I have researching the benefits of the ceramic piston crown coating on the market today. I have spoke with tech support at Swain, Polydyn, and Embee and found each of them extremely helpful, knowledgeable, informative.

For the meager cost of the process (approx. $20 & up, per piston crown) and the potential list of benefits:

- decreased detonation
- increased power and combustion efficiency
- decreased carbon build-up
- increase structural integrity of the piston*
- greatly increased piston durability

I honestly can't understand why every single one of us isn't coating our piston crown's, including those of us with stock STI pistons, etc.

So here's my question - Am I missing something? Is there a hidden downside to this process I don't know about? We're all spending gob's more $$ on mods without nearly this level of benefit, so is this process really as good as it sounds?

* Embee told me that their EPC 100 process nearly doubles the "strength" of the base piston material. I didn't ask Embee to back up their claim a hte time, but I think I will request any available date. Also note this particular process requires a .002 overbore.
* A very knowledgeable tech at Polydyn told me their coatings not only reflect heat (thereby keeping the operating temperature of the piston within it's design limit) but also increases the structural integrity of the base material itself.
* Swain made no claim that their ceramic coating increased the strength of the base piston material.

For those who want to read further, here are the links -

http://www.polydyn.com/coated_pistons.htm

http://www.embeeperformance.com/coatings/thermal_barrier.html

http://www.swaintech.com/store.asp?pid=10963

I suppose if the piston remained cooler while in operation then it would be stronger than the same piston running at a much higher operating temperature due to lack of ceramic coating. As far as actually changing base material properties I wouldn't buy it. I wonder if you could run tighter PSW clearance with a coated piston due to this.

thermal coatings, dissipate heat.
i would doubt increase structural strength.


- decreased detonation
- increased power and combustion efficiency
- decreased carbon build-up
- increase structural integrity of the piston*
- greatly increased piston durability..i seriously doubt this..

but swaintech was the most honest...

Ceramic piston coatings have many benifits...
The coating does not improve the strength of the piston per say, but it does keep it from degrading...

Depending on the alloy used to make the piston, the aluminum will start to change its physical properties once a certain temp is reached....
This temp can be between 425 and 575 depending on the alloy...

When this happens, it is usually a certain part of the piston that this happens to, commonly called a hot spot...

When the piston top is coated with ceramic, it is a lot harder to get a hot spot to form due to the speed that the ceramic moves heat, and the fact that a lot of combustion heat is reflected back into the chamber to begin with....

This even heat distrubution helps prevent preignition that is normally caused by hot spots on the piston crown of an uncoated piston...

I guess you could say that the piston has more durability than a non-coated piston, but only in the same setup/tune... It all comes back to the temp that the aluminum reaches... If it gets to hot, the aluminum changes properties, and it will be downhill from there...

There are downfalls to having the coating as well...

If it flakes off from overheating the aluminum (which starts to change the aluminums properties, degrading the bond of the ceramic coating) or knocking, you will probably get an instant hot spot because you tuned it more agressively because the coating allowed it, not to mention that ceramic is now flying around and on the way out the exhaust...

Many companies now have coatings that expand at, or very close to the same rate as certain alloys due, but that doesn't mean it will stay on the piston crown... (There are different coatings for different alloys...)

I know plenty of people that don't like ceramic coated pistons...
But I do...

I use ceramic coated pistons on just about every performance engine I build... :)

At my work we study alloys and materials for their changing properties i'd like to see a piston thats been used that has the ceramic coating vs the regular piston after a given period of time i'd put it on the CMM at work and i could tell you actual data by probing all of the surfaces

from the Polydun web site -

PolyDyn ceramic piston coating not only protects the piston, but it makes the piston stronger and more efficient by significantly enhancing the structural integrity of the piston dome.

and the coating that Embee told me nearly doubled the strength of their piston was a two step process, the first step being a proprietary hard anodize treatment -

EPC 100 is similar to hard anodizing. The .002 dimensional change, increases piston life and H.P. by evenly controlling part expansion while reducing friction and part temperature. This coating can be applied to new or used pistons. When being applied on new pistons, we recommend that pistons are machined to allow for the added dimensional change in the ring grooves. But if this is not desired we can mask the parts to maintain the current dimensions

from the Polydun web site -

PolyDyn ceramic piston coating not only protects the piston, but it makes the piston stronger and more efficient by significantly enhancing the structural integrity of the piston dome.

and the coating that Embee told me nearly doubled the strength of their piston was a two step process, the first step being a proprietary hard anodize treatment -

EPC 100 is similar to hard anodizing. The .002 dimensional change, increases piston life and H.P. by evenly controlling part expansion while reducing friction and part temperature. This coating can be applied to new or used pistons. When being applied on new pistons, we recommend that pistons are machined to allow for the added dimensional change in the ring grooves. But if this is not desired we can mask the parts to maintain the current dimensions

They are not the only company that uses sulfuric acid baths to open the pores of the aluminum up...

They are not the only company that uses sulfuric acid baths to open the pores of the aluminum up...
Annodizing is neat because it leaves a layer of aluminum oxide on the piston. Aluminum oxide is harder than hell and really increased scuff and wear resistance.

with the added heat dissapation into the combustion chamber wouldnt that kinda defeat the idea of ceramic coating the tops of the pistons? i can see skirt coating very good to do but coating the tops doesn't make sense.

You coat the combustion chamber also, same for the valve tops and exhaust ports.

I've read somewhere that if all of the above are done, the engine is more prone to detonation because all the heat stays inside de cc and is not dissipate thruout the engine.

I'm planing to ceramic coat everything and use a water/methanol injection system.