ACL 7M1397HX-STD Main Bearing Set, Extra Clearance for BMW N54B30 / N55B30 / S55B30

Description ACL 7M1397HX-STD Main Bearing Set, Extra Clearance for BMW N54B30 / N55B30 / S55B30

ACL Race Series Trimetal Engine Bearings are engineered to meet the demands of high-performance and high-RPM engine operation. Through a precise combination of advanced design, metallurgy, and manufacturing processes, these bearings deliver the durability, stability, and consistency expected in performance and motorsport applications.

Designed for increased engine speeds and load conditions, ACL Race Series bearings are available for a wide range of popular 4-, 6-, and 8-cylinder engines. The construction focuses on improved fatigue resistance, enhanced bearing retention, optimized oil control, and consistent clearances, making them suitable for performance street and competition use.

• High-strength overlay plate with reduced thickness for improved fatigue resistance
• Hardened steel backs on all connecting rod bearings for enhanced support and retention
• Increased bearing crush for improved housing retention
• Elimination of flash plating on bearing backs to improve heat transfer and housing grip
• Increased eccentricity to compensate for bore distortion and support hydrodynamic oil film formation at high RPM
• 3/4-grooved main bearings to optimize load capacity and oil flow to connecting rod bearings
• Tight and consistent wall tolerances for stable bearing clearances
• Enlarged inner diameter chamfers to accommodate large fillet radius performance crankshafts