ACL 5M8309HXOS2-STD +0.002" Oversize Race Main Bearing Set for Subaru EJ

Vehicle Fitment

• Subaru 4-cyl EJ-series: EJ18, EJ20, EJ22, EJ25 (thrust in #5 position)

Features

• Race-series tri-metal construction for durability and fatigue resistance
• +0.002" housing oversize (OS2) for machined or line-bored blocks
• Extra clearance (HX spec) for high-stress or high-RPM builds
• 3/4-groove main bearings optimize oil flow and load distribution
• Increased eccentricity for stable hydrodynamic oil film
• No flash plating on back to improve heat transfer to the block
• Enlarged ID chamfers to accommodate performance crankshafts
• Tight wall tolerance ensures consistent bearing clearances

Specifications

• Part Number: 5M8309HXOS2-STD
• Bearing Size: Standard (STD)
• Housing Size: +0.002" (OS2)
• Oil Clearance: Extra (HX spec)
• Half Type: Identical upper/lower shells
• Material: Tri-metal (steel backing, copper-lead intermediate, lead/tin overlay)
• Shaft Diameter: 59.984-60.000 mm
• Tunnel Diameter: 64.000-64.020 mm
• Max Wall Thickness at Crown: ~1.992 mm

Included Components

• 5x main bearing shells (full set for one EJ-series engine)

Product Description

The ACL 5M8309HXOS2-STD is a high-performance main bearing set for Subaru EJ-series engines. It features a +0.002" housing oversize (OS2) for blocks that have been machined or line-bored, combined with extra HX clearance for high-RPM or modified applications.

Made from tri-metal material, these bearings provide excellent durability under racing or high-load conditions. The 3/4-groove design optimizes oil flow and load distribution, while increased eccentricity helps maintain a stable oil film even under extreme stress.

Ideal for performance builds on naturally aspirated or turbocharged Subaru EJ engines, this set ensures precise fitment, reliable lubrication, and long-lasting performance for demanding street or motorsport applications.