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R18A Engine Review

R18A Engine

The 1.8 liter R18A engine was presented in 2006 for the Honda Civic. This new R-series was created to replace the old D-series engines. The R18 is a replacement for the D17 engine.

It has an aluminum cylinder block and 16 valve SOHC aluminum cylinder head. The aluminum pistons are cooled with oil by piston cooling jets installed in the block. The engine got a timing chain instead of a belt as on previous D-series engines. The R18 hasn't hydraulic tappets (checking and adjusting valves are every 25,000 miles or 40,000 km). The valve clearance for intake valves is 0.18-0.22mm, exhaust - 0.23-0.27 mm. The engine already has the variable valve timing Honda's i-VTEC system. There is a plastic variable length intake manifold also.

The engine was reduced in displacement for larger Honda's model such Accord. This 2.0 liter version is R20A engine.

Engine Specs

Honda Motor Company
2006-present day
Cylinder Block Material
Fuel system
Fuel injection
Number of cylinders
Valves per cylinder
Stroke, mm
87.3 (3.44 in)
Bore, mm
81.0 (3.19 in)
Compression Ratio
Displacement, cc
Power, hp
140-141 (103-104kW) / 6300
Torque, lb ft
128 (174 Nm) / 4300
Engine weight
223 lbs, 101 kg
Engine oil viscosity
0W-20, 0W-30, 5W-20, 5W-30
Engine oil capacity, liter
Oil change interval, mile
6,000 (10,000 km) or 12 month
Oil consumption per 1000 miles as normal
Up to 1000 ml
Honda Civic, Honda Cossroad, Honda Stream, Honda FR-V

R18 Engine Problems and Reliability

1. The engine knock. Usually, this sound is made by a canister purge valve, this is normal. Also If the adjusting of the valves clearances was long ago, possible the time has come.
2. Some noise is produced by the drive belt tensioner. Its life is 60,000 miles (100,000 km).
3. Vibrations. If an engine is cold, that is ok. But if vibration continues all time, check the left engine mount.
It is important to use the recommended engine oil. This will keep the VTEC system in good condition for a long time. The engine life of R18 is about 180,000 miles (300,000 km).


1. R18A1 - version of the engine for the Japanese and North American market. 10.5 compression ratio, 141 hp, 128 ft lb (174Nm).
2. R18A2 - European version. 10.5 compression ratio, 140 hp, 128 ft lb (174Nm). Produced since 2012.
3. R18Z1 - version for Southeast Asian 2012+ Civic model. 10.6 compression ratio, 141 hp, 128 ft lb (174Nm).

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