ACL Race Series Rod Bearings – Honda Civic Type R (FK8/FL5) – K20C1

Overview

The ACL Race Series Conrod Bearings (Part Nos: 4B1972H-STD, 4B1972HX-STD, 4B1972H-.25) are built for high-performance and motorsport engine applications. Engineered with ACL’s proven tri-metal construction, these bearings offer superior oil film control, fatigue resistance, and stability under high-RPM and high-load conditions. Whether you're building a street-driven turbo K20C1 or a competition-spec K24, ACL bearings are trusted by top engine builders worldwide.

Key Features

• High-strength tri-metal bearing construction for increased durability
• Hardened steel backing enhances structural integrity and bearing shell support
• Reduced overlay thickness improves fatigue strength at high RPM
• Tight wall tolerances ensure consistent oil clearances across all cylinders
• No flash plating on the reverse side for better heat transfer and housing grip
• Enhanced crush for optimal retention inside the connecting rod housing
• Chamfered edges accommodate high-performance crankshaft fillets

Available Sizes

Technical Specifications

• Tunnel Diameter: 51.004 – 51.024mm
• Shaft Diameter: 47.980 – 48.000mm
• Maximum Wall Thickness: 1.5mm
• Maximum Bearing Length: 15.4mm
• Configuration: Identical Halves
• Weight: Approx. 120g

Vehicle Compatibility

Suitable for performance builds using Honda K20C1 and K24 engines. Confirm sizing with crankshaft and rod specs before installation.