King Engine Bearings MB5803XP0.25 Performance Main Bearing Set Oversize BMW - 0.25mm S65B40A

The King Engine Bearings MB5803XP0.25 is a high-performance main bearing set designed for BMW S65B40A engines found in 2008-2013 M3 models. This race-proven bearing set is engineered with 0.25mm oversize dimensions for engines that have had their crankshaft journals machined or require additional clearance.

XP Series pMaxBlack Technology:

• Tri-metal lead bronze construction with proprietary pMaxBlack overlay featuring 5% copper content
• Nano-scaled hardening process creates a fatigue-resistant black shield for superior durability
• Maximum load capacity of 10,200 PSI—24% higher than conventional performance bearings
• Overlay hardness of 18.1 HV, 29% harder than standard performance overlays
• Ideal for circle track, drag racing, and high-performance street applications with steel crankshafts

Advanced Design Features:

• Narrowed bearing width optimized for large radii crankshafts
• 90-degree oil groove shape maintains oil flow and increases bearing load capacity
• Enlarged, chamfered oil holes for improved lubrication
• Optimized crush height and eccentricity values through elasto-hydrodynamic analysis
• Industry-leading wall thickness tolerance for consistent performance shell-to-shell

King Engine Bearings has specialized exclusively in bearing manufacturing since 1960, producing all bearings in-house with rigorous quality control at every production checkpoint. The XP Series represents the pinnacle of performance bearing technology for high-load racing and performance engines.