Piston skirt coatings from various manufacturers are entering the industry hot and heavy over the last several years, and the newest one we’ve seen is the Line 2 Line coating presented by Icon Pistons at SEMA 2015.
Unlike other finishes we’ve seen, Line 2 Line is an abradable powder coating, which is polymer-based and engineered to be applied thicker on the piston than liquid-style coatings.
Since the coating is thicker, it’s designed to hone in to the ideal oil film clearance during engine break-in, and then stop wearing. As the piston expands during operation, the coating will again contact the cylinder wall, where it’s designed to buff the cylinder wall and maintain this clearance. This allows the piston to operate at a tighter running clearance, which means the piston will rock less in the bore and maintain optimal ring seal.
The coating is ideal for high-expanding 2618 aluminum alloy pistons that require larger clearances. As the cylinder bore can be built tightly to the piston, and the coating then wears itself into the barrel, it finds and maintains the ideal geometry under running conditions.
Piston break-in helps to account for slight variations in manufacturing tolerances, thermal distortion, and operating stress, so in the end, the piston is fine-tuned for best performance.
They also explain that the shock loading and degradation of the piston, connecting rod, and bearing assembly is reduced.