thermal coatings


Staff member
There are 2 basic types of piston crown coatings,
first is the older style that is either light grey a silver color, or in some cases black.
those coatings tended to break down at just over 1000F
This coating is very similar to what is used to prevent rust on coated headers
The newer heat barrier coatings are frequently gold in color; they can handle higher temperatures in the 1600F or slightly more range, such as nitrous or turbo engines tend to have.
the coatings tend to block the transfer of much of the combustion chamber heat to the lower piston reducing the tendency to get into detonation on the sharper edges of valve pockets, or edges of pistons The coatings tend to keep the to heat locked into the combustion chamber where it promotes a more rapid flame front, reducing the need for longer ignition advance curves.that reduction in heat tends to reduce the reduction in strength that high engine temperatures can have on aluminum alloys, that tends to increase piston life and durability.
you can run a little tighter than before since your pistons will stay cooler and not expand as much, that means less rocking when cold and a tighter bore fit for better oil control and better ring seal.
most shops carefully tape the ring grooves then chemically etch the piston decks to gain a better mechanical grip to the pistons upper surface for the thermal barrier coating, some shops use a steel shot process, to gain a micro rough surface finish before the coating applied.
while the price to coat a piston can easily come to 50% of the cost of the less expensive pistons if it prevents a catastrophic engine failure its well worth the expense

links with more detailed info,

viewtopic.php?f=53&t=4516 ... index.html ... tions.html

engine Coatings - Coated Paths to Power
Race Engine Coatings
These lifters feature a special...

Race Engine Coatings
These lifters feature a special DLC coating. DLC stands for diamond like carbon which creates a super low friction surface that is both harder and more scratch resistant than conventional surfaces. Courtesy of Comp Cams

Dry Film Lubricants
- These are the friction reducers, sometimes called "solid film lubricants." Far surpassing the benefits of bygone molybdenum disulfide suspended in lubrication oil, dry film lubricants are highly effective in reducing friction, heat, and surface galling. Since the lubricity portions of these materials are what provide the benefits, it's important that a good binder be utilized to keep the lubricants in place. Aside from gains made in friction reduction (particularly friction horsepower), the companion benefit is in heat reduction at the working surfaces.

Chemical or Corrosion Resistant Coatings
- Materials in this category serve two fundamental purposes; (1) extended product durability or use life and (2) maintenance of appearance. We'll touch on specific areas where these coatings are of value a bit later.

In the same order they were previously presented, let's examine some specific uses for the coatings categories discussed.

Thermal Barriers - Here, the obvious areas are the combustion space and exhaust gas path. As mentioned earlier, my first and disappointing experience coating piston crowns showed power gains but damaged parts. Fortunately, with today's coatings technology, such problems are passe. So as you might expect, coating piston tops (and bottoms), combustion chambers (in certain applications), the faces of intake and exhaust valves, and complete header systems with these type of heat-retention coatings can be of particular benefit. Keep in mind that power equates with heat in a controlled environment. Therefore, combustion heat lost to cooling systems, combustion surfaces (all of them), and along the exhaust path can combine to reduce net power. Your best bet is to either consult with your choice of parts manufacturer already providing coated parts, or identify a good supplier of coatings materials if you elect to do the job yourself. And don't rule out the latter. Given the current state of some "kits" that are user-friendly to the engine builder, you can also get good results by these methods.
Race Engine Coatings
This camshaft has a new pro...

Race Engine Coatings
This camshaft has a new pro plasma nitriding process that enhances the performance all around. Courtesy of Comp Cams

Thermal Dispersants - Wherever you find that heat buildup is a concern, these are the materials to consider. Such components as brake parts, oil pans, radiators and intake manifolds all can fall into the need for rapid heat transfer or control. In areas where continual and/or repeated temperature spikes occur and you need to move heat more quickly away from these locations, consider these coatings to be of value.

Dry Film Lubricants - Remember, simply stated, friction horsepower is the arithmetic difference between indicated horsepower and brake horsepower. Therefore, the lower the friction horsepower, the higher the brake horsepower. So, by the use of dry film lubricants in areas that will net a reduction in friction horsepower, you can expect net power gained at the flywheel. Also expect a reduction in both surface and component operating temperatures. Applicable parts include valve springs, engine bearings, camshafts, and piston skirts and pins. Once again, you have the options of either selecting precoated parts or consulting with one of the coatings providers. Should you decide on the first option, it's wise to spend time talking with the manufacturer about the material (and its benefits) on any precoated component.

In this section, it may be helpful to discuss the benefits from coating certain major engine components. We'll include a few reasons and their basis, too. Our intention here is to stimulate some thoughts to the extent you'll begin to identify other parts and how they may benefit from coatings that address specific problems.

Valve Springs
- Smokey once contended that valve springs raise the operating temperature of engine oil more than combustion heat. He'd already discovered that with his own version of today's "Spintron" spin fixture. Included in that discussion was his belief, other than valve float, that heat foreshortens spring life more than anything else.

