The Honda C25A2 is a 2,493 cc, 60 — degree V6 naturally aspirated petrol engine produced between 1993 and 1998. It features a single overhead camshaft (SOHC) per bank, 24 — valve design with Honda's PGM — FI electronic fuel injection, delivering smooth, linear power and refined operation. Variable Valve Timing and Lift Electronic Control (VTEC), engaging at 4,800 rpm, provides a noticeable surge in power for overtaking and highway merging.
Fitted primarily to the fourth —…
Honda
Production years 1993–1998 meet applicable US Federal and Japanese Tier 1 emissions standards (Honda Emissions Doc. US-FED-93).
The Honda C25A2 is a 2,493 cc V6 naturally aspirated petrol engine engineered for luxury sedans (1993-1998). It combines SOHC valvetrain with VTEC and PGM-FI to deliver smooth, refined power with a sporty top-end character. Designed to meet contemporary US Federal and Japanese Tier 1 standards, it balances luxury comfort with responsive performance.
| Parameter | Value | Source |
|---|---|---|
Displacement | 2,493 cc | |
Fuel type | Petrol (Gasoline) | |
Configuration | V6, SOHC, 24‑valve, VTEC | |
Aspiration | Naturally Aspirated | |
Bore × stroke | 86.0 mm × 71.5 mm | |
Power output | 134 kW (182 PS) @ 5,500 rpm | |
Torque | 230 Nm @ 4,500 rpm | |
Fuel system | PGM-FI (Programmed Fuel Injection) | |
Emissions standard | US Federal / Japanese Tier 1 | |
Compression ratio | 9.6:1 | |
Cooling system | Water‑cooled | |
Turbocharger | None | |
Timing system | Belt-driven | |
Oil type | Refer to vehicle handbook / manufacturer specification | |
Dry weight | Approx. 162 kg |
The Honda C25A2 was developed for Honda's flagship Legend (4th Gen) and its Acura RL counterpart with longitudinal mounting. This engine featured specific calibrations for the Legend/RL's chassis and drivetrain and was not shared with other contemporary Honda models. All applications are documented in OEM technical bulletins.
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Field reports and technical service bulletins highlight component wear patterns under high-load operation. Adherence to manufacturer service intervals and approved fluid specifications is critical for long-term reliability.
Analysis derived from Honda technical bulletins (1993-1998) and preliminary NHTSA owner complaint data (archived). Repair procedures should follow manufacturer guidelines.
The most common questions about engine codes, what they mean, how to find them and how this database works
The C25A2 is generally very reliable if meticulously maintained. Its primary risk is the timing belt; failure is catastrophic. With timely belt changes, addressing rear main seal leaks, and general upkeep, these engines can easily surpass 250,000 miles. Neglect, however, leads to expensive repairs.
The most critical issue is timing belt failure. Other common problems include rear main seal leaks, valve cover gasket leaks, and water pump failures. These are well-documented in Honda service bulletins and are largely age-related wear items.
The C25A2 was used in the fourth-generation Honda Legend (KA9) from 1993 to 1998 and its North American counterpart, the first-generation Acura RL (KA9), from 1996 to 1998. It was the sole V6 engine for these models during this period.
Yes, but gains are modest. The C25A2 responds well to basic bolt-ons like a performance exhaust and cold air intake. More significant power increases require internal modifications or a swap to a more potent C-series engine like the C32B. ECU tuning options are limited for this era.
For a 2.5L V6 luxury sedan of its era, it was reasonable. Expect around 11.2 L/100km city and 8.1 L/100km highway, or approximately 21-25 mpg (US combined) in a Legend/RL. Real-world figures vary, but it prioritized smooth power over ultimate efficiency.
Yes, absolutely. This is the single most important fact about this engine. If the timing belt breaks or jumps, the pistons will collide with the open valves, causing severe and expensive internal damage. Replacing the belt on schedule is non-negotiable.
Honda originally specified 5W-30 or 10W-30 viscosity oil. A high-quality conventional or synthetic blend meeting API SG/SH (or newer) specifications is suitable. Modern 5W-30 synthetic is an excellent choice for easier cold starts and better overall protection.
Comprehensive technical documentation and regulatory references
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Regulatory Stability
EU regulations are referenced using CELEX identifiers for long-term stability.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
Type-approval guidance and documentation.
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