King Engine Bearings MB5220XPSTDX XP Series Main Bearing Set Subaru - EJ20 EJ22 EJ25

The King Engine Bearings MB5220XPSTDX is a high-performance main bearing set engineered for Subaru EJ20, EJ22, and EJ25 engines found in WRX and STI models. Part of King's XP Series, these bearings feature advanced metallurgical and geometric technologies designed to handle extreme performance loads in racing and high-output applications.

pMax Black Tri-Metal Technology:

The XP Series features pMax Black, a proprietary tri-metal structure that is 24% harder than conventional tri-metal race bearings. This enhanced copper-lead construction includes a nickel barrier and SecureBond adhesion process for superior stability between layers. The 0.0005-inch metallurgically hardened performance overlay withstands greater loads and resists surface fatigue better than traditional bearing materials.

Key Performance Features:

• 15-30% Greater Load Capacity: Engineered for high-load, long-duration racing applications including circle track and off-road racing with forged steel aftermarket crankshafts
• Bull's Eye Tolerance: Industry-leading wall tolerances with all shells matched to 0.0001 inch for precise fitment
• Half-Grooved Main Design: Mains are half-grooved for uncompromised lower shell load capacity while maintaining proper oil distribution
• Improved Oiling: Enlarged, chamfered oil holes promote better lubrication under extreme conditions
• Medium Eccentricity: Optimizes load distribution and enhances oil film characteristics
• Narrowed Design: Accommodates large-radius crankshafts commonly used in performance builds

These bearings are specifically developed for performance applications that produce high loads for extended periods, making them ideal for turbocharged Subaru engines running elevated boost levels, high RPM operation, and endurance racing. The SecureBond adhesion process ensures superior layer stability, critical for preventing bearing failure under extreme stress.

Standard size bearing set designed for engines with unworn or freshly machined crankshafts to factory specifications.