Wiseco K579M925 Forged 92.5 mm -17.8 cc Pistons for Subaru EJ20 Stroker

Vehicle Fitment

• Subaru EJ20 (2.0 L) - 79 mm stroker crank, pre-October 1998 sleeved blocks
• Applications include Impreza WRX / STI and other EJ20 16-valve engines

Features

• Forged from 2618 aerospace-grade aluminum for high strength and durability
• ArmorGlide® skirt coating to reduce friction and resist scuffing
• Dish / -17.8 cc crown to lower compression - ideal for stroked or boosted builds
• Strutted forging design for added rigidity under high loads
• Fully machined crown and precise ring groove geometry
• Forced-pin oiling for reliable lubrication at high RPM
• Includes matched high-performance piston ring set (9250TX)
• Floating 23 mm wrist pins for secure rod-to-piston connection

Specifications

• Bore: 92.50 mm
• Compression Height: 30.00 mm
• Piston Dish Volume: -17.8 cc
• Wrist Pin Diameter: 23 mm
• Piston Material: Forged 2618 aluminum
• Piston Count: 4
• Ring Set: 9250TX
• Estimated Compression Ratio: ~8.5 :1

Included Components

• 4x forged dish pistons (92.5 mm, -17.8 cc)
• 4x 23 mm floating wrist pins
• 4x circlips / locks for wrist pins
• 4x performance piston ring sets (9250TX)

Product Description

The Wiseco K579M925 piston kit is designed specifically for Subaru EJ20 stroked builds (79 mm stroke), particularly in pre-October 1998 sleeved EJ20 blocks. The large 92.50 mm bore combined with a -17.8 cc dish gives a reduced compression ratio, making it suitable for high-performance or high-boost configurations.

Constructed from durable 2618 forged aluminum, these pistons are built for strength and longevity even under demanding conditions. The ArmorGlide-coated skirts minimize friction, while the strutted forging adds structural support. With matching 9250TX rings and 23 mm floating wrist pins, this kit ensures solid sealing and robust connection to the rods.

When installing, it's critical to verify bore-to-wall clearance, ring gap, and deck height. The dished design and lowered compression require careful selection of gasket thickness and chamber volume to reach the desired final compression ratio for your build.