Nissan L20B

Nissan L20B engineThe Nissan / Datsun L20B is a carbureted 2.0 liter (1,952 cc, 119.11 cu in) straight-4, four-stroke cycle gasoline engine from Nissan L-family. The Nissan / Datsun L20B motor was produced from 1974 through 1985.

The Nissan (Datsun) L20B engine features OHC valves, wedge-shaped combustion chamber, aluminum cylinder head, and fully balanced five-bearing crankshaft. The cylinder block is cast as a single unit and features deep skirting. The engine is equipped with single, 2-barrel, downdraft carburetor that incorporates a special device to control emission.

The L20B engine has an 85.0 mm (3.35 in) cylinder bore and 86.0 mm (3.38 in) piston stroke with a compression ratio of 8.5:1.

The Nissan L20B engine produced:

  • SAE Gross: 112 PS (110 HP, 82 kW) and 152 Nm (15.5 kg·m, 112 lb·ft)
  • SAE Net: 98 PS (97 HP, 72 kW) and 138 Nm (14.1 kg·m, 102 lb·ft)

The breakdown of the engine code is as follows:

  • L – Engine Family
  • 20 – 2.0 Liter Displacement

General information

Engine Specifications
Engine code L20B
Layout Four stroke, Inline-4 (Straight-4)
Fuel type Gasoline
Production
Displacement 2.0 L, 1,952 cm3 (119.11 cu in)
Fuel system Carburetor
Power adder None
Max. horsepower 112 PS (110 HP, 82 kW)
Max. torque 52 Nm (15.5 kg·m, 112 lb·ft)
Firing order 1-3-4-2
Dimensions (L x H x W):
Weight

Cylinder block

The Nissan-Datsun L20B motor has a cast-iron cylinder block. The cylinder block, a monoblock special casting structure, employs a five-bearing-support system. The cylinder bores are surrounded by cooling jackets and machined directly in the block. The oilways in the block are arranged so that the full-flow oil filter is directly attached to the right-hand side of the block. The Nissan L20B engine cylinder bore is 85.0 mm (3.35 in) and the piston stroke is 86.0 mm (3.38 in), compression ratio rating is 8.5:1.

The crankshaft is a special steel forging; fully balanced, it turns out smooth, dependable power at high speed. The engine uses eight balance weights. The pistons are special aluminum casting with struts to control thermal expansion and have two compression rings and one combined oil ring. The piston heads are slightly dished. The piston pin is a special hollow steel shaft. It is full-floating fit to the piston and press-fit to the connecting rods. The connecting rods are special forged steel.

Cylinder block
Cylinder block alloy Cast iron
Compression ratio: 8.5:1
Cylinder bore: 85.0 mm (3.35 in)
Piston stroke: 86.0 mm (3.38 in)
Number of piston rings (compression / oil): 2 / 1
Number of main bearings: 5
Cylinder inner diameter (standard): 85.000-85.050 mm (3.3465-3.3484 in)
Piston skirt diameter (standard): 84.985-85.035 mm (3.3459-3.3478 in)
Piston pin outer diameter: 20.993-20.998 mm (0.8265-0.8267 in)
Piston ring side clearance: Top 0.040-0.073 mm (0.0016-0.0029 in)
Second 0.030-0.070 mm (0.0012-0.0028 in)
Piston ring end gap: Top 0.25-0.40 mm (0.0098-0.0157 in)
Second 0.30-0.50 mm (0.0118-0.0197 in)
Oil 0.30-0.90 mm (0.012-0.035 in)
Connecting rod center distance: 146.00 mm (5.75 in)
Crankshaft journal diameter: 59.942-59.955 mm (2.3599-2.3604 in)
Crankpin diameter: 49.961-49.974 mm (1.9670-1.9675 in)
Crankshaft center distance: 43.00 mm (1.6929 in)

Cylinder head

The cylinder head is made of light and strong aluminum alloy with good cooling efficiency; it contains wedge-type combustion chambers. A special aluminum bronze valve seat is used on the intake valve, while a heat resistant steel valve seat is installed on the exhaust valve. These parts are all hot press-fitted.

The camshaft is made of special cast iron and located inside the rocker cover. Four aluminum alloy brackets support camshaft. Camshaft bearings are lubricated from oil holes which lead to the main oil gallery of the cylinder head. Concentric passages are drilled in the front and rear parts of the camshaft.

