ACL 4B1912H-.25 Race Rod Bearing Set +0.25mm Honda F20C F22C H22A S2000 Prelude

Vehicle Fitment

• 2000-2005 Honda S2000 AP1 (F20C1/F20C2, 2.0L DOHC 16v VTEC, 237-247 hp)
• 2004-2009 Honda S2000 AP2 (F22C1, 2.2L DOHC 16v VTEC, 239 hp)
• 1991-1996 Honda Prelude IV (BB1/BB3/BB4) - H22A1, H22A2 (2.2L DOHC 16v VTEC)
• 1997-2001 Honda Prelude V (BB5/BB6/BB7/BB8) - H22A2, H22A4, H22A5, H22A8, H22Z1 (2.2L DOHC 16v VTEC)
• 1997-2002 Honda Accord VI Type-R - H22A7 (2.2L DOHC 16v VTEC)

Fitment Notes

• The .25 suffix designates this as the +0.25mm oversize bearing set - intended for use when the crankshaft rod journals have been ground 0.25mm undersize during a rebuild. The thicker wall restores correct running oil clearance on a more significantly reground crankshaft.
• Do NOT use on a stock, unground crankshaft. For standard journal diameter, use 4B1912H-STD. For crankpins ground 0.025mm undersize, use 4B1912H-.025.
• 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.
• The F20C/F22C and H22A/H22Z engine families share identical crankpin journal dimensions - a single bearing set fits all variants listed above at the same oversize.
• 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 extreme high-RPM demands of the F20C (9,000 rpm redline) and H22A VTEC engines.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under the sustained high-RPM loads characteristic of naturally aspirated Honda performance engines.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - critical in high-revving S2000 and Prelude builds at or above the factory power ceiling.
• 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: 4B1912H-.25
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings
• Engine Compatibility: Honda F20C1, F20C2 (1997cc); Honda F22C1 (2157cc); Honda H22A1, H22A2, H22A4, H22A5, H22A7, H22A8, H22Z1 (2157cc)
• Crankshaft Size: +0.25mm Oversize (for crankpins ground 0.25mm undersize)
• Shaft (Crankpin) Diameter: 47.980-48.000mm (1.8890-1.8898 in)
• Tunnel (Housing Bore): 51.004-51.024mm (2.0080-2.0088 in)
• Maximum Wall Thickness at Crown: 1.496mm (0.0589 in)
• Maximum Overall Length: 19.4mm (0.764 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 - +0.25mm Oversize

Product Description

The ACL Race Series 4B1912H-.25 connecting rod bearing set is the +0.25mm oversize option for the Honda F20C, F22C, and H22A/H22Z DOHC VTEC inline-4 engine family - covering the legendary Honda S2000 AP1 and AP2 (2000-2009), the Honda Prelude IV and V (1991-2001), and the Accord Type-R. The F20C and F22C engines are particularly known for their extreme rev ceiling (9,000+ rpm in F20C form), making bearing quality a critical consideration in any rebuild. This oversize set is selected when the crankshaft rod journals have been ground 0.25mm undersize to address wear or scoring, restoring correct oil clearance on the reground crank.

The F20C/F22C and H22A/H22Z families share identical crankpin journal dimensions, allowing this single set to serve all listed applications at the +0.25mm oversize. 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. Always verify crankshaft journal diameter with precision measurement and confirm clearances at assembly before final torque. Sold as a complete set of 8 shells for one engine.