ACL 4B1906H-STD Race Rod Bearing Set Standard Honda K20A3 F23A Civic RSX Accord

Vehicle Fitment

• 2002-2006 Acura RSX Base (K20A3, 2.0L DOHC 16v i-VTEC)
• 2002-2005 Honda Civic Si / EP3 (K20A3, 2.0L DOHC 16v i-VTEC)
• 1998-2002 Honda Accord - DX, LX, EX (F23A1/A4/A5/A7, 2.3L SOHC 16v VTEC)
• 1998-1999 Acura CL 2.3 (F23A1, 2.3L SOHC 16v VTEC)
• 1998 Honda Odyssey (F23A, 2.3L SOHC VTEC)
• 1999 Isuzu Oasis (F23A, 2.3L SOHC VTEC)
• Various Euro-market Honda Accord, CR-V, FR-V, Prelude with K20A3 or F23A/F23Z engine codes

Fitment Notes

• The Honda K20A3 (1998cc) and F23A/F23Z series (2254cc) share identical crankshaft rod journal dimensions, allowing a single bearing set to serve both engine families at standard crankshaft size.
• Standard (STD) crankshaft rod journal diameter - for use with stock or unworn crankpins at factory diameter only. For reground crankshafts, use 4B1906H-.025 (+0.025mm), 4B1906H-.25 (+0.25mm), or 4B1906H-.50 (+0.50mm) as appropriate.
• An HX extra-clearance variant (4B1906HX-STD) is also available for builders targeting approximately 0.025mm (0.001") additional running clearance at standard journal diameter.
• Note: The higher-performance K20A2 and K20Z1 engines use a different bearing set (4B1972H) with larger crankpin journals. Verify your specific engine code before ordering.
• Always measure crankshaft rod journal diameter with a micrometer before selecting bearing size. Confirm actual clearance with Plastigage or a dial bore gauge after assembly.
• Sold as a complete set of 8 bearing shells - sufficient for one full 4-cylinder engine build.

Features

• Tri-metal construction: copper-lead alloy lining bonded over a hardened steel backing, with a high-strength overlay plate - engineered for the high-revving, VTEC-enabled demands of built K20 and F-series Honda engines.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under high sustained loads.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - important in high-RPM naturally aspirated builds and forced-induction K20A3 applications.
• Increased bearing crush and tighter wall tolerances ensure consistent, secure seating in the connecting rod housing bore, reducing the risk of bearing spin.
• Enlarged ID chamfers on bearing edges accommodate the larger fillet radii found on performance and aftermarket Honda crankshafts.
• 3/4-groove design optimizes oil supply to the rod journal and maximizes load-carrying surface area across the bearing face.
• Elimination of flash plating on bearing backs improves heat transfer and maximizes grip between the bearing shell and the rod housing bore.
• Increased eccentricity compensates for bore distortion at high RPM and assists in the formation of a stable hydrodynamic oil film under load.

Specifications

• Part Number: 4B1906H-STD
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings
• Engine Compatibility: Honda K20A3 (1998cc DOHC 16v i-VTEC); Honda F23A1, F23A4, F23A5, F23A7, F23Z2, F23Z4 (2254cc SOHC 16v VTEC)
• Crankshaft Size: Standard (STD - Unground)
• Shaft (Crankpin) Diameter: 44.976-45.001mm (1.7707-1.7717 in)
• Tunnel (Housing Bore): 48.006-48.017mm (1.8899-1.8904 in)
• Maximum Wall Thickness at Crown: 1.502mm (0.0591 in)
• Maximum Overall Length: 15.50mm (0.610 in)
• Bearing Material: Tri-Metal Copper-Lead Alloy / Hardened Steel Backing
• Quantity: Set of 8 Shells (complete engine set)

Included Components

• 8x Race Series Connecting Rod Bearing Shells - Standard Size

Product Description

The ACL Race Series 4B1906H-STD connecting rod bearing set is the standard-size performance replacement for the Honda K20A3 and F23A/F23Z engine families - covering the 2.0L DOHC K20A3 found in the Acura RSX Base and Honda Civic Si EP3, and the 2.3L SOHC F23 family found in the 6th-generation Honda Accord and related Acura CL. Despite the difference in displacement and valvetrain configuration, both engine families share identical crankshaft rod journal dimensions, making this a single versatile set for both platforms at standard crankshaft size.

Built on ACL's Race Series tri-metal platform, these bearings deliver superior fatigue resistance, bearing retention, and oil film stability compared to OEM Honda shells - a reliable upgrade for any K20A3 or F-series engine rebuild, from mild refreshes to high-RPM naturally aspirated or forced-induction builds. For the performance-focused K20A2 and K20Z1 engines (RSX Type-S, Civic Si Mk7), use the 4B1972H set instead. Always confirm clearances at assembly. Sold as a complete set of 8 shells for one engine.