Wiseco's new asymmetrical piston forging design for the Mitsubishi Lancer Evolution 8-9 maintains a larger skirt area on the heavily stressed major thrust side, while reducing friction with a smaller skirt area on the minor thrust side. The result is a high strength, lightweight piston that significantly reduces friction in your engine.

What is asymmetrical?

Asymmetrical, by definition, means "not symmetrical". The new asymmetrical forged pistons from Wiseco utilize two different sized piston skirts, so are identified as an "asymmetrical" piston design.

Why are asymmetrical pistons better?

FACT: The two skirts of a piston do not experience the same amount of mechanical loading. During the firing cycle, the load exerted on one piston skirt, referred to as the "major thrust side," can be up to 10 times higher than the load experienced by the opposing skirt, referred to as the "minor thrust side." The disparity in skirt loading can vary in magnitude depending on key variables including the engine's stroke, rod length, and peak cylinder pressure.

Wiseco's asymmetrical pistons are designed to specifically handle the dissimilar mechanical loads experienced by both piston skirts. The resulting piston design features a large skirt area on the heavily loaded "major thrust side" and a small skirt area on the less loaded "minor thrust side". Overall, the piston design is stronger, yet lighter than previous designs.

The Wiseco asymmetrical Evo "shelf" pistons are available in a variety of compression ratios, bore diameters to suit a broad range of combinations.