Nissan L18 Specifications
| Engine Model: Nissan L18 |
| Engine Type: 4-cycle inline 4-cylinder SOHC 8-valve liquid-cooled gasoline |
| Total Displacement: 108 cu.in (1.77 L) |
| Rated Engine Power: 98-115 Hp (73-86 kW) at 5600 rpm |
| Fuel System Type: Twin side-draft or single downdraft carburetor |
____________________________________________________________________________________
The Nissan L18 engine is a 1.8-liter
inline-four, overhead-cam gasoline engine produced by Nissan as part of
the legendary L-series family, which includes the L13, L14, L16, L18,
and L20 engines. Introduced in the early 1970s, the L18 gained a
reputation for ruggedness, mechanical simplicity, and excellent
durability under severe operating conditions. Used in both passenger
cars and light commercial vehicles, the L18 became widely known for its
reliability in rally applications, daily commuter use, and global
markets that required robust long-life engines with straightforward
maintenance.
The L-series engines feature cast-iron cylinder blocks, aluminum
overhead-cam cylinder heads, timing-chain valvetrains, strong crankshaft
designs, and simple yet robust fuel and ignition systems. The L18, with
its 1770-cc displacement, sits between the smaller L16 and the larger
L20B in terms of power and torque. It is especially notable for its
torque output at low and mid rpm, making it well-suited for sedans,
trucks, and station wagons.
Even decades after its introduction, the L18 remains admired for its
mechanical longevity, ease of rebuilding, and ability to withstand
significant abuse. Its architecture is straightforward, parts
availability remains excellent, and its tuning potential is well
established in classic car communities. For reliability, simplicity, and
robustness, the Nissan L18 stands as one of Nissan’s most iconic classic
engines.
The Nissan L18 is an inline-four, four-stroke, water-cooled gasoline
engine with a displacement of 1770 cc, or approximately 108.0 cubic
inches. Bore is 85.0 mm (3.35 inches), and stroke is 78.0 mm (3.07
inches), resulting in an oversquare design that favors higher-rpm
breathing while retaining good torque. Compression ratios vary from
8.5:1 to 9.0:1 depending on market, emission levels, and model year.
Power output ranges from 98 to 115 Hp (73 to 86 kW) at 5600 rpm. Maximum
torque output varies from 145 to 155 Nm (107 to 114 lb-ft) at around
3600 to 4400 rpm. The firing order is 1-3-4-2. Idle speed is generally
specified at 700 to 800 rpm depending on carburetor configuration and
emission controls.
The L18 uses a cast-iron cylinder block for strength and durability. The
crankshaft is a robust forged-steel unit supported by five large main
bearings, contributing to long-term stability and smooth operation.
Pistons are aluminum alloy with conventional ring packs consisting of
two compression rings and one oil ring. The connecting rods are forged
steel, designed for long-term reliability with ample bearing surface
area and strong metallurgy.
The cylinder head is made of aluminum alloy, featuring a single overhead
camshaft (SOHC) that operates two valves per cylinder, for a total of
eight valves. The camshaft is driven by a double-row steel timing chain.
Chain tension is maintained by a hydraulic tensioner and a curved chain
guide. Timing chains on L-series engines are known for exceptional
longevity but must be inspected periodically at high mileage.
Valve sizes vary slightly depending on
market and model year, but std values include:
Intake valve diameter: approximately 42 mm (1.65 inches)
Exhaust valve diameter: approximately 35 mm (1.38 inches)
Valve lash adjustment is mechanical, performed with adjustable rocker
arms.
Cold valve clearance specifications are:
- Intake: 0.25 mm (0.010 in)
- Exhaust: 0.30 mm (0.012 in)
The L18 uses a carbureted fuel system. Most versions use twin Hitachi
(licensed SU-type) side-draft carburetors or a single downdraft
carburetor depending on market and application. Some versions,
especially emissions-controlled models, use a feedback carburetor with
additional vacuum and thermal controls.
Fuel is supplied by a mechanical fuel pump mounted to the engine block,
delivering fuel at low pressure (2.5 to 4.0 psi). A replaceable in-line
paper filter protects the carburetor jets and passages from
contamination.
