What is the advantage of using forged pistons like these Manley pistons?

Forged pistons are made from a solid block of aluminum that is heated and hammered into shape. This process creates a much stronger and more durable piston compared to cast pistons, making them ideal for high-performance and high-boost applications where extreme stress is placed on the engine components.

What does the +.25mm size indicate for these pistons?

The +.25mm designation means these pistons are slightly larger than the standard bore size. This is used when an engine block has been bored out to correct imperfections or to increase displacement, and these pistons are designed to fit that specific, slightly larger bore.

Are these pistons compatible with all exhaust and intake systems?

These pistons are internal engine components and do not directly interface with exhaust or intake systems. However, their design is intended to work with performance-oriented engine builds, so they are generally compatible with aftermarket intake and exhaust modifications that are designed for the EJ257 engine.

Specifications

Brand: Manley Performance
Part #: 632402CE-4
UPC: 807298089447

Manley 04+ Subaru WRX/STi (EJ257) 83mm Stroke 99.75mm +.25mm Size B 8.5:1 CR Extreme Duty Piston Set

Name: Manley 04+ Subaru WRX/STi (EJ257) 83mm Stroke 99.75mm +.25mm Size B 8.5:1 CR Extreme Duty Piston Set
Brand: Manley Performance
SKU: manley-performance-manley-04-subaru-wrx-sti-ej257-83mm-stroke-99-75mm-25mm-size--t14-28528
Price: 963.51 USD
Availability: BackOrder

$963.51

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Manley 04+ Subaru WRX/STi (EJ257) 83mm Stroke 99.75mm +.25mm Size B 8.5:1 CR Extreme Duty Piston Set. Built for high-performance engine builds.

Key Features

Fits 2004 and later Subaru WRX/STi with EJ257 engine.
Forged from domestic 2618 alloy for superior strength and performance.
Features proven cam and barrel skirt profiles for efficient power generation and cylinder wall protection.
Exacting standards for ring lands and grooves ensure enhanced ring seal and more power.
Includes premium chrome moly wrist pins for added durability.
Piston size is 99.75mm with a +.25mm overbore.

This piston set is designed for 2004 and later Subaru WRX and STi models equipped with the EJ257 engine. Please verify fitment for your specific vehicle.

⚠️ CA WARNING: This product can expose you to chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm. Learn more

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About this part

Product Details

If you're rebuilding the engine in your 2004 and later Subaru WRX or STi with the EJ257 engine, you're likely looking for pistons that can handle serious power. These Manley Extreme Duty pistons are built for just that. They're designed to be a direct replacement for your stock pistons, but with a significant upgrade in strength and performance for boosted applications.

Manley uses domestic 2618 alloy forgings for these pistons, which are known for their exceptional strength and ability to withstand high temperatures and pressures. The pistons feature proven cam and barrel skirt profiles, which help them generate power efficiently while also being gentler on your cylinder walls. This design, combined with exacting standards for ring lands and grooves, ensures a better ring seal, leading to improved power output and engine efficiency. The unique fixturing Manley uses allows them to machine the skirt and ring grooves in one operation, ensuring they are perfectly square to each other for optimal performance.

This set includes tool steel wrist pins for added durability, and the pistons are sized at 99.75mm with a +.25mm overbore, featuring an 8.5:1 compression ratio. Keep in mind that these pistons are not CARB approved and cannot be shipped to California. For a high-performance engine build where reliability and power are key, these Manley pistons are a solid choice.