Wiseco ArmorPlating: For Heat, Detonation, and Durability

May 17, 2017 / by Robert Poole

Wiseco offers ArmorPlating and ArmorGlide on its line of pistons. What is it, and why do you need it? Keep up to date on the latest plating technologies including ArmorPlating!

An internal combustion engine has a lot of moving parts, but the parts that may take the most severe abuse are the pistons. They are subject to the extreme changes in speed and motion of the two- and four-stroke cycle, the intense heat of combustion and resultant pressure, and the occasional abuse of detonation that tries to either tear the piston apart or burn a hole through it.

“Unlike other metal plating that lose hardness and soften when exposed to heat, this plating actually gets harder as it runs.”—Dave Fussner, Wiseco R&D Manager

Anytime you can reduce friction of any kind in an internal combustion engine, it’s a good thing for both heat management, oil temperature, and power production. ArmorPlating applied to the piston pin bore reduces friction in this normally high-friction area. (Left) The left piston was used in a popular 24 road race under the severist of racing conditions. Look at well the pin bore is wearing compared to the new piston on the right. (Right) Close up shot of the used piston's pin bore.

All pistons made of aluminum but high quality pistons, like those manufactured by Wiseco, use more involved manufacturing processes, better and stronger material, incredibly intricate machining processes, and occasionally plating to help them survive and thrive in the unforgiving environment of a combustion chamber, compared to less expensive, high-volume cast pistons. We won’t get into all of the choices in alloys and manufacturing techniques since that could fill a book on its own, and instead concentrate on the exciting new piston plating available from Wiseco, specifically ArmorPlating.

After decades of research, Wiseco brewed up its own subset of one of the three broad categories of metal-based auto catalytic plating, trademarking it as ArmorPlating. This plating is applied to the piston domes, ring grooves, and wrist pin bores of Wiseco pistons to provide an extremely low coefficient of friction, reduced piston ring blow-by, and detonation protection.

Wiseco’s R&D Manager Dave Fussner explained how their plating is different than others on the market, saying, “Unlike a lot of different metal plating, ArmorPlating does not lose its hardness with heat. In fact, it gains hardness when heated—it doesn’t soften with heat, it hardens. And that’s very useful on a piston dome.”

Another shot of the raced piston. ArmorPlating reduces blow-by of combustion gas past the pistons and rings by doing a far better job of sealing the top ring on the bottom of its ring groove, and maintaining that seal much longer, than an uncoated ring land.

Without giving away any of Wiseco’s highly protective, proprietary trade secrets, essentially a piston is coated with ArmorPlating, then the plating is machined off the skirts and lands, leaving the plating to protect and serve the piston pin bore, ring grooves, and piston top or dome. Fussner said, “From an aesthetic standpoint, when you pull these pistons out of the box you see this beautiful plating on the ring grooves, wrist pin bores and dome, and the beautiful shiny aluminum skirts where the plating is turned off. They look like gems when you take them out of the box, but that beauty is there for function.”

About that functional aspect, Fussner added, “ArmorPlating coats the piston with ultra precision in the ring grooves and pin bores, and it even coats blind holes. That is not achievable with any kind of process like chrome or electro plating. That is important in a ring groove because ring grooves are very precisely engineered and machined, and you don’t want to put a plating on there that doesn’t go all the way around [the groove] evenly.”

The plating is applied to the piston domes, ring grooves, and wrist pin bores and provides a lower coefficient of friction, less ring blow-by, and a measure of detonation protection. The piston is removed during the manufacturing process and coated, then it goes back into a CNC to get the skirt turned up to the accumulator groove. The ArmorGlide skirt caoting is a nice, complimentary plating.

So ArmorPlating is precise and makes for pretty looking pistons, but what is its main function? Once again, piston ring blow-by reduction, friction reduction and detonation resistance primarily. The reduced rotational friction offered by the ArmorPlating is a real benefit in the piston pin bore. The blow-by reduction comes as a result of a better “fit” between the rings and the ring grooves. Fussner said, “It significantly improves the lower edge sealing of the top ring groove, maintaining a very low amount of blow-by for a long time, compared to an uncoated groove. As an added benefit, it also eliminates microwelding of the top ring groove”

In regards to detonation, ArmorPlating doesn’t prevent detonation but it does protect the piston from erosion due to detonation. Fussner explained, “If you’ve ever removed a piston and it looked like it was sandblasted, with little pits on the dome—that’s the result of the beginning of severe detonation. If it kept on detonating, you were either going to blow the land off a ring groove or rip the top of the piston off. Or it might just burn a hole straight through the piston. The ArmorPlating has a great amount of resistance to this erosion. The plating won’t keep the piston from breaking, but it combats erosion from detonation.”

Carbon buildup as a result of combustion is common on an uncoated piston dome. The richer the air/fuel mixture the more carbon buildup happens, and that will effectively increase the compression ratio (by reducing chamber volume) leading to increased detonation. Wiseco’s ArmorPlating makes it difficult for carbon to 'take hold,' all but eliminating the problem of carbon buildup.

He also pointed out that with the ArmorPlating plating, carbon has a very difficult time adhering to the piston dome. That means that the piston won’t develop carbon buildup that leads to an increased compression ratio and therefore even more detonation. It also allows the domes to run 20 degrees C cooler and reflect heat back into the chamber for better combustion efficiency.

ArmorPlating is used on the higher-end pistons in Wiseco’s line and it’s making its way onto more and more “mainstream” pistons. Of course it’s available on all the company’s custom pistons as well. On the latter, Fussner said, “Custom pistons are almost like ordering food ala carte; do you want ArmorGlide skirt plating? ArmorPlating? There are options to add or delete when specifying custom pistons.”

When asked if there is an application that would not benefit from ArmorPlating, Fussner replied, “I can’t imagine a situation where you wouldn’t want to use it.”

So there you have it. If you want the best anti-friction, lowest piston ring blow-by  and detonation protection piston plating that Wiseco offers, make sure to order your pistons with ArmorPlating—ArmorGlide for the skirts—for the ultimate in beautiful and functional pistons.


Topics: featured, PISTONS 101, ENGINE TECH

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Written by Robert Poole