Wiseco K631M865 Forged Piston Kit for 2002-2006 Acura/Honda K20A / K20Z

Vehicle Fitment

• 2002-2006 Acura RSX Type-S / Honda K-Series engines (K20A, K20Z, some K24)

Features

• Forged 2618 aluminum for maximum strength and durability
• ArmorGlide® low-friction skirt coating to reduce wear and noise
• Flat-top crown with -3.4 cc volume for precise compression tuning
• Strutted forging design for enhanced rigidity
• Precision ring grooves, anti-detonation groove for better sealing
• Forced pin-oiling helps maintain strong lubrication at high RPM
• Comes with full piston ring set (8650XX)
• Includes 22 mm floating wrist pins and locks

Specifications

• Bore: 86.50 mm
• Compression Height: 30.00 mm
• Piston Volume (Dish): -3.40 cc
• Compression Ratio: ~9.6:1
• Wrist Pin Diameter: 22 mm
• Piston Material: Forged 2618 aluminum
• Piston Set Quantity: 4
• Typical Piston Weight: ~316 g

Included Components

• 4x forged pistons
• 4x 22 mm wrist pins
• 1x high-performance ring set (8650XX)
• Circlips / wrist-pin retainers

Product Description

The Wiseco K631M865 is a professional-grade piston kit made for Honda's K-series engines - especially the K20A and K20Z found in Acura RSX and other performance models. These pistons are forged from 2618 aluminum, giving them strength to handle high-RPM and tuned applications.

With a flat-top crown and a small dish of -3.4 cc, the pistons create a compression ratio of around 9.6:1 - a sweet spot for both naturally aspirated builds and mild performance tuning. The strutted-forge structure ensures rigidity under stress, and the ArmorGlide® coating lowers friction to prolong piston life. Forced pin-oiling supports reliable lubrication of the 22 mm wrist pins even under heavy loads.

This comprehensive kit includes pistons, rings, and pins - all you need for a solid, high-performance engine build. For best results, install with precision: check ring gaps, verify clearances, and follow proper torque specs to ensure durability and performance.