ACL Race Connecting Rod Bearings 4B1972H – Honda K20 / K24 / K20C1

Complete set of ACL Race Series high-performance connecting rod bearings with manufacturer’s part number 4B1972H. Designed for Honda’s K-series and K20C1 Type-R engines, these bearings are engineered for strength, precision, and endurance. The tri-metal construction ensures excellent wear resistance, improved oil film retention, and stable pressure at high RPMs, making them perfect for tuned and racing applications.

Main Features:

• High-strength ACL Race Series design – ideal for performance and motorsport use
• Stable oil pressure under extreme loads
• Tri-metal material structure with superior fatigue resistance
• Precision fit for OEM and forged crankshafts
• Suitable for turbocharged and high-output engines

Technical Specifications:

• Shaft journal diameter: 47.980 – 48.000 mm
• Housing bore diameter: 51.004 – 51.024 mm
• Bearing wall thickness: 1.500 mm
• Bearing length: 15.40 mm
• HX version (extra clearance): 1.487 mm

Applications:

• Honda Civic Type-R 2002–2005 – K20A2
• Honda Civic Type-R 2006–2011 – K20Z2
• Honda Civic Type-R 2015–2025 – K20C1
• Honda Accord 4D 2003–2015 – K24A3, K24Z3
• Honda Accord Tourer 2002–2015 – K24A3, K24Z3

OEM Reference Numbers:

13211-PRB-A01, 13212-PRB-A01, 13213-PRB-A01, 13214-PRB-A01, 13215-PRB-A01, 13216-PRB-A01, 13217-PRB-A01,
13211-RBB-003, 13212-RBB-003, 13213-RBB-003, 13214-RBB-003, 13215-RBB-003, 13216-RBB-003, 13217-RBB-003,
13211-RBB-004, 13212-RBB-004, 13213-RBB-004, 13214-RBB-004, 13215-RBB-004, 13216-RBB-004,
13211-RL6-G01, 13212-RL6-G01, 13213-RL6-G01, 13214-RL6-G01, 13215-RL6-G01, 13216-RL6-G01, 13217-RL6-G01,
13211-5A2-A01, 13212-5A2-A01, 13213-5A2-A01, 13214-5A2-A01, 13215-5A2-A01, 13216-5A2-A01, 13217-5A2-A01, 13218-5A2-A01

Why Choose ACL Race Bearings 4B1972H?

• Manufactured by ACL Australia – trusted worldwide in motorsport and engine building
• Exceptional fatigue strength and load capacity
• Perfect fitment for Honda K20 / K24 / K20C1 engines
• Recommended for turbo, supercharged, and high-RPM engines

FAQ – Frequently Asked Questions

Q: Are ACL 4B1972H bearings compatible with the K20C1 (Civic Type-R)?
A: Yes, ACL confirms full compatibility with the K20C1 engine.

Q: What’s the difference between 4B1972H and 4B1972HX?
A: The HX version provides approximately +0.025 mm (0.001”) of extra oil clearance, ideal for high-power and high-temperature setups.

Q: Can these bearings be used with forged crankshafts?
A: Yes. ACL Race Series bearings are designed to fit both OEM and forged cranks with a nominal 48 mm journal diameter.

Q: Is this a complete set for the entire engine?
A: Yes, this is a full set of connecting rod bearings for all cylinders.

Also check out the ACL Race Main Bearings 5M1959H – perfect match for K20 and K24 engines.