Honda F18A3 Specifications
| Engine Model: Honda F18A3 |
| Engine Type: 4-cycle inline 4-cylinder DOHC 16-valve liquid-cooled gasoline |
| Total Displacement: 112.8 cu.in (1.85 L) |
| Rated Engine Power: 115-118 Hp (86-88 kW) at 6300 rpm |
| Fuel System Type: Sequential multi-point fuel injection |
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The Honda F18A3 is a 1.8-liter inline-four
gasoline engine from Honda’s F-series engine family, widely used through
the 1990s in midsize sedans such as the European-market Honda Accord.
The F18A3 was engineered to deliver a balance of fuel efficiency,
durability, and smoothness, making it suitable for daily commuting and
long-distance driving.
The engine features an aluminum cylinder head, a cast-iron block, dual
overhead camshafts (DOHC), and four valves per cylinder. It uses Honda’s
Programmed Fuel Injection (PGM-FI) and a distributor-based ignition
system. The F18A3 delivers predictable low- and mid-range torque, stable
idle quality, and long-term mechanical resilience. For owners seeking a
dependable, efficient, and easy-to-maintain powerplant, the F18A3
remains a well-regarded engine even decades after production ended.
The Honda F18A3 is a four-stroke, water-cooled, inline-four gasoline
engine with a displacement of 1,849 cc (112.8 cubic inches). Bore is
85.0 mm (3.35 inches) and stroke is 81.5 mm (3.21 inches), resulting in
a slightly oversquare configuration. The compression ratio is
approximately 9.2:1 depending on market calibration.
Power output is generally rated around 115–118 horsepower (86–88 kW) at
approximately 6,300 rpm. Peak torque is approximately 160 Nm (118 lb-ft)
at around 4,900 rpm. Idle speed is typically 700 ± 50 rpm, and the
redline is set near 6,800 rpm. The firing order is 1-3-4-2.
The lower-end assembly consists of a cast-iron block with five main
bearings supporting a forged-steel crankshaft. Pistons are lightweight
aluminum alloy, paired with forged steel connecting rods. The engine
uses Honda’s DOHC configuration without VTEC, giving it predictable
operating characteristics and consistent torque delivery across the rev
range.
The cylinder block of the F18A3 is cast iron, chosen for its strength,
durability, and ability to withstand high thermal cycling over long
periods. The oversquare geometry allows good breathing characteristics
while maintaining mechanical stability. The crankshaft is housed in five
main bearings, each providing strong support and reducing torsional
vibration.
Oil passages are drilled to ensure proper lubrication of main journals,
connecting rod journals, and the valvetrain. The block includes cast-in
coolant channels to maintain stable engine temperature. The block design
also incorporates integrated mounting points for accessories such as the
alternator and power steering pump, contributing to compactness and ease
of service.
The aluminum DOHC cylinder head features four valves per cylinder,
promoting efficient airflow into and out of the combustion chambers.
Valve sizes measure:
– Intake valves: approx. 33 mm (1.30 inches)
– Exhaust valves: approx. 28 mm (1.10 inches)
Camshafts are belt-driven by a toothed timing belt. Valve actuation uses
bucket-over-shim tappets, requiring manual adjustment at regular
intervals. The combustion chamber is a pent-roof design, contributing to
efficient mixture preparation and stable ignition. The head gasket is
multi-layer steel (MLS), improving sealing integrity at operating
temperatures.
The F18A3 uses Honda’s PGM-FI sequential multi-point fuel injection.
Fuel pressure is regulated at approximately 300–350 kPa (43–51 psi). An
electric in-tank fuel pump delivers fuel to the rail, and injectors
atomize fuel precisely at each intake port.
Sensors used in the fuel system include:
– Manifold Absolute Pressure (MAP) sensor
– Throttle Position Sensor (TPS)
– Engine Coolant Temperature (ECT)
– Intake Air Temperature (IAT)
– Oxygen sensor
– Crankshaft Position Sensor (within distributor)
The throttle body includes an idle-air-control valve (IACV), allowing
the ECU to manage idle speed and cold-start operation. Recommended fuel
is unleaded gasoline with at least 91 RON (87 AKI).
