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[Tony - www.1700cc.co.uk]

Yo there ... to old friends and appologies for not logging on for so long! Guess I have been riding a lot ... European HOG Rally in Ireland and all.

Anway on to my question ...

Is it silver or black engines that run cooler.

Regards
Tony

[SPIDERMAN]

The silver engines are a sand cast finish with no coating. The black engines have black heat paint on them. Anytime you add any coating to a heat producing surface you trap some of the heat in. That's a basic rule of physics. So my answer is the silver motors run cooler

[Tony - www.1700cc.co.uk]

Hey Spidey,

That must me why they make Screamin Eagle bikes silver then hey?

Tony

[UK Dave]

The silver engines are a sand cast finish with no coating. The black engines have black heat paint on them. Anytime you add any coating to a heat producing surface you trap some of the heat in. That's a basic rule of physics. So my answer is the silver motors run cooler

Gotta disagree there Brian, my silver engine ('05 SEEG) is powdercoated

Granted, some of the silver finish engines (softail standard?) are just natural aluminium - no coatings

With that in mind the black coated engines will run cooler that the silver coated ones since a black surface will radiate more heat than a silver one

This is why we forever burn ourselves on the (chrome) pipes - we don't feel the radiated heat until it's too late - Ouch!!

I also think the radiant heat loss from the black coating is going to overcome the insulating effect of the coating itself.

Cheers

Dave

[grc]

Actually, engine cooling is affected much more by convection than radiation, and color doesn't have any affect on convection.  Convection is more dependent on surface area and air flow. When dealing with radiation, black is both the best absorber and emitter of radiant heat.

Jerry

[Twolanerider]

The silver engines are a sand cast finish with no coating. The black engines have black heat paint on them. Anytime you add any coating to a heat producing surface you trap some of the heat in. That's a basic rule of physics. So my answer is the silver motors run cooler

Brian, the silver motors have a silver powercoat.  Wait til it chips; you can see it then sure as hell   .

[Twolanerider]

Convection is more dependent on surface area

That's why D00d needs to get his cyclinder and heads diamond cut!

[fatboyse2]

Actually, engine cooling is affected much more by convection than radiation, and color doesn't have any affect on convection.

[Fired00d]

That's why D00d needs to get his cyclinder and heads diamond cut!

I would if I had an extra set laying around like my friends do.

 [smiley=pumpkin.gif]
Ride Safe,
Fired00d
 [smiley=fireman.gif]

[SPIDERMAN]

Well,  maybe your later model CVO's are powder coated, but Elvis doesn't appear to me to be anything other than plain old sand cast. I got oil on the inner primary before I changed it to chrome and it didn't come off. Stained it but good. And the inner primary matched the rest of the motor. Silver powder coat  harumph I say.

While I agree with surface area theory,  given that all H-D motors  have basically the same surface area, I stand by my belief that a sand cast silver colored motored with no coating will run cooler than one with black powder coating.  

[Twolanerider]

I would if I had an extra set laying around like my friends do.

 [smiley=pumpkin.gif]
Ride Safe,
Fired00d
 [smiley=fireman.gif]

Eventually there will be a spare set resting on a shelf below a work bench, lonely all by themselves, in the garage of someone you know.  [size=8]THEN WHAT WILL BE YOUR EXCUSE! [/size]  

[grc]

I beg to disagree here.

[Fired00d]

Eventually there will be a spare set resting on a shelf below a work bench, lonely all by themselves, in the garage of someone you know.  [size=8]THEN WHAT WILL BE YOUR EXCUSE! [/size]  

Oh so tempting that is, however if I don't refrain from major expenditures on my scooter I will be needing to move in your garage. [smiley=nervous.gif] At least that is the word I'm getting from "management".

 [smiley=pumpkin.gif]
Ride Safe,
Fired00d
 [smiley=fireman.gif]

[Fired00d]

Fatboy,

Now that I think about it, while your chrome engine may not run the coolest, it will probably be the fastest due to lower wind resistance.

[ridefar]

Just compared oil temps at the digital dipsticks on my 2004 SEEG and my bud's '07 Ultra(standard model): same load,route. His is new presumably with mineral based oil, I'm using Mobil 1 V-twin. His oil temp was 33degrees hotter! We always compared temps on his recently departed '03 Ultra and he ran consistenly only 4 or 5 degrees hotter. One of the things that he is complaining about on the new bike(and there are many!) is the heat coming off the motor, which is black.