Effectiveness of black ceramic coating
 

A question came up on FFR forum a few days ago asking if black ceramic header coating was any less effective than silver. I shot my black headers yesterday with the engine on a fast idle and got about 740 +/- 20 degress or so. I'm thinking not as effective. Anyone checked their silver coated headers

In general black is a better color for radiating heat away from the object while white or shiny will tend to dissipate it less readily.
DonC

Are you trying to measure pipe temps or radiated temps? What are you comparing it too?

If you really want something that is going to stand up and be next to impossible to remove without a grinder I suggest you look at Swain Tech Coatings. That is some awesome shtuff!

I'm shooting pipe temperature with an IR gun. Not sure how closely that will cross reference to radiated temps although I anticipate the higher the pipe temp the more radiated heat. Underhood radiated heat is what most of us are concerned about.

Dan, it's not the colour that makes a difference under the hood, it's the material and the thickness. If your black ceramic coating is the same material and same thickness as silver ceramic, then the amount of radiated heat from your pipes should be similar.
Colour comes into it if there's another heat source (like the sun). A black coating will soak it up but a light colour will reflect.
Cheers,
Glen

Also whether they were coated on the inside also, will help contain the heat.

Paul...

I used CeraKote on my cast iron exhaust headers and my entire 304 stainless exhaust system minus the intermediate stainless section which we had electro polished. We heated the manifolds to 1200 degrees without discoloration. I also coated my intake manifold to match the cast iron headers. This is the material they use to coat weapons including rifle barrels, a very durable product. Time will tell.

Yes, they are coated inside and out. I agree the material thickness probably makes a difference. I have undercar exhaust and after shutting off the motor I shot the collector/head pipe and then the muffler. The baffled mufflers were ceramic coated also but may not be as effectively coated inside. The muffler was nearly twice as hot - great little heat sink.

So no one thinks the coating color matters on radiated heat?

I think with a ir gun, the readings are not accurate with different types of surfaces. I remember seeing a chart to work out the differences. You really need to put a temp probe onto the pipe itself.
JD

I think it would be hard to tell the difference if any without knowing the different components in the colored coatings, or without doing a same car comparison with different colored components. Maybe CCP coatings will offer up some insight. My headers are coated inside and out with a special matte grey higher heat coating and the side pipes are coated with the shiny silver inside and out. Will take some readings tomorrow.

Paul...

[ame]https://www.youtube.com/watch?v=P1Z_Zv2ue-w[/ame]

Here is a link to a you tube video explaining some attributes of CeraKote. I had my parts professionally coated. The CeraKote finish is thinner than Jet coating and doesn't have that orange peel look that you get with some coatings. I'm going to use this coating on a flathead Ford engine project (heads, intake and other engine parts).

I had my aluminum inner fenders anodized while they were out during the engine installation in CSX8967. I think I may CeraKote the inner fender wells on the Kirkham Cammer project.

If your a gun guy you will be interested in the video.

[ame]https://www.youtube.com/watch?v=P1Z_Zv2ue-w[/ame]

Here is a link to a you tube video explaining some attributes of CeraKote. I had my parts professionally coated. The CeraKote finish is thinner than Jet coating and doesn't have that orange peel look that you get with some coatings. I'm going to use this coating on a flathead Ford engine project (heads, intake and other engine parts).

I had my aluminum inner fenders anodized while they were out during the engine installation in CSX8967. I think I may CeraKote the inner fender wells on the Kirkham Cammer project.

If your a gun guy you will be interested in the video.

Dan,
Checked my headers and side pipes today when I got back from a drive, water and oil temps all up to normal. With eng. at idle, Headers 450f, side pipes where they exit the body 220f, side pipes-mufflers 85f, turnout exits 75f.

Paul...

Wow - that's a lot cooler than the 700 (+) deg I read on my black headers. :eek: I guess that tells us something.

Paul - after thinking about this - are you sure of your readings? 85 F for your side pipe mufflers is hardly even warm. Not going to get any snake bite from that. Even 220 just above the collector seems really cool.:confused:

I googled around and found some interesting facts, theories, stories on the subject of ceramic color for exhaust headers.

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One post:

99% of IR guns used are calibrated for use on a flat black surface. Colors have a different emissivity value. The example I use during training is the heating of a bearing ring which is shiny ground metal. The automatic shutdown thermocouple limits the temperature rise to a user set 225*F. Shoot the ring with an IR gun and the temperature reading will be 1/2 or less than actual. Spray the ring with some flat black paint and all is well.

So, what does this mean for the individual and for the group? For the individual it means that you can compare cylinder-to-cylinder temperatures if the gun has the temperature range. However, the temperature may not be accurate unless the color surface matches the IR gun calibration or the gun has an emissivity adjustment. For the group, it means that trying to compare different header coatings using different guns will yield results that will likely not be usable.

Another post:

Without getting too technical at first, Carl is on the right track here. Color isn't the only driving force behind emissivity though. You can take a flat paint of varying shades and their emissivities may be identical. IR is oblivious to color.

The basic equation for determining emittance is:

E + R + T = 1

Where:

E is Emissivity (IR emitted)
R = reflectivity (IR reflected)
T = Transmissivity (IR Energy passing through the medium)

If the part being measured is opaque, then transmissivity is zero. For most metals we can therefore rule this out.

The flat black surface Carl refers that these guns are calibrated to is actually referred to as a blackbody. There is no such thing as a natural blackbody. A blackbody is a perfect emitter. ZERO reflectivity. A good surface/contact thermocouple is great way to assist in determining how accurate your readings are. There are various techniques for calibrating these devices, but since we can actually see and access the surface to be measrued, a good surface TC can help you in determining how accurate you are. If you have an IR gun that allows you to adjust the emissivity, you can then back your way into an accurate reading with your IR gun based on the surface TC reading. And now you can take readings off other locations with the gun....

If this isn't coherent, well, thats because it is 3 AM... I carry a Level II certification through ASNT for Infrared inspection. Feel free to ask me anything you would like to know as far as IR is concerned.

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So - I guess from the above it may be hard to compare IR temp reading on headers of different color ceramic coating - and my flat black ceramic coating is probably going to naturally read higher just due to it being closest to a "perfect emitter". Interesting.:rolleyes: