Coatings to enhance both performance and longevity are the centre of focus in the world of racing piston manufacture today. To learn more, particularly in a NASCAR context, we talked with Brad Green, an engineer at Mahle Motorsports in Fletcher, North Carolina.
According to Green, all their coating manufacture is performed in-house. This, he told us, can provide shortened lead times and reduced costs when compared to shipping pistons to outside coating sources. It also “gives us much greater control over maintaining tight tolerances and ensuring our customers get the best system for their application.”
The wide variety of custom pistons produced for the NASCAR market typically have the company’s Grafal coated skirts and hard anodised ring grooves, Green explained. This particular pattern on the skirt provides dynamic oil control in the piston skirt and cylinder wall interface.
“We maintain ultra flat tolerances on the ring grooves – whether or not they are anodised. The anodising [of pistons] presents special challenges in maintaining the groove quality, in order to provide the optimum sealing of the piston, ring and cylinder bore power cell,” he said.
Green notes that their Ferroprint coating, for use with aluminium cylinder bores, “is embedded with iron particles, thus allowing an aluminium piston to run against an aluminium liner.
“Typically,” Green continues, “if similar materials are run against one another in this type of fashion, the end result would be the piston ultimately friction-welding itself to the liner. With the advent of this coating, that isn’t the case. The engine builder can, in turn, reduce the mass of the overall engine package as a result of [using] this simple coating.”
The company recently received patent approval for creating a patterned skirt coating for its racing pistons. The pattern enhances dynamic oil control along the piston skirt, resulting in increased efficiencies of the piston-to-liner interface, according to Green.
“In using our new compressible Grafal coating, the patterns would also allow coating of specific highly loaded areas of the piston skirts to help eliminate issues with secondary motion, as the piston changes direction.
“This compressibility helps to reduce overall stress in the piston, potentially resulting in greater durability.” While this technology is still in its initial implementation for NASCAR stock car applications, “The benefits are readily apparent.” Using these new patents, “This is yet another feature to set us further apart as we continue to demonstrate our efforts remain on the leading edge of technology.”
Written by Anne Proffit.