The lubrication system is a full-pressure wet-sump design using a
crankshaft-driven trochoid oil pump. Oil flows through a pickup screen,
then into a replaceable full-flow spin-on filter, before reaching the
main oil galleries.
Specifications:
– Oil capacity with filter: approx. 4.0 liters (4.2 US quarts)
– Oil pressure at 3,000 rpm: 300–400 kPa (44–58 psi)
– Idle oil pressure: approx. 70–120 kPa (10–17 psi)
Recommended oil viscosity is SAE 5W-30 or 10W-30 depending on climate.
Oil change interval is generally 8,000–10,000 km (5,000–6,000 miles)
under normal use.
The cooling system is a closed-loop, forced-circulation liquid system
using a belt-driven centrifugal water pump. Coolant circulates through
the block, head, heater core, and aluminum radiator.
Cooling specifications:
– Coolant capacity: approx. 6.0 liters (6.3 US quarts)
– Thermostat opening: approx. 78–82°C (172–180°F)
– Fully open: approx. 95°C (203°F)
– System pressure: approx. 90 kPa (13 psi)
The radiator is cross-flow aluminum, equipped with an electric fan.
Honda recommends coolant replacement every 40,000 km (25,000 miles) or
two years.
| Intake and Exhaust Systems |
The intake system uses a cast-aluminum intake manifold tuned for
mid-range torque. The throttle body provides smooth air delivery, and a
dry paper air filter protects against particulate contamination.
The exhaust system uses a cast-iron manifold with smooth internal
passages to minimize turbulence. A catalytic converter is located
downstream for emissions control, along with oxygen sensors for
closed-loop fuel metering.
| Ignition and Electrical System |
The ignition system uses a distributor with an internal crank angle
sensor. The ignition coil is integrated into the distributor assembly.
Spark plugs are standard nickel or platinum types with a gap of approx.
1.0–1.1 mm (0.039–0.043 in).
Electrical specifications:
– Alternator: approx. 70–90 amperes
– Starter motor: approx. 1.0–1.2 kW
– System voltage: 12 V
The ECU manages ignition timing based on load, MAP signal, engine
temperature, and rpm.
The F18A3 includes:
– PCV system
– EVAP emissions control system
– Idle-air control valve
– EGR valve for NOx emissions control
– OBD-I or early OBD-II diagnostics depending on market
– Length: 630 mm (24.8 inches)
– Width: 580 mm (22.8 inches)
– Height: 670 mm (26.4 inches)
Dry weight is around 140–150 kg (309–331 lbs).
Recommended service intervals:
– Oil and filter: 8,000–10,000 km (5,000–6,000 mi)
– Air filter: 20,000–30,000 km
– Spark plugs: 30,000–40,000 km (standard), 60,000–80,000 km (platinum)
– Timing belt: every 100,000 km (60,000 miles)
– Valve clearance check: every 40,000 km (25,000 miles)
– Coolant: every 40,000 km or 2 years
– Fuel filter: every 40,000 km (25,000 miles)
– Compression test: 170–200 psi (1,170–1,380 kPa)
– Cylinder head bolts: 30 Nm (22 lb-ft) + 90° + 90°
– Main bearing caps: 60 Nm (44 lb-ft)
– Connecting rod bolts: 40 Nm (30 lb-ft)
– Flywheel bolts: 88 Nm (65 lb-ft)
– Crankshaft pulley bolt: 245 Nm (181 lb-ft)
– Exhaust manifold nuts: 30 Nm (22 lb-ft)
– Intake manifold bolts: 22 Nm (16 lb-ft)
– Spark plugs: 18 Nm (13 lb-ft)
– Oil drain plug: 40 Nm (30 lb-ft)
The Honda F18A3 was used primarily in:
– European-market Honda Accord (mid-1990s)
– Regional Honda and Rover cooperative models
– Replacement and industrial applications in select secondary markets
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