Nissan GA15 Specifications
| Engine Model: Nissan GA15 |
| Engine Type: 4-cycle inline 4-cylinder SOHC 12-valve liquid-cooled gasoline |
| Total Displacement: 91.4 cu.in (1.49 L) |
| Rated Engine Power: 85-94 Hp (63-70 kW) at 6000 rpm |
| Fuel System Type: Single or two barrel downdraft carburetor |
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The Nissan GA15 (GA15S) is a 1.5-liter
inline-four, water-cooled, carbureted gasoline engine that belongs to
Nissan’s GA-series family, which includes the GA13, GA14, GA15, and GA16
engine groups. Produced from the late 1980s through the 1990s, the GA15S
served as a foundation powerplant for compact Nissan cars such as the
Sunny, Sentra, and Pulsar in markets where electronic fuel injection was
either unnecessary or cost-prohibitive.
The GA15S occupies the middle ground between
older E-series engines and the more sophisticated GA15DE multi-point
fuel-injected version. The engine’s design philosophy emphasizes
mechanical simplicity, reliability, low running costs, and ease of
service, making it ideal for high-mileage fleet vehicles, taxis, and
regional models operating in developing markets.
The GA15 retains the core construction of the GA-series—cast-iron block,
aluminum cylinder head, timing-chain-driven valvetrain, and robust
internal architecture—but operates using a downdraft carburetor instead
of fuel injection. This allows the engine to be serviced without
specialized diagnostic equipment, while still offering improved
refinement compared with earlier carbureted engines.
Its balanced rotating assembly, efficient
combustion chamber design, and moderate compression ratio give the GA15S
a reputation for smooth operation and long service life. Although not as
powerful or efficient as the GA15DE, the carbureted GA15S remains a
dependable and economical choice for compact commuter vehicles.
The Nissan GA15 is a four-stroke, inline-four gasoline engine with a
total displacement of 1497 cc, or approximately 91.4 cubic inches. Bore
is 73.6 mm (2.90 inches), and stroke is 88.0 mm (3.46 inches), creating
a long-stroke configuration optimized for low-end and mid-range torque.
The compression ratio for most GA15S versions ranges between 9.5:1 and
9.9:1 depending on emissions requirements and market calibrations.
Power output varies by carburetor type, emissions equipment, and region
but typically ranges from 85 to 94 horsepower (63 to 70 kW) at
approximately 6000 rpm. Maximum torque output is generally between 120
and 128 Nm (89 to 94 lb-ft) at around 3600 to 4000 rpm. Idle speed is
normally set at 750 ± 50 rpm. The firing order is 1-3-4-2.
The crankshaft is a forged-steel, fully counterweighted unit supported
by five main bearings, allowing smooth rotation and long service life
even under high mileage. The connecting rods are forged steel with
full-floating wrist pins, providing excellent durability. Pistons are
aluminum alloy with molybdenum-coated skirts to reduce friction and
promote efficient warm-up. Piston rings consist of two compression rings
and one oil-control ring.
The GA15S uses an aluminum cylinder head with a single overhead camshaft
(SOHC) and typically a 12-valve layout (three valves per cylinder: two
intake and one exhaust). Some transitional market versions used a DOHC
16-valve head paired with a carburetor, but the majority of GA15S
engines worldwide are SOHC 12-valve designs.
The SOHC design uses rocker arms and hydraulic or mechanical lash
adjusters depending on variant. Most GA15S engines employ mechanical
valve lash adjustment, requiring periodic clearance checks.
Cold valve lash
specifications typically fall within:
Intake: 0.22 mm (0.009 inches)
Exhaust: 0.28 mm (0.011 inches)
The camshaft is driven by a roller-type timing chain, offering a long
service life and minimal maintenance. Chain tension is maintained by an
automatic hydraulic tensioner using engine oil pressure. The combustion
chambers are wedge or pent-roof shaped depending on head design,
providing efficient air-fuel mixing and combustion characteristics.
The GA15S uses a downdraft carburetor rather than electronic fuel
injection.
Carburetor types vary by market:
- Standard single-barrel carburetor
- Two-stage (primary/secondary) carburetor
- Feedback carburetor with oxygen sensor and mixture-control solenoid
Fuel is delivered by a mechanical fuel pump mounted on the engine block
and driven by an eccentric on the camshaft. Fuel pressure is typically
between 20 and 30 kPa (3 to 4 psi). A paper-element inline fuel filter
removes contaminants prior to the carburetor.
