Manley Subaru EJ257 99.55mm +.25mm Bore 8.5:1 Dish Platinum Series Piston Set with Rings

If you're rebuilding the engine in your Subaru EJ257, these Manley Performance Platinum Series pistons are a solid choice for building a strong, reliable powerplant. These are forged pistons, meaning they start as a solid block of aluminum that's heated and then hammered into shape under immense pressure. This process creates a much stronger and more durable piston than cast aluminum, which is crucial for high-performance applications or when you need your engine to last. Manley uses a domestic 2618 alloy for these forgings, known for its strength and ability to handle the stresses of performance engines.

Manley has put a lot of thought into the design of these pistons. They feature proven cam and barrel skirt profiles, which are carefully shaped to help the piston move smoothly within the cylinder bore. This design helps reduce friction and wear on the cylinder walls, contributing to both power and longevity. The ring lands and grooves are machined to very strict tolerances, which is key for getting a good seal between the piston rings and the cylinder wall. A tight seal means better compression, more power, and less oil getting into the combustion chamber.

This set includes tool steel wrist pins, which are strong and durable. Manley's unique manufacturing process ensures that the ring grooves are perfectly square to the piston skirt, which further enhances the ring seal. These pistons have a dish shape and a compression ratio of 8.5:1, which is suitable for boosted applications where you need to control detonation. Keep in mind that these pistons are not CARB approved and cannot be shipped to California. They are designed for serious engine builds and are a popular choice among professional engine builders and tuners.