What is the advantage of forged pistons over cast pistons?

Forged pistons, like these from Manley, are made from a solid block of alloy that is heated and hammered into shape. This process creates a stronger, more durable piston that can withstand higher temperatures and pressures compared to cast pistons, making them ideal for performance and modified engines.

What does the '+.1mm' bore size indicate?

The '+.1mm' designation means these pistons are designed for an engine block where the cylinder bores have been machined to be 0.1 millimeters larger than the original factory specification. This is typically done during an engine rebuild or when increasing displacement.

Are these pistons suitable for a turbocharged engine?

Yes, these pistons are designed for performance applications and feature a 10:1 compression ratio with a dish top, which is commonly used in turbocharged or supercharged engines to help manage combustion pressures and prevent detonation.

Specifications

Brand: Manley Performance
Part #: 632701C-4
UPC: 807298093161

Manley 2015+ Subaru WRX FA20F 86.1mm +.1mm Bore 10:1 Dish Piston Set of 4

Name: Manley 2015+ Subaru WRX FA20F 86.1mm +.1mm Bore 10:1 Dish Piston Set of 4
Brand: Manley Performance
SKU: manley-performance-manley-2015-subaru-wrx-fa20f-86-1mm-1mm-bore-10-1-dish-piston-t14-4386544
Price: 766.12 USD
Availability: BackOrder

$766.12

On Backorder — Expected to ship by May 3, 2026

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

Manley 2015+ Subaru WRX FA20F 86.1mm +.1mm Bore 10:1 Dish Piston Set of 4. Built for serious engine builds.

Key Features

Fits 2015+ Subaru WRX FA20F engines.
Set includes four pistons with a 10:1 compression ratio and dish top.
Pistons are forged from domestic 2618 alloy for strength and performance.
Features cam and barrel skirt profiles for smooth operation and power.
Exacting standards for ring lands and grooves ensure enhanced ring seal.
Includes premium chrome moly wrist pins.

⚠️ 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 robust engine components that serious builders trust. If you're working on a 2015 or newer Subaru WRX with the FA20F engine and need to rebuild or upgrade your pistons, this set is designed for that job. These pistons have a 10:1 compression ratio and a dish shape, which is a common choice for boosted applications where you want to control detonation.

These pistons are forged from 2618 alloy, a strong material that can handle the demands of performance engines. They feature cam and barrel skirt profiles, which help them run smoothly against the cylinder walls while still generating power. Manley also pays close attention to the ring lands and grooves, ensuring a tight seal for better combustion efficiency. The set includes premium chrome moly wrist pins, and Manley's unique machining process ensures the ring grooves are perfectly square to the skirt for optimal performance.

This set is for a +.1mm bore size, meaning it's intended for cylinders that have been honed out slightly beyond the standard size. It's important to note that these pistons are not CARB approved and cannot be shipped to California. If you're building a high-performance engine, these pistons offer a solid foundation.