What is the compression ratio of these pistons?

These pistons feature a dish design that results in a compression ratio of 8.5:1. This is lower than stock, making them suitable for boosted applications where higher compression could lead to detonation.

What material are the pistons made from?

The pistons are forged from 2618 alloy, a strong and durable material commonly used in high-performance engine components. This alloy is chosen for its ability to withstand the stresses of demanding engine operation.

Are these pistons compatible with all EJ257 engines?

This specific piston set is designed for the 2004-2012 Subaru Impreza WRX STi with the EJ257 engine and features a 99.5mm bore. It's important to confirm your engine's exact specifications before ordering.

Specifications

Brand: Manley Performance
Part #: 621000C-4
UPC: 807298067933

Manley 04+ Subaru WRX STi (EJ257) 75mm DE-STROKED 99.5mm STD Bore 8.5:1 Dish Piston Set with Rings

Name: Manley 04+ Subaru WRX STi (EJ257) 75mm DE-STROKED 99.5mm STD Bore 8.5:1 Dish Piston Set with Rings
Brand: Manley Performance
SKU: manley-performance-manley-04-subaru-wrx-sti-ej257-75mm-de-stroked-99-5mm-std-bor-t14-244134
Price: 758.81 USD
Availability: BackOrder

$758.81

On Backorder

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

Fits 2004-2012 Subaru Impreza. Manley forged piston set built for performance and durability.

Key Features

Fits 2004-2012 Subaru Impreza.
Forged from domestic 2618 alloy for superior strength and performance.
Features proven cam and barrel skirt profiles that help generate power while being gentle on cylinder walls.
Ring lands and grooves are machined to exacting standards for enhanced ring seal.
Includes premium tool steel wrist pins for added durability.
Unique fixturing allows for skirt turning and ring groove machining in a single operation for ultimate squareness.

⚠️ 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

Manley Performance is well-known for building strong engine components that professional builders trust. If you're working on a 2004-2012 Subaru Impreza WRX or STi with the EJ257 engine, this set of de-stroked pistons is designed to handle serious performance upgrades. These pistons have a 99.5mm bore and an 8.5:1 compression ratio, making them a solid choice for building a more powerful engine.

These pistons are forged from 2618 alloy, a material chosen for its strength and ability to perform under high stress. Manley uses proven cam and barrel skirt profiles that help generate power efficiently while also being considerate of your cylinder walls during operation. The ring lands and grooves are machined to very precise standards, which is crucial for getting a good seal from your piston rings and maximizing the power your engine can make. They also come with tool steel wrist pins for added durability, and Manley's unique machining process ensures the ring grooves are perfectly square to the piston skirt.

This set includes the pistons, rings, and tool steel wrist pins. Please note that these pistons are not CARB approved and cannot be shipped to California. Always refer to the manufacturer's installation instructions for proper fitment and assembly procedures.