King Engine Bearings MB5220XP05 XP Series Tri-Metal Main Bearing Set Subaru EJ20 EJ22 EJ25 0.5mm Undersize

The King Engine Bearings MB5220XP05 is a XP Series tri-metal performance main bearing set engineered for Subaru WRX/STI EJ20, EJ22, and EJ25 boxer engines. Featuring the proprietary pMax Black™ tri-metal construction, this set is purpose-built for high-load, long-duration racing applications using forged steel aftermarket crankshafts. This listing is for the 0.5mm (0.020") undersize variant. The thrust flange is located at the #3 position, matching the factory Subaru EJ-series crankshaft specification.

XP Series pMax Black™ Construction:

• Enhanced tri-metal copper-lead construction with nickel barrier layer and SecureBond™ adhesion process for superior stability between layers
• pMax Black™ overlay — a 0.0005" metallurgically enhanced and hardened performance overlay that delivers 24% greater hardness than conventional tri-metal race bearings
• 15%–30% greater load capacity than standard tri-metal bearings, ideal for sustained high-RPM and high-boost applications
• Mains are half-grooved to preserve full load capacity in the lower shell

King XP Geometric Features:

• Bull's Eye Tolerance® — all shells matched to ±0.0001" wall thickness for the tightest tolerances in the industry
• Enlarged, chamfered oil holes on mains for improved oiling and reduced risk of oil starvation
• Medium eccentricity design for optimum load distribution and oil film development
• Narrowed bearing width to clear large-radius crankshaft fillets without fillet ride
• Optimized crush height for secure shell seating and reduced spin potential at high RPM

Applications:

• High-load, long-duration racing: circle track, off-road, off-shore, and other applications requiring forged steel crankshafts
• High-boost street performance builds on Subaru EJ-series engines
• Engines requiring a 0.5mm (0.020") undersize main bearing due to a reground crankshaft

Set Contents: 5 pairs of main bearing shells (upper and lower), including the flanged thrust bearing at position #3.

King Engine Bearings has been manufacturing precision engine bearings since 1960. All XP series bearings are produced at King's AS9100 aerospace-certified production facility, ensuring consistent quality for the most demanding performance applications.