Essentially, there are two sources of heat in a valve spring. One is derived from the friction of a spring moving against other surfaces (inner springs, harmonic dampers, etc.) and the other from the "flexing" or "working" of spring material during normal operation. Studies have shown that a valve spring is never motionless, even when the valve is seated. Residual energy and harmonics traverse an otherwise "static" spring, while the valve is on its seat. Consequently, heat within spring material is continually being generated. Heat is a principle source of damage to springs and, since valve springs are cooled by oil, you can expect other parts of the engine to correspondingly experience increased oil temperature.

most shops that, customize pistons round off any sharp edges, cut the piston valve clearance, notches and polish the pistons to reduce heat absorption and reduce detonation, and some coat the pistons coat the top surface with a thermal barrier coating, some match it with a combustion chamber thermal barrier coating , the coating your showing is designed to hold oil and reduce friction

you might want to read thru these threads and their sub links







oil shedding coating on the under surface of the piston designed to speed heat transfer and reduce oil retention to reduce weight


outer skirt coating designed to increase wear resistance and retain oil film


Staff member

25050 Lifter Valley Oil Baffle, Small Block Chevy, including 18° heads Only $33.99
* Increases horsepower by shielding bottom of intake manifold from hot oil
* Keeps surplus oil out of valve covers by eliminating oil splash
* Maintains oil pressure during pushrod or rocker arm failure by keeping lifters in their bores (except with roller cam)
* Due to slight variation in blocks, the baffle may have to be trimmed .060 - .100" before it will "snap" into place
* Cannot be used with roller lifters

btw there ARE thermal coatings that can be applied similar to powder coating that can be used to low heat transfer rate barrier spacers to insulate the carb from engine heat on the intake



and low heat transfer carb spacers and air gap intake designs






lets take that piston as an example,they look great! but from an engineering stand point, rounding off a few sharp edges in the valve notch area,and getting it coated with a heat barrier thermal coating could be a useful step in reducing the engines potential to get into detonation

BAMBAM said:
If you've ever purchased a set of aftermarket forged pistons, usually, you'll notice how shiny and sharp they are compared to your OEM cast pistons. What's probably going through your mind is that they look really nice; nice and polished that is. However, these shiny surfaces can have an ill effect as they reflect energy much like a mirror does with light. One of the first and easiest tricks with pistons is to lightly sand the piston top to a super smooth, but dull finish. This can be accomplished using a 2000 grit piece of sand paper and dry sanding the piston domes/valve pockets. However, make sure this is done carefully. It's not a good idea at all to sand the skirts of the piston as this can cause scratches in the cylinder walls and cause oil consumption.
Now, by sanding the piston tops, you've just dulled this reflective surface, thus creating more area for the reaction to be absorbed and applied directly to the crankshaft. The resulting effect is increased thermodynamic effiency, better heat dispersion, and a piston with a greater defense towards detonation.
Another secret is to remove the sharp angles and edges on the piston dome surface. You might think your new Wiseco's or CP pistons are beautiful and because so, you're reluctant to cut them up. But, it's actually beneficial to remove those sharp edges. These sharp edges can create hot spots, and subsequently a think called "detonation". Now to accomplish this task, you'll need a die grinder and a light carbide roll to do this work. A dremel tool and a coarse carbide cutter will work just as well. Holding the piston by hand, take the die and lightly round off the sharp angles on the piston dome near the valve recesses and indents as well as the dome itself. I also like to wrap the skirts in blue painters tape to ensure that I don't knick the pistons if for some reason my hand slips. Now, don't remove too much material or you will start affecting the compression ratio. Next, sand the areas you remove material from, again with 2000 grit sandpaper to dull them up again.

Last but not least, another way to squeeze a couple more horsepower, as well as improving your motors resistance to detonation is to have the piston domes coated with a ceramic thermal barrier. This effectively distributes heat evenly across the piston dome and increase combustion temperatures. Heat makes power. The more heat you can generate in the cylinder, the more power the engine will potentially make. Unfortunately, internal combustion engines are thermodynamically inefficient by nature when it comes to heat. Most of the energy escapes through your exhaust system or it gets absorbed through your engine and by the cooling system. For obvious reasons, you can’t eliminate your exhaust system, and the cooling system is a mandatory component to keep the internal parts from melting or coming apart due to extreme heat levels. The only thing we can do to make an engine more thermodynamically efficient is to better contain and manage the heat that’s made when combustion occurs. That’s the purpose of thermal barrier coatings. Increased combustion temperatures and evenly dispursed heat is an easy way to increase thermodynamic efficiency, I.E. power. A good company for this is Swain-Tech coatings. Search for them on Google.

When it's all said and done, it would be smart to have the piston assemblies balanced for proper harmonics. It's good practice to do so in engine building. Also, be sure to remove all sanding particles. You don't want those getting wedged between a bearing and your crank or splashed on your cylinder wall.

A new coating from Techline is designed to provide multiple benefits such as thermal barrier (piston crowns), friction reduction (piston skirts), ring seal, and oil temperature control (piston pin bosses)-all in one coating. ... index.html

about the ONLY area where cast iron heads tend to have some advantage is that in general cast iron casting tend too have on average a denser less porous surface,
thats more time consuming to smooth and polish, but one thats easier bring to a semi-mirror finish, that the often more porous aluminum head castings..
you can save a great deal of time and effort and BOOST horse power with the application of thermal combustion chamber coatings,
the slightly porous as cast or mildly polished combustion chamber surface allows the coating to get a better mechanical grip on the heads combustion chamber.
the thermal barrier is a bit similar to a thick paint that bakes onto the surface forming a semi shiny wax like appearance, a bit like powder coating finishes, but the higher heat rated thermal coatings tend to be marginally duller in appearance.
but like porcelain its quite hard and heat reflective.
on the plus side it greatly reduces the heat transfer rates from the combustion chamber too the cylinder heads and that heat tends to boost power,
ESPECIALLY, with nitrous or TURBO use.



In addition to piston dome coating, the same high-temperature heat-barrier coating may be applied to the combustion chamber, all valve faces, exhaust valve throats, and exhaust valve ports. This completely encapsulates the combustion stream path. (This head was coated by Dart.)

All of the coating shops offer thermal barrier dome coating and anti-friction skirt coatings. Here’s an example of a piston treated with a thermal barrier coating on the dome and moly-coating on the skirts.
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