Carburetor features include:
- Idle mixture screw
- Main jet, secondary jet (depending on model)
- Accelerating pump
- Float bowl fuel level control
- Vacuum-controlled secondary throttle (some models)
- Choke system (manual or automatic)
Ignition timing depends on carburetion and emission controls but
typically is base-timed at 8° to 12° BTDC at idle, with centrifugal and
vacuum advance to improve response and fuel economy.
The lubrication system is a wet-sump, full-pressure design with a
trochoid-type oil pump mounted to the engine block. The pump provides
oil to the crankshaft, connecting rods, camshaft bearings, timing chain,
and valve train components.
Oil capacity with filter is 3.7 to 4.0 liters (3.9 to 4.2 U.S. quarts).
Recommended oil viscosity ranges from SAE 10W-30 to 20W-50 depending on
climate.
Oil pressure readings measure:
- At 3000 rpm: 350-450 kPa (50-65 psi)
- At idle: above 70 kPa (10 psi)
Cooling is provided by a belt-driven centrifugal water pump. Coolant
circulates through the engine block, cylinder head, radiator, and heater
core. Thermostat opening temperature is around 82°C (180°F), with full
opening near 95°C (203°F). Cooling system capacity averages 7.0 to 7.5
liters (7.4 to 7.9 quarts).
The system includes:
- Radiator with copper/brass or aluminum construction
- Thermostatic fan clutch or fixed mechanical fan depending on model
year
- Expansion tank / overflow reservoir
- Temperature sender for gauge
| Intake and Exhaust Systems |
Induction is through a cast-aluminum intake manifold matched to the
carburetion type. Twin-carburetor models use independent runners for
improved throttle response. The air cleaner housing may be a round-type
or a flat “pancake” type depending on model.
The exhaust manifold is a cast-iron unit designed for durability and
even exhaust flow. In performance or rally applications, tubular headers
are frequently fitted to increase exhaust scavenging and high-rpm power.
| Ignition and Electrical System |
Ignition is handled by a distributor-based system.
The distributor incorporates:
- Breaker points (early models)
- Electronic ignition module (later models)
- Vacuum advance diaphragm
- Centrifugal advance weights
Spark plugs are NGK B6ES or equivalent, gapped to approximately 0.8 mm
(0.031 in). Charging is provided by a belt-driven alternator producing
between 35 and 50 amperes depending on model year.
Depending on year and market, the L18 may
include:
- Positive crankcase ventilation (PCV)
- Anti-pollution devices such as EGR
- Thermal vacuum switches
- Carburetor anti-dieseling solenoid
- Emissions air pump (some markets)
- Length: approx. 600-610 mm (23.6-24.0 in)
- Width: approx. 520-540 mm (20.5-21.3 in)
- Height: approx. 650-700 mm (25.6-27.6 in)
Dry weight: approx. 145-160 kg (320-353 lbs)
Recommended maintenance includes:
- Oil and filter: every 5000-8000 km (3000-5000 miles)
- Air filter: every 20,000 km (12,000 miles)
- Fuel filter: every 20,000-30,000 km
- Spark plugs: every 15,000-20,000 km
- Valve clearance: every 20,000 km
- Timing chain: inspect at high mileage
- Coolant: every 40,000 km or 2 years
- Compression: healthy range 150-175 psi (1034-1206 kPa), with <10%
variation
- Cylinder head bolts: 100 Nm (74 lb-ft)
- Main bearing caps: 80 Nm (59 lb-ft)
- Connecting rod bolts: 54 Nm (40 lb-ft)
- Flywheel bolts: 98 Nm (72 lb-ft)
- Crankshaft pulley bolt: 155 Nm (114 lb-ft)
- Intake manifold bolts: 22 Nm (16 lb-ft)
- Exhaust manifold nuts: 28 Nm (21 lb-ft)
- Spark plugs: 18 Nm (13 lb-ft)
- Oil drain plug: 34 Nm (25 lb-ft)
The Nissan L18 powered numerous models,
including:
- Nissan 610 Bluebird / 180B
- Nissan 710 / Violet
- Nissan 620 pickup (some trims)
- Nissan Auster
- Nissan Laurel regional variants
- Various commercial vehicles
- Global-market Datsun models
____________________________________________________________________________________
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Industrial Engines Technical Specifications |
| Outboard Engines Technical Specifications |
