King Engine Bearings MB5527XP STDX XP Series Tri-Metal Performance Main Bearing Set

The King Engine Bearings MB5527XP STDX is an XP Series tri-metal performance crankshaft main bearing set engineered for Toyota 4AGE, 4AGZE, and 16V 1.6L engines. Designed for builders who demand maximum load capacity and reliability under sustained high-RPM conditions, the XP Series combines advanced metallurgical construction with precision geometric design to outperform conventional race bearings.

pMaxBlack™ Tri-Metal Construction

At the core of the XP Series is King's proprietary pMaxBlack™ overlay technology. Unlike standard high-performance overlays that use 2–3% copper content and achieve load ratings of 8,000–8,500 PSI, King's pMaxBlack™ overlay features 5% copper content combined with an innovative nano-scaled hardening process — resulting in significantly higher load capacity and fatigue resistance. The enhanced intermediate layer increases tin content to 4.5% (versus the typical 2–3%), making it 22% harder at 115 HV with a load carrying capacity of 17,000 PSI.

XP Series Features:

• pMaxBlack™ Overlay — Nano-scaled hardening process produces superior load capacity up to 10,200 PSI; 24% harder than conventional tri-metal race bearings
• Bull's Eye Tolerance — Industry-leading wall tolerances with all shells matched to 0.0001"
• Half-Groove Main Bearings — Upper shells are grooved while lower shells remain full-width for uncompromised load capacity
• Enlarged, Chamfered Oil Holes — Improved oiling with a 90° oil groove shape that maintains oil flow and expands surface area for greater load capacity
• Medium Eccentricity — Optimizes load distribution and promotes consistent lubrication across the bearing surface
• Narrowed Design — Mains are narrowed to accommodate large-radius crankshafts
• SecureBond Adhesion — Proprietary bonding process ensures superior stability between the top and intermediate bearing layers
• 15%–30% Greater Load Capacity — Over traditional tri-metal bearings for demanding performance applications

Ideal Applications:

• Circle track racing
• Drag racing
• Off-road and off-shore competition
• Any high-load, long-duration application using forged steel aftermarket crankshafts

King Engine Bearings offers the widest selection of sizes in the industry, including special clearance options. The MB5527XP is available in standard (STDX) and multiple oversizes to meet your exact build specifications.