Carburetor subsystems include:
- Idle mixture circuit
- Air-bleed system
- Accelerator pump
- Power valve for enrichment
- Vacuum-controlled secondary throttle (two-barrel versions)
- Choke (manual or automatic)
Feedback versions feature:
- Oxygen sensor
- ECU-controlled air-bleed solenoid
- Throttle switch
- Idle-up solenoid for air conditioning
These systems ensure stable operation, reasonable emissions compliance,
and predictable drivability across temperature and load conditions.
The GA15S uses a wet-sump, full-pressure lubrication system. A
trochoid-type oil pump mounted on the crankshaft nose draws oil through
a mesh strainer and pumps it through a full-flow spin-on oil filter
before delivering it to the crankshaft bearings, connecting rod
bearings, camshaft bearings, and valvetrain components. Engine oil also
lubricates the timing chain and hydraulic tensioner.
Oil capacity with filter is generally 3.1 to 3.3 liters (3.3 to 3.5 U.S.
quarts). Recommended oil viscosity ranges from SAE 5W-30 to 10W-30
depending on climate. Oil pressure at 3000 rpm is typically 350 to 450
kPa (50 to 65 psi), with idle pressure above 70 kPa (10 psi).
Cooling is provided by a belt-driven centrifugal water pump that
circulates coolant through the block, cylinder head, radiator, and
heater core. The thermostat begins opening at about 82°C (180°F) and
reaches full opening at roughly 95°C (203°F). Cooling system capacity is
around 5.0 liters (5.3 U.S. quarts). An electric radiator fan ensures
proper cooling during idle and low-speed operation.
The cooling system includes:
- Overflow reservoir
- Pressure cap (approx. 88 kPa / 13 psi)
- Heater core bypass passages
- Temperature sensor for gauge or ECU-related functions
Proper cooling system maintenance is vital for long-term engine
longevity.
| Intake and Exhaust Systems |
The induction system consists of a molded plastic air intake duct,
resonator chambers to reduce intake noise, a paper air filter element,
and an aluminum intake manifold. Carbureted intake manifolds typically
use smaller runners optimized for low-rpm torque.
The exhaust manifold is cast iron, leading to a downpipe and catalytic
converter (in regulated markets). Some non-catalyst markets use
straight-through exhaust systems. Feedback-carbureted variants use an
oxygen sensor to monitor exhaust oxygen content for mixture adjustments.
| Ignition and Electrical System |
Ignition is handled by a distributor-based system.
The distributor contains:
- Pickup coil or magnetic reluctor
- Mechanical and vacuum advance mechanisms (early versions)
- Electronic ignition module (later versions)
A single ignition coil supplies high-voltage current to the distributor
cap. The distributor rotor routes spark to the cylinders in the 1-3-4-2
firing order.
Spark plug specification: NGK BPR5ES or equivalent
Spark plug gap: approx. 1.0 mm (0.039 inches)
Alternator output ranges between 55 and 70 amperes. Electrical system
voltage is 12 V DC. The starter motor is a reduction-gear type capable
of reliable cold-weather operation.
Depending on market requirements, the GA15S
may include:
- PCV (positive crankcase ventilation)
- EVAP charcoal canister
- EGR system
- Secondary air-injection pump (early models)
- Throttle-position switch for feedback systems
- Idle-up solenoid for power steering or air conditioning
Length: 560–580 mm (22.0–22.8 inches)
Width: 510–520 mm (20.1–20.5 inches)
Height: 620–640 mm (24.4–25.2 inches)
Dry weight: 105–115 kg (231–254 lbs), depending on carburetor type and
accessories.
Routine maintenance includes:
- Oil and filter: 5000–10,000 km (3000–6000 miles)
- Spark plugs: 20,000–30,000 km
- Air filter: 20,000 km
- Fuel filter: 20,000–30,000 km
- Valve clearance: 40,000–60,000 km
- Coolant: 40,000 km or 2 years
- Timing chain: inspect at high mileage
- Compression: 1300–1500 kPa (189–218 psi), variation max 100 kPa (15
psi)
- Cylinder head bolts: 98 Nm (72 lb-ft)
- Main bearing caps: 50 Nm (37 lb-ft)
- Connecting rod bolts: 30 Nm (22 lb-ft) + 60°
- Camshaft cap bolts: 9 Nm (7 lb-ft)
- Flywheel bolts: 88 Nm (65 lb-ft)
- Crankshaft pulley bolt: 120 Nm (89 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 GA15S engine was used in a variety of
Nissan compact vehicles:
- Nissan Sunny (B12, B13—carbureted trims)
- Nissan Sentra (selected carbureted models)
- Nissan Pulsar regional variants
- Nissan Lucino base models
- Taxi and fleet vehicles in Asia, Africa, and Latin America
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