What does '100mm Bore Over Size .5mm' mean for my engine?

This means the pistons are designed for an engine cylinder that has been machined to a 100mm diameter, which is 0.5mm larger than the original bore size. This is typically done during an engine rebuild to restore cylinder walls or to increase engine displacement.

What is the benefit of the cam and barrel skirt profiles?

These profiles help the piston move more smoothly within the cylinder bore. This design reduces friction and minimizes wear on the cylinder walls, contributing to better engine performance and longevity.

Are these pistons suitable for all types of Subaru EJ25 builds?

These are Extreme Duty pistons, built for high performance. The flat-top design is versatile, but their robust construction makes them ideal for builds aiming for increased power and durability, often found in modified or competition engines. They are not CARB approved and cannot ship to California.

Specifications

Brand: Manley Performance
Part #: 632105CE-4
UPC: 807298089249

Manley Subaru EJ25 100mm Bore Over Size .5mm Extreme Duty Flat Top Piston Set with Rings

Name: Manley Subaru EJ25 100mm Bore Over Size .5mm Extreme Duty Flat Top Piston Set with Rings
Brand: Manley Performance
SKU: manley-performance-manley-subaru-ej25-100mm-bore-over-size-5mm-extreme-duty-flat-t14-81536
Price: 963.51 USD
Availability: BackOrder

$963.51

On Backorder

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

Manley Subaru EJ25 100mm Bore Over Size .5mm Extreme Duty Flat Top Piston Set with Rings. Forged 2618 alloy for superior strength.

Key Features

Fits Subaru EJ25 engines with a 100mm bore, 0.5mm oversize.
Constructed from domestic 2618 alloy forgings for superior strength and performance.
Features proven cam and barrel skirt profiles to reduce friction and wear on cylinder walls.
Exacting standards for piston ring lands and grooves ensure enhanced ring seal and power.
Unique fixturing allows for skirt turning and ring groove machining in a single operation for ultimate squareness.
Includes premium chrome moly wrist pins for added durability.

This piston set is designed for Subaru EJ25 engines with a 100mm bore and is 0.5mm oversize. It is not CARB approved and cannot be shipped to California.

⚠️ 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

Forged from domestic 2618 alloy, these Manley Extreme Duty pistons are built to handle serious power for your Subaru EJ25 engine. They are designed with a 100mm bore and are 0.5mm oversize, meaning they're intended for engines that have been bored out to accommodate them, often during a rebuild where cylinder walls might have wear or for increased displacement. The flat-top design is common for naturally aspirated or mild turbo applications, offering a good balance of compression and piston volume.

Manley uses proven cam and barrel skirt profiles on these pistons. This design helps the piston move smoothly within the cylinder bore, reducing friction and wear on the cylinder walls while still allowing the piston to generate substantial power. The ring lands and grooves are machined to exacting standards, which is crucial for achieving a strong seal with the piston rings. This improved seal means less combustion pressure escapes past the rings, leading to more efficient power delivery and better engine performance. The unique fixturing Manley employs ensures the ring grooves are perfectly square to the piston skirt, a detail that contributes to overall engine longevity and reliability.

Included with this set are premium chrome moly wrist pins, known for their strength and durability. These pistons are a popular choice among professional engine builders and tuners who demand robust components for high-performance Subaru builds. Please note that these pistons are not CARB approved and cannot be shipped to California. They are designed for competition or off-road use where emissions regulations may differ.