling.

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OK....digging back into my heat transfer class from 1980...

There are three mechanisms for heat transfer....conduction, convection and thermal radiation.
 

Fun fact (and fun thought exercise): convection currents do not work in zero gravity.

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wrote:

OK....digging back into my heat transfer class from 1980...

There are three mechanisms for heat transfer....conduction, convection and thermal radiation.


 

Fun fact (and fun thought exercise): convection currents do not work in zero gravity.

Close but not totally correct.  Convection works on the space station.  I think you meant that it doesn't work in the absence of air (in deep space) and that would be true.  This is why the only way heat can escape the earth is via thermal radiation.

All objects emit thermal radiation towards cooler objects.  The amount emitted depends on the temperature difference between the two.  Light is just a specific part of the emission spectrum that includes ultra violet and infra red.  The only difference between these three is their energy level.  If you heat something high enough it will emit light...which is why steel begins to glow when it's really hot.  Under normal circumstances it only emits infra red energy.

 

Question for you all, maybe to re-rail this thread but does a polished block transfer heat better or worse? As the size of the pores in the metal have been reduced, just curious because mine has begun to oxidize and doesn’t look all that appealing so just seeing what my options are. 

Mine was doing the same thing. Back in the day cleaning it up wasn't an option so I painted it black. I like the look anyway. It does seem to run a little hotter and my oil cooler seems to deal with that. It is a matter of taste more than utility. The Z1A/B's weren't painted as were the KZ900/1000's. They did have a clear coating on them and that's what made them discolor so badly. I never liked the look of the silver painted engines (cheesy) and had the same questions abut heat dissipation. I suspect black, silver or clear dissipate heat at about the same rate. 
Steve

Could a ceramic coating be an option.    Can You Ceramic Coat Exhaust, Engine, and Turbo Parts? (avalonking.com)

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wrote:

Fun fact (and fun thought exercise): convection currents do not work in zero gravity.

Close but not totally correct.  Convection works on the space station.  I think you meant that it doesn't work in the absence of air (in deep space) and that would be true.  This is why the only way heat can escape the earth is via thermal radiation.
 

I was thinking of convection currents where warm air rises because it is less dense than cooler air, e.g. weather type currents.

Would the space station be described as having microgravity rather than zero gravity? I could see warm air rising/cool air falling in that sort of environment since little force would be required to move the air.

The way I understand it (which could easily be wrong - this isn't my area) is that if you were way the heck out in the middle of space and you had a silo-type living enclosure, you could have a heater in the bottom of it and the warm air wouldn't rise because there would be no gravity to pull the cold air down to displace the warm air.

There wouldn't really be an up or down out there, either, but we'll ignore that for now.

The space station is being affected by gravity, and plenty of it.  But because it is in free-fall, it and its contents experience weightlessness.  Its forward speed is so high that the curvature of the Earth is such that the Earth's surface "falls away" at the same rate, so it doesn't actually get closer to the Earth. If it stopped its forward motion, gravity would immediately begin to pull it toward earth. 

So it sort of breaks down to a semantics question, or a philosophical physics question... if you are in freefall, are you experiencing gravity?  Or... in other words, if you don't *feel* gravity, are you actually experiencing gravity. 

 

The best analogy I can think of is that painting an engine is like throwing an extra blanket on your bed when you feel cold at night.  It may be a very thin blanket but it has a similar effect, probably not significant in the larger scheme of things.

Steve, this is the first I've heard that '74 and '75 engines had a coating.  I bought one new back in '75 and I don't remember a coating on the engine.  I remember a coating on the carb tops though.

I think it's like the coating on the fork lowers. Very thin but started yellowing in the desert heat and sun.
Steve

Kal Gard makes an engine coating called Gun Kote. It came about from some military or space program way back in the '60's. This coating when applied to motorcycle motors helps greatly with heat dissipation. Yoshimura has used this coating from the very early days of their Superbike program. Its a very durable coating too!!! NOTHING takes this coating off when applied correctly. The only way to remove it is to glass bead or sandblast it!!! Most racebikes in the '70's and '80's had this coating applied to their motors. Suzuki has used this very same coating on all their oil cooled GSXR and Kanatuna motors since those bikes first came out in the showroom. I believe they still apply this coating to their GSXR model bikes. This is the only engine coating I know of that actually helps in the dissipation of engine heat.

  Suzuki GSXR750 motor with the Gun Kote coating.
 

Kz1000 motor with the Gun Kote coating.
 

I had always heard that Pop Yosh believed in black engines running cooler

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Kal Gard makes an engine coating called Gun Kote. It came about from some military or space program way back in the '60's. This coating when applied to motorcycle motors helps greatly with heat dissipation. Yoshimura has used this coating from the very early days of their Superbike program. Its a very durable coating too!!! NOTHING takes this coating off when applied correctly. The only way to remove it is to glass bead or sandblast it!!! Most racebikes in the '70's and '80's had this coating applied to their motors. Suzuki has used this very same coating on all their oil cooled GSXR and Kanatuna motors since those bikes first came out in the showroom. I believe they still apply this coating to their GSXR model bikes. This is the only engine coating I know of that actually helps in the dissipation of engine heat.

  Suzuki GSXR750 motor with the Gun Kote coating.
 

Kz1000 motor with the Gun Kote coating.
 

Yep, KG industries 2400 series paint is the one...

shop.kgcoatings.com/kg/product/2401df/