Product Attributes

Product Details

Product Overview

The 31100-P3F-J51 is a Honda OE-spec replacement alternator delivering 12V 80A output with a 4-rib (4PK) pulley, engineered for Honda Civic B18C4 and Honda Integra B18C performance petrol engines. This Hitachi-pattern aftermarket unit matches the original charging-system specification for these popular JDM performance platforms.

Fitted with external regulator design, this brand-new alternator is stocked in-house with a 1-year warranty and 10-day dispatch lead-time. The 80-amp rating is factory-correct for stock electrical loads of B18C4 / B18C powertrains, supporting standard lighting, climate control and factory audio equipment.

Key physical specs: net weight 4.95 kg, gross weight 5.3 kg, overall dimensions 240 x 170 x 180 mm, supplied inside neutral kraft inner carton.

The B18C Engine Platform and 80A Charging-System

The B18C-series 1.8L four-cylinder DOHC VTEC petrol engine is famous within JDM communities, deployed in the Honda Integra DC2 and Civic models with B18C4 variant. Different B18 platform variants were equipped with alternators of different amperage and pulley configurations.

It is critical to distinguish alternator hardware between base-spec and higher-option vehicles. Some market-specific B18 units may use different amp ratings or 5-rib pulleys. Those assemblies are not directly interchangeable with this 80A-4PK unit.

The 4-rib pulley matches the original accessory-belt layout for B18C4 and B18C, driving alternator, water pump and power-steering pump. Installing wrong rib-count pulley will cause belt mis-tracking, slippage, premature belt failure and charging faults. Always cross-check against your old alternator.

Technical Specifications

Engine Compatibility and Cross Reference

This alternator fits Honda vehicles equipped with B18C4 and B18C 1.8 L VTEC petrol engines. Do not rely solely on vehicle model name for fitment validation; always verify engine code, old-part OE number, pulley rib-count and amp label on your original alternator.

Multiple Honda OE numbers appear across production batches and regional market specifications for this same alternator family. If your original unit bears one of the listed cross-reference numbers, 31100-P3F-J51 serves as a direct drop-in replacement.

What to Look for in a Replacement

Follow these five verification steps before placing your order to avoid wrong-part returns:

• 1. Check the amperage label on your old alternator: confirm it is rated for 80A. Higher-amp upgraded alternators or lower-output base units cannot substitute.

• 2. Count pulley ribs: this unit requires 4PK (4-rib). Units with 5-rib pulley are incompatible for this accessory drive setup.

• 3. Confirm engine code is B18C4 or B18C. Other B-series engines (B16, B18B non-VTEC) use different alternator assemblies.

• 4. Match against OE / reference part numbers stamped on your original housing.

• 5. Weight cross-check: genuine matching replacement weighs approximately 4.95 kg net; significant weight difference indicates wrong assembly.

Application Scenarios

• Independent repair shops and JDM specialist garages: servicing popular Civic and Integra VTEC platforms across Europe, Oceania, Asia-Pacific and Latin-American markets.

• Parts counters and jobbers stocking JDM performance replacement electric parts.

• Enthusiast vehicle owners restoring / maintaining original-spec Integra DC2 and Civic B18C4.

• Used-car export traders supplying pre-owned Honda performance vehicles to global secondary markets.

• Hobbyists with lightly modified vehicles retaining factory-style electrical systems.

FAQ

Q: Can I fit this alternator onto a non-VTEC B18B engine?
A: No. B18B utilises different alternator mounting, pulley and terminal layout. Confirm engine code before ordering.

Q: My old alternator shows OE number 31100-P3F-A01, will 31100-P3F-J51 work?
A: Yes. These numbers belong to same alternator family for B18C / B18C4, differing only by production revision. It serves as direct replacement.

Q: What is the normal charging voltage after installation?
A: Running engine idle, battery terminal voltage should read 13.8V-14.5V; at 2000 rpm target stabilises around 14.0-14.7V.

Q: Can I install this unit if my car has heavy audio / auxiliary-light modifications?
A: This is stock-spec 80A alternator for factory electrical load. Heavy-draw accessories may exceed its capacity; consider high-output upgrade solution in that case.

Q: What is your warranty and lead-time?
A: Goods are in stock with 10-day dispatch lead-time. 1-year warranty applies from installation date; warranty excludes damage caused by mis-installation, wrong belt tension, or vehicle-wiring faults.

In Practice

For technicians working on Honda B-series VTEC platforms: Before removing the existing alternator, perform charging-system diagnostics. Measure battery terminal running voltage with multimeter. Weak batteries, corroded ground connections or faulty main harness can mimic alternator failure symptoms. Always disconnect battery negative terminal before commencing removal work.

Take photos of wiring connectors and bolt positions during disassembly to avoid mis-routing during reassembly. Observe correct belt tension: 10-15 mm deflection when pressing belt mid-span. Over-tightened belts accelerate alternator bearing wear; loose tension creates slipping and insufficient charging. Torque mounting bolts to Honda workshop-manual specifications.

Inexperienced home mechanics are recommended to entrust replacement work to a qualified auto-electric repair shop. Incorrect wiring risks burning alternator or vehicle-system components.

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