The valve system has a pivot type rocker arm that is activated directly by the cam mechanism. The Nissan L20B motor use the dual-type valve springs. Intake valves are 42 mm (1.65 in) in diameter and the exhaust valves are 35 mm (1.37 in). The intake valve duration is 248°, valve lift is 10.0 mm (0.39 in); the exhaust valve duration is 248°, valve lift is 10.5 mm (0.41 in).

The camshaft is driven by a double row roller chain driven by the crankshaft. The tension of the chain is controlled by a chain tensioner which is operated by spring and oil pressure.

The intake manifold is made of cast aluminum alloy and the exhaust manifold is made of cast iron.

Cylinder head
Valve Arrangement: OHV, chain drive
Valves: 8 (2 valves per cylinder)
Intake/Exhaust duration: 248°/248°
Valve head diameter: INTAKE 42.0 mm (1.6535 in)
EXHAUST 35.0 mm (1.3780 in)
Valve length: INTAKE 114.9-115.2 mm (4.524-4.535 in)
EXHAUST 115.7-116.0 mm (4.555-4.567 in)
Valve stem diameter: INTAKE 7.965-7.980 mm (0.3136-0.3142 in)
EXHAUST 7.945-7.960 mm (0.3128-0.3134 in)
Valve spring free length: INTAKE Outer: 49.98 mm (1.968 in)
Inner: 44.85 mm (1.766 in)
EXHAUST Outer: 49.98 mm (1.968 in)
Inner: 44.85 mm (1.766 in)
Valve lift: INTAKE 10.5 mm (0.413 in)
EXHAUST 10.5 mm (0.413 in)
Camshaft robe lift: INTAKE 7.00 mm (0.2753 in)
EXHAUST 7.00 mm (0.2753 in)
Outer camshaft journal diameter: 47.949-47.962 mm (1.8878-1.8883 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt 60-85 Nm; 6.5-8.5 kg·m; 47.0-61.5 ft·lb
Connecting rod big end nuts 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb
Flywheel bolt 137-157 Nm; 14.0-16.0 kg·m; 101-116 ft·lb
Main bearing cap bolt 44-54 Nm; 4.5-5.5 kg·m; 33-40 ft·lb
Camshaft sprocket bolt 118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb
Oil pan bolts 6-9 Nm; 0.6-0.0 kg·m; 4.3-6.5 ft·lb
Oil pump bolt 11-15 Nm; 1.1-1.5 kg·m; 8-11 ft·lb
Oil pan drain plug 20-30 Nm; 2.0-3.0 kg·m; 14-22 ft·lb
Rocker pivot lock nut 49-59 Nm; 5.0-6.0 kg·m; 36-44 ft·lb
Camshaft locating plate bolts 6-9 Nm; 0.6-0.9 kg·m; 4.3-6.5 ft·lb
Manifold nuts 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Fuel pump nuts 12-18 Nm; 1.2-1.8 kg·m; 8.7-13.0 ft·lb
Crank pulley nut 118-157 Nm; 12.0-16.0 kg·m; 87-116 ft·lb

Maintenance data

Valve clearance (HOT)
Intake valve 0.25 mm (0.010 in)
Intake valve 0.30 mm (0.012 in)
Valve clearance (COLD)
Intake valve 0.20 mm (0.008 in)
Exhaust valve 0.25 mm (0.010 in)
Compression pressure
Standard 12.0 kg/cm2 (11.77 bar, 171 psi) / 350 rpm
Minimun 9.0 kg/cm2 (8.83 bar, 128 psi) / 250 rpm
Oil system
Oil consumption , L/1000 km (qt. per miles) up to 0.5 (1 qt. per 1200 miles)
Recommended engine oil 5W-30
5W-40
10W-30
10W-40
Oil type API SE
Engine oil capacity (Refill capacity) With oil filter: 4.4 l
Without oil filter: 3.9 l
Oil change interval, km (miles) 12,000 (7,500)
Oil pressure, kg/cm2 (psi) 3.5-4.2 (49.8-56.9) at 2,000 rpm
Ignition system
Spark plug USA models: BP6ES-11 (NGK), L45PW-11 (Hitachi)
Canada models: BPR6ES (NGK)
Spark plug gap USA models: 1.0-1.1 mm (0.039-0.043 in)
Canada models: 0.8-0.9 mm (0.03-0.035 in)
Spark plug tightening torque 15-25 Nm; 1.5-2.5 kg·m; 11-15 ft·lb

Vehicle applications

Model Years Produced
Datsun 610 1974–1976
Datsun 710 1975–1977
Datsun 620 1975–1979
Datsun 200SX (S10) 1975–1979
Datsun 200B 1977–1981
Datsun 510 1978–1981
Datsun 720 1979.5–1980
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