King Engine Bearings MB5220XP025 XP Series Tri-Metal Main Bearing Set

The King Engine Bearings MB5220XP025 is a XP Series high-performance main bearing set engineered for Subaru EJ20, EJ22, and EJ25 engines. Designed specifically for performance and racing applications using forged steel aftermarket crankshafts, this bearing set delivers the load capacity and durability required for high-output, high-RPM builds.

The XP Series features King's exclusive pMax Black tri-metal construction — a copper-lead bearing structure with a nickel barrier, SecureBond adhesion layer, and a 0.0005" metallurgically enhanced performance overlay. This unique composition is 24% harder than conventional tri-metal race bearings, delivering superior resistance to surface fatigue under extreme and sustained loads.

Key Features:

• pMax Black Tri-Metal Construction — Enhanced copper-lead structure with nickel barrier for superior durability and load resistance
• SecureBond Adhesion Process — Provides exceptional stability between the top and intermediate layers, preventing delamination under stress
• 15%–30% Greater Load Capacity — Outperforms traditional bearings in high-load, long-duration racing environments
• Bull's Eye Tolerance — All shells matched to 0.0001" wall tolerance, the tightest in the industry
• Hardened Performance Overlay — 0.0005" overlay withstands greater loads and resists surface fatigue better than standard bearings
• Half-Grooved Mains — Upper shells are ½ grooved to preserve full load capacity in the lower shell
• Enlarged, Chamfered Oil Holes — Improves oiling performance to bearing surfaces under high RPM
• Medium Eccentricity Design — Enables optimum load distribution and consistent oil film throughout the bearing surface
• Narrowed Design — Compatible with large-radius crankshafts common in performance forged cranks
• +0.025mm Oversized — Designed for use with journals that have been machined 0.025mm undersize

Ideal Applications:

• High-load, long-duration racing including circuit, off-road, and off-shore competition
• High-performance street and track builds using forged steel aftermarket crankshafts
• Subaru EJ20, EJ22, and EJ25 performance engine builds requiring precision-tolerance bearings

King Engine Bearings offers the industry's widest selection of sizes and clearance options, ensuring the right fit for even the most demanding engine builds. The MB5220XP025 is part of a complete range of XP Series performance bearings built to survive where standard bearings fail.