Manley 04+ Subaru WRX/STi (EJ257) 83mm Stroker 100.0mm +0.5mm Size 8.5tDish Extreme Duty Piston Se

These Manley Extreme Duty pistons start with domestic 2618 alloy forgings, a material chosen for its exceptional strength and ability to handle high performance demands. They are specifically designed for the 2004 and later Subaru WRX and STi models equipped with the EJ257 engine, featuring an 83mm stroke and a 100.0mm bore size, with a +0.5mm oversize to account for machining. The 8.5:1 compression dish helps manage cylinder pressures in boosted applications.

Manley incorporates proven cam and barrel skirt profiles on these pistons. This design helps reduce friction and wear on the cylinder walls, contributing to both longevity and improved power output. The ring lands and grooves are machined to exacting standards, which is crucial for achieving a solid ring seal and maximizing combustion efficiency. This attention to detail ensures that the piston works harmoniously with the rings to keep combustion gases contained and prevent blow-by, ultimately translating to more power.

Included with these pistons are premium chrome moly wrist pins, known for their durability. For those seeking even greater resilience, Manley offers upgrades to 9310 or Turbo Tuff/DLC alloys on select part numbers. Manley's unique manufacturing process allows for skirt turning and ring groove machining in a single operation, ensuring the squareness of the ring grooves relative to the piston skirt. This level of precision is what professional engine builders and tuners rely on for superior performance and durability in demanding builds. Please note that these pistons are not CARB approved and cannot be shipped to California.