ACL Race Series HX Standard-Size Rod Bearings for Honda/Acura K20 & K24

The ACL Race Series HX Connecting Rod Bearing Set is designed for compatible Honda and Acura K-series engines using standard-size crankshaft rod journals but requiring additional oil clearance. The HX configuration provides approximately 0.001 inch (0.025 mm) more oil clearance than ACL’s standard-clearance version.

This complete four-cylinder set contains eight bearing shells for the four connecting rods. ACL Race Series bearings use high-performance tri-metal construction and design features intended to support demanding street, racing and high-RPM engine applications.

Important: The “STD” designation refers to the standard crankshaft journal size. These are HX extra-clearance bearings and do not provide standard oil clearance. Measure every crankshaft journal, connecting-rod bore and assembled bearing clearance before installation.

Features

• ACL Race Series connecting-rod bearing set
• HX extra-clearance configuration
• Provides approximately 0.001 inch or 0.025 mm additional oil clearance
• Designed for standard-size crankshaft rod journals
• High-performance tri-metal bearing construction
• High-strength overlay with reduced thickness for improved fatigue resistance
• Hardened steel backing supports the bearing lining and retention
• Increased crush helps improve bearing retention in the connecting rod
• Unplated bearing backs promote heat transfer and housing grip
• Increased eccentricity helps accommodate bore distortion at high engine speeds
• Consistent wall tolerances support accurate bearing-clearance setup
• Includes eight bearing shells for four connecting rods
• ACL part number 4B1972HX-STD

Engine Fitment

Known applications include compatible versions of the following Honda and Acura K-series engines:

• K20A2
• K20Z1
• K20Z3
• K23A1
• K24A1
• K24A2
• K24A4
• K24A8
• K24Z1
• K24Z3
• K24Z7

Fitment note: Engine-bearing selection must be based on the exact engine code and measured internal dimensions. Vehicle year, model and engine displacement alone are not sufficient to confirm fitment.

These bearings are manufactured for standard-size crankshaft journals while providing additional assembled oil clearance. They are not an undersize bearing set for a reground crankshaft.

What’s Included

• 8 ACL Race Series HX connecting-rod bearing shells
• Enough bearing shells for 4 connecting rods

Connecting rods, rod bolts, crankshaft, main bearings, thrust washers, assembly lubricant and other engine components are not included.

Installation

Measure each crankshaft rod journal and connecting-rod housing bore using calibrated precision equipment. Install the bearing shells in clean, properly prepared connecting rods and verify the assembled oil clearance for every journal.

Follow the connecting-rod and fastener manufacturer’s procedures for lubrication, tightening sequence, stretch or torque specifications. Confirm bearing clearance using appropriate professional measuring methods before final engine assembly.

Professional installation by an experienced engine builder is strongly recommended. Do not select these bearings solely from the engine code or the “STD” marking.