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Nissan CA20S Specifications
| Engine Model: Nissan CA20S |
| Engine Type: 4-cycle inline 4-cylinder SOHC 8-valve liquid-cooled gasoline |
| Total Displacement: 120.5 cu.in (1.97 L) |
| Rated Engine Power: 90-102 Hp (67-75 kW) at 5200 rpm |
| Fuel System Type: Single barrel or twin barrel carburetor |
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| General Technical Data |
The Nissan CA20S engine is a 2.0 liter inline four-cylinder gasoline engine developed during the 1980s as part of the CA engine family. It represents the carbureted version of the CA20 series, positioned above the CA18S and below the fuel injected CA20E. The CA20S was engineered for simplicity, durability, and ease of service while providing adequate torque for everyday driving.
It featured a cast iron block, an aluminum
cylinder head, belt driven camshaft, and a simple single barrel or twin
barrel carburetor depending on market. The engine was used mainly in
compact and mid-size passenger cars such as the Nissan Bluebird and
Nissan Auster. Its design favored long service life, low operating cost,
and very stable performance under varying fuel quality conditions common
in its production era.
The CA20S is known for its conservative design philosophy. By using a
carburetor instead of electronic injection, Nissan ensured minimal
electronic dependence. This made the engine popular in markets where
simple mechanical systems were preferred for maintenance and long-term
reliability.
The smooth torque curve and moderate
compression ratio make the engine tolerant of a wide range of fuels.
Although not a high-performance engine, the CA20S provides a reliable
powerplant with predictable behavior. It remains appreciated by
restorers of classic Nissan vehicles due to its straightforward
construction.
The CA20S engine has a displacement of 1974 cc. The bore is 84.5 mm,
equivalent to 3.33 inches, and the stroke is 88.0 mm, equivalent to 3.46
inches. This long stroke configuration gives the engine a
torque-oriented character suited for economical driving. The compression
ratio varies slightly by market, typically around 8.5 to 9.0 to 1.
The engine operates on the four stroke Otto
cycle and uses a single overhead camshaft operating eight valves. The
firing order is 1-3-4-2. The crankshaft rotates on five main bearings
that ensure rigidity and smooth operation. Pistons are cast aluminum
with two compression rings and one oil control ring. Connecting rods are
forged steel with full floating piston pins.
Maximum power output of the CA20S is generally in the range of 90 to 102
horsepower at approximately 5200 revolutions per minute depending on
carburetor version and emission calibration. Maximum torque is around
110 to 115 lb-ft or 150 to 155 Nm at around 2800 to 3200 rpm. Idle speed
is typically 700 to 800 rpm. The engine redline is around 6000 rpm. The
cooling system is water cooled with a belt driven mechanical pump.
Ignition is handled by a conventional distributor with mechanical and
vacuum advance systems.
| Fuel System |
The CA20S uses a carburetor-based fuel metering system. Depending on market and emission requirements, Nissan installed either a simple single venturi carburetor or a more advanced two-barrel carburetor with primary and secondary circuits. Fuel is delivered by a mechanical diaphragm fuel pump driven by the camshaft. Fuel pressure is low, typically in the range of 3 to 5 psi, and suitable for carburetor float valve operation.
A metal or paper element fuel filter is installed in line before the carburetor. The carburetor includes choke mechanisms, accelerator pump, idle mixture screw, and various air bleed circuits for proper atomization. In colder climates, a hot air intake system with a thermostatic control ensures improved vaporization.
| Lubrication System |
The lubrication system is a full pressure wet sump design using a trochoid oil pump driven by the crankshaft. Oil is drawn from the sump through a pickup screen and pumped through a full flow oil filter located on the engine block. Lubrication passages deliver oil to the main bearings, connecting rod bearings, camshaft bearings, and valve train components.
The system also lubricates the timing belt tensioner. Oil pressure at 3000 rpm is typically around 45 to 55 psi and at idle around 10 to 15 psi. The oil capacity is approximately 3.5 to 4.0 liters or 3.7 to 4.2 US quarts. Recommended oil viscosity is SAE 10W-30 or 10W-40 depending on climate. Oil and filter replacement intervals are generally every 5000 km or 3000 miles under normal driving conditions.
| Cooling System |
The engine uses a liquid cooling system consisting of a belt driven centrifugal water pump, aluminum radiator, thermostat, and coolant passages in the block and cylinder head. The thermostat begins to open at approximately 82 C or 180 degrees F. Cooling system capacity is around 6.0 to 6.5 liters or about 6.3 to 6.8 US quarts.
