ACL Race Series Rod Bearings 4B1925H-STD – Honda B18C4 / B18C6

ACL Race Series 4B1925H-STD high-performance connecting rod bearings are designed for Honda’s legendary B18C engines. Featuring tri-metal construction (steel / copper-lead / babbitt) and race-grade precision, they deliver excellent oil film stability and load capacity under extreme RPM and temperature. A proven choice for both naturally aspirated and forced-induction builds.

Applications and specifications

• Manufacturer part number: 4B1925H-STD (standard size)
• Engine codes: Honda B18C4, B18C6
• Vehicle applications: Civic 5D MB6 (B18C4), Civic Aerodeck MC2 (B18C4), Integra DC2 Type-R (B18C6)
• Shaft diameter: 44.976 – 45.000 mm
• Tunnel diameter: 48.000 – 48.024 mm
• Maximum wall thickness: 1.502 mm
• Maximum bearing width: 17.5 mm

Replaces OEM Honda part numbers:
13211-P72-003, 13212-P72-003, 13213-P72-003, 13214-P72-003, 13215-P72-003, 13216-P72-003, 13217-P72-003

Features and advantages of ACL Race Series

• Tri-metal structure – superior fatigue resistance thanks to copper-lead intermediate layer and precision-bonded steel backing.
• High-RPM stability – maintains a consistent oil film under elevated pressure and temperature.
• Racing-grade tolerances – micron-level precision enables optimal oil clearance for performance builds.
• Load endurance – ideal for turbocharged, supercharged or high-compression engines.
• Excellent anti-scuff protection – optimized surface finish prevents bearing wipe or cold-start damage.

ACL Race 4B1925H-STD bearings are trusted by professional engine builders worldwide. They’re a top choice for B-series Honda engines used in street-legal track builds and endurance racing applications.

FAQ – Frequently Asked Questions about ACL Race 4B1925H-STD

1. Are these bearings suitable for B16 engines?
No. The 4B1925H-STD set is designed specifically for B18C4 and B18C6 engines. B16 engines require different ACL part numbers due to smaller crankpin diameters.

2. Are these standard-size bearings?
Yes. The “STD” specification means factory-size (nominal) bearings, for use with unground OEM crankshafts. Undersize variants are available for reground cranks.

3. Can they be used in turbo or racing applications?
Absolutely. ACL Race bearings are engineered for heavy-duty use and withstand high cylinder pressures typical in turbocharged and track engines.

4. What is the recommended oil pressure range?
In practice, Honda B-series engines maintain approx. 4.0–5.5 bar (60–80 psi) at 6000 rpm for stable oil film pressure, depending on clearance and oil viscosity.

5. Do they require a break-in period?
Not a conventional one – however, engine builders typically perform a 20–30 minute initial run using a mineral 10W-30 oil to seat the bearings and establish the oil film before switching to full synthetic oil.