Investment Insurance: Benefits Of Piston Coatings In An Engine Build

In the performance engine scene, it has been said that coatings on pistons are the magic sauce to keep it alive. No matter how much nitrous you use, the big boost numbers you try to slam in there, or even if a tune-up isn’t spot on, this can save the day. We’re here to tell you that that isn’t exactly the case but it can help.

We want to share with you how and why piston coatings can help you get through rigorous days of heavy towing, sled pulling, or record breaking drag racing passes.  There are several different types of coatings. Some are designed to be heat barriers while others coatings are designed to be dry film lubricants. With the help of MAHLE Motorsportwe’ll break down the options out there for you to choose from.

MAHLE offers multiple configurations of pistons for all three of the diesel engine brands. With each of those options, you have the opportunity to utilize their special coatings. We caught up with MAHLE’s Joe Maylish to talk about their different coating options and why they are necessary when it comes to an engine build.

This ceramic-based thermal barrier application greatly reduces heat transfer for improved performance and adds a layer of insulation to the piston crown to protect against thermal shock. For added protection and performance, this cutting edge thermal coating is particularly important for use on the crown to prevent hot spots.

If you’re building an engine that you plan on using nitrous oxide with, this is a scenario where you could benefit from these coatings. “The coatings aren’t a bandaid that allow you to get by with a poor tuneup. These coatings are basically widening your range of abuse,” Maylish said. “The advantage of coatings is they can buy you some time. If you push an engine to the point where it would normally scorch the tops of pistons, the coatings will take the abuse before it damages the piston.”

Now, if you abuse this engine far past the point of the coatings, you will inevitably hurt the engine. This is why having a good tune-up in the truck is critical. The coatings will protect your investment and potentially save you big time.

With the amount of pressure these diesel engines see, protection is an absolute must. If you’re already spending the money on pistons, why not use some extra coin and insure that investment? Coatings on diesel engines include an element called Grafal. The Grafal acts as an anti-friction material and is screen printed onto the surface of the piston.

This coating is used to reduce drag like many other skirt coatings, but this is where the similarities end. The screen print application provides superior adhesion and is designed to last 100,000 or more miles. The unique properties of Grafal reduce the harsh contact between the piston skirt and cylinder bore, resulting in much less wear on the bore and significantly reduced piston skirt fatigue.

The Three Main Coatings

Depending on what you’re doing, there are three different coatings that you can have applied to your piston order. There is a thermal barrier coating that you typically see on the crowns of the pistons, an anodized or nickel-plated coating on the ring grooves that will result in ring protection, and then lastly, the skirt coatings.

With the skirt coatings, there are different variations of coatings. There are coatings that are meant to be for break in periods, coatings that are abradable and applied thick which allow the pistons to find their own thickness and clearance correctly, and then there are coatings that are applied that are meant for the life of the engine that feature friction reduction capabilities and protection against scuffing.

All 6.0-liter, 6.4-liter, and 6.7-liter Power Stroke pistons, as well as many Duramax and Cummins pistons come with this Grafal coating from the factory, and it is not uncommon to tear these engines apart with over 250,000-miles on them with the skirt coating still in great shape.

“While these skirt coatings may look the same on the outside, they may be applied for completely different reasons,” Maylish said. “The friction reduction coating is applied in all of our OE parts as well as the top-of-the-line race engine components. As long as everything in that engine is perfect, these coatings will last as long as the piston does.”

Getting an engine to “perfect” condition is not easy and that is the best part about these special coatings. They will take the abuse and save you from that time you beat the engine too hard or got areas too hot. If you get into a spot where you’re lacking lubrication, before the cylinder sees scuffing, the coating will buy you that time.

If you’re in the market for pistons, you should really consider piston coatings.

Moving on, let’s talk about the top ring groove protection. Like we mentioned earlier, there is a nickel-plated coating and a hard anodized coating. MAHLE suggests using the hard anodized coating on this because of its better protection against micro-welding.

Micro-welding is where the combustion pushes that ring down and seals as it should, but at high temperatures, you can actually see localized melting of the aluminum which will tear up the surface of the ring groove. Since that is where you’re wanting a good seal, this protection is a must.

For information about MAHLE Motorsport and their piston coating options, head on over to their website here. For more tech articles, stay tuned right here to Diesel Army. What do you think about the thermal barriers? Seems like affordable insurance for an engine that you’ve sunk quite a bit of money into anyway, right?


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About the author

Artie Maupin

Artie Maupin is from Southeast Missouri and has an extreme passion for anything diesel. He loves drag racing of all kinds, as well as sled pulling competitions.
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