The radiator cap typically maintains system pressure at around 13 psi. Coolant should be a 50 50 mixture of ethylene glycol antifreeze and water. The system includes a heater core connected through bypass hoses. Regular coolant replacement is recommended every two years to prevent corrosion in the aluminum cylinder head.
| Intake and Exhaust Systems |
The induction system consists of an air cleaner housing with a replaceable paper element, intake ducting, and the carburetor mounted on an aluminum intake manifold. The intake manifold design is optimized for equal distribution to all cylinders.
The exhaust system features a cast iron exhaust manifold connected to a single downpipe and catalytic converter in later emissions versions. Earlier or non- emission models use a simple exhaust pipe system. The exhaust manifold is designed to reduce hot spots and maintain uniform temperature.
| Ignition and Electrical System |
The ignition system is a conventional design using a mechanical distributor with rotor, cap, ignition coil, and spark plug wires. Distributor advance is both mechanical centrifugal and vacuum operated for improved part load efficiency. Recommended spark plug type is a standard nickel alloy plug with heat range suitable for moderate compression engines.
Spark plug gap is typically around 0.9 mm or 0.035 inches. The alternator provides 12-volt electrical power with typical output around 50 to 60 amperes. The starter motor is a direct drive or reduction type depending on model year.
| Valve Train and Timing Belt |
The single overhead camshaft is driven by a toothed rubber timing belt. The belt also drives the water pump. Valve clearance is adjusted by shim and bucket on some versions and by rocker arms with adjustment screws on others depending on production year. The timing belt replacement interval is typically every 100000 km or about 60000 miles. The camshaft operates two valves per cylinder with intake and exhaust valves arranged in line. Valve springs are single coil with dampers.
| Other Systems |
The engine includes a positive crankcase ventilation system using a PCV valve mounted on the rocker cover. Blow by gases are routed into the intake manifold for re burning. The evaporative emission control system uses a charcoal canister to store fuel vapors which are later purged into the intake. The engine also includes a vacuum operated hot air intake control on some versions. The cooling system uses an overflow reservoir to maintain coolant level during thermal expansion.
| Dimensions and Weight |
The CA20S engine has compact external dimensions suitable for front wheel drive and rear wheel drive vehicles. Overall length is approximately 600 mm or 23.6 inches. Width is around 550 mm or 21.6 inches. Height is roughly 650 mm or 25.6 inches. Dry weight is approximately 125 to 135 kg or 275 to 298 lbs depending on accessory equipment installed. The cast iron block contributes to durability and stable thermal behavior.
| Maintenance Data |
Routine maintenance ensures long engine life. Oil change interval is
every 5000 km or 3000 miles. Air filter replacement is recommended every
20000 km or 12000 miles. Spark plugs should be inspected at every oil
change and replaced every 20000 to 30000 km or 12000 to 18000 miles.
Timing belt replacement is required at 100000 km or 60000 miles. Valve
clearance should be checked every 40000 km or 25000 miles. Fuel filter
inspection should occur at every major service interval. Carburetor base
gasket and vacuum hoses should be inspected for leaks regularly.
Compression pressure when new is typically around 150 to 170 psi with a
minimum acceptable value around 120 psi. Cylinder compression variation
between cylinders should not exceed 10 percent. Idle speed is adjusted
through the carburetor idle screw and should be maintained at 700 to 800
rpm. Ignition timing is normally set around 10 degrees before top dead
center at idle with vacuum advance disconnected. Fuel mixture must be
adjusted to maintain smooth idle and correct emissions.
| Tightening Torques |
Cylinder head bolts should be tightened in stages to approximately 88 Nm or 65 lb-ft. Main bearing cap bolts require around 70 Nm or 52 lb-ft. Connecting rod bolts should be tightened to about 40 Nm or 30 lb-ft. Flywheel bolts are tightened to around 90 Nm or 66 lb-ft. Intake manifold bolts require about 25 Nm or 18 pound- feet. Exhaust manifold nuts need around 35 Nm or 26 lb-ft. Spark plugs are tightened to 18 Nm or 13 lb-ft. Oil drain plug torque is about 35 Nm or 26 lb-ft.
| Vehicle Applications |
The CA20S engine was installed in several Nissan models especially in the 1980s. Common applications include the Nissan Bluebird series, Nissan Auster, and some versions of the Nissan Stanza depending on market. It was primarily used in rear wheel drive and front wheel drive layouts. The engine served as a reliable mid- range option offering good balance between fuel economy and usable torque. Its simplicity made it suitable for markets requiring low maintenance engines.
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