The Honda R18A2 is a 1,799 cc, inline‑four naturally aspirated petrol engine produced between 2006 and 2012. It features port fuel injection, single overhead camshafts (SOHC), and i-VTEC variable valve timing. In standard applications, it delivers 103 kW (140 PS) and 174 Nm of torque, with i-VTEC enabling a broad, efficient power band for relaxed cruising.
Fitted primarily to the eighth-generation Honda Civic (FA/FG) sedan and coupe, the R18A2 was engineered for fuel efficiency, low emissions, and smooth daily driving. Emissions compliance was achieved through precise fuel metering and a close-coupled catalytic converter, meeting Euro 4 standards from launch.
One documented service consideration is potential for excessive oil consumption in high-mileage engines, noted in Honda Service Bulletin A10-033. This is typically attributed to wear of piston rings and was addressed in later production with revised ring design and material.
Honda
Production years 2006–2012 meet Euro 4 standards across all applicable markets (EU Regulation (EC) No 715/2007).
The Honda R18A2 is a 1,799 cc inline‑four naturally aspirated petrol engineered for compact sedans (2006-2012). It combines port fuel injection with SOHC i-VTEC to deliver smooth, predictable power and excellent fuel economy. Designed to meet Euro 4 standards, it prioritizes efficiency and low running costs.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 1,799 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑4, SOHC, 16‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 81.0 mm × 87.3 mm | |
| Power output | 103 kW (140 PS) @ 6,300 rpm | |
| Torque | 174 Nm @ 4,300 rpm | |
| Fuel system | Port Fuel Injection (PFI) | |
| Emissions standard | Euro 4 | |
| Compression ratio | 10.6:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain-driven | |
| Oil type | Honda 5W-20 (or 5W-30) | |
| Dry weight | 120 kg |
The SOHC i-VTEC design offers smooth, linear power ideal for commuting but lacks the high-RPM excitement of DOHC engines. The port injection system is inherently resistant to intake valve carbon buildup. Using the specified 5W-20 oil ensures optimal fuel economy and chain longevity. High-mileage engines should be monitored for oil consumption per Honda SIB A10-033, as worn piston rings are a known wear item.
Oil Specs: Requires Honda 5W-20 specification for optimal fuel economy (Honda Owner's Manual). 5W-30 is an acceptable alternative.
Emissions: Euro 4 certification applies to all 2006–2012 models (EU Regulation (EC) No 715/2007). No market-specific variations.
Power Ratings: Measured under SAE J1349 standards. Peak output requires 95 RON fuel (Honda TIS Doc. R18A2-PERF).
Honda Technical Information System (TIS): Docs R18A2-SPEC, R18A2-PERF
EU Regulation (EC) No 715/2007
Honda Service Information Bulletin (SIB) A10-033
SAE International: J1349 Engine Power Certification Standards
The Honda R18A2 was used across Honda's FA/FG platform with transverse mounting and was exclusive to Honda. This engine received platform-specific adaptations-reinforced engine mounts in the Civic Si (though not used in Si) and different intake manifolds for Sedan vs Coupe-and all variants share the same core architecture. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, near the alternator (Honda TIS R18A2-ID). The 8th VIN digit for R18A2-equipped vehicles is typically 'R'. The engine can be visually identified by its silver plastic valve cover with "i-VTEC" branding and the absence of a turbocharger. Critical differentiation from the K20: The R18A2 has a SOHC design and lower power output. Service parts, including piston rings, were revised in 2009; pre-2009 parts may not be compatible with later engines (Honda SIB A10-033).
The R18A2's primary reliability consideration is oil consumption in high-mileage engines, with elevated incidence in vehicles with over 150,000 km. Honda service data indicates this is often due to normal wear, while owner reports frequently cite minor VTEC solenoid issues. Consistent use of correct oil and adherence to service intervals mitigates most long-term concerns.
Analysis derived from Honda technical bulletins (2006-2012) and aggregated owner-reported data (2008-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA R18A2.
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