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Mitsubishi 4G13 Specifications
| Engine Model: Mitsubishi 4G13 |
| Engine Type: 4-cycle inline 4-cylinder SOHC or DOHC liquid-cooled gasoline |
| Total Displacement: 79.2 cu.in (1.29 L) |
| Rated Engine Power: 55-88 Hp (40-65 kW) at 6500 rpm |
| Fuel System Type: Carburetor or electronic fuel injection |
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| General Technical Data |
The Mitsubishi 4G13 is a 1.3-liter inline-four, four-stroke, water-cooled gasoline engine belonging to Mitsubishi's long-lived Orion family of small displacement engines. Introduced in the late 1970s, it became one of the most widely used powerplants in compact Mitsubishi passenger cars and light sedans. The engine was produced in various forms from simple carbureted units to more advanced versions equipped with electronic fuel injection (EFI) and, in some markets, catalytic emission control.
It earned a reputation for reliability,
economy, and ease of service. The 4G13's design reflected Mitsubishi's
emphasis on efficiency and low emissions during a period of tightening
environmental regulations and evolving automotive technology.
In its early years, the 4G13 powered small front-wheel-drive and
rear-wheel-drive models such as the Lancer, Mirage, Colt, and Minica.
With its modest output and strong low-speed torque, the engine provided
dependable daily performance and long service life.
Later EFI and DOHC versions introduced through
the 1990s improved power delivery, fuel economy, and compliance with
Euro and Japanese emission standards. The 4G13 thus bridged generations
of Mitsubishi small engines and remained in production for nearly three
decades, symbolizing durability and simplicity.
The Mitsubishi 4G13 is an inline four-cylinder engine with a total
displacement of 1,298 cc (79.2 cubic inches). Bore and stroke measure
71.0 mm (2.80 inches) and 82.0 mm (3.23 inches) respectively, giving the
engine an undersquare configuration favoring torque and fuel efficiency.
The compression ratio varied depending on the
version and market-typically 9.0:1 for carbureted types and up to 9.5:1
for later EFI models. The engine block is made of cast iron for strength
and longevity, while the cylinder head is aluminum alloy for weight
reduction and improved heat dissipation.
The 4G13 operates on the four-stroke Otto cycle with a firing order of
1-3-4-2. The crankshaft is supported by five main bearings, ensuring
smooth operation and minimal vibration. Early carbureted versions used a
single overhead camshaft (SOHC) with eight valves (two per cylinder),
actuated by rocker arms through a toothed rubber timing belt.
Later fuel-injected variants adopted twelve- or
sixteen-valve arrangements with either improved SOHC or dual overhead
camshaft (DOHC) layouts. The valves are arranged in a cross-flow
configuration with centrally located spark plugs for efficient
combustion. Hydraulic or adjustable tappets were used depending on model
year and production origin.
Power output for the 4G13 ranges from approximately 55 to 88 Hp (40 to
65 kW, 54 to 87 brake horsepower) depending on configuration,
compression ratio, and induction system. Peak torque output varies from
100 to 120 Nm (74 to 89 lb-ft) around 3,000 to 4,500 revolutions per
minute. The engine's maximum speed is approximately 6,500 rpm with a
redline near 6,800 rpm. Idle speed is 750 ± 50 rpm. The engine runs on
unleaded gasoline with a minimum octane rating of 91 RON (87 AKI).
| Fuel System |
Early 4G13 engines used a downdraft or sidedraft carburetor-usually a single-barrel Mikuni or Keihin unit. These carburetors employed vacuum-operated secondary circuits and manual or automatic choke systems for cold starting.
The fuel was delivered through a mechanical diaphragm pump driven by the
camshaft and regulated by a float chamber. Mixture adjustment was simple
and serviceable, contributing to the engine's reputation for ease of
maintenance. The carbureted fuel system operated at a pressure of about
30 to 40 kPa (4 to 6 psi).
Later versions adopted an electronic fuel injection (EFI) system
controlled by an engine control unit (ECU). The EFI system used
multi-point injectors mounted in the intake manifold near each intake
valve, with an electric fuel pump in the tank supplying fuel at
approximately 300 kPa (43 psi). A pressure regulator maintained constant
differential pressure relative to manifold vacuum.
The ECU monitored signals from sensors such as throttle position, intake air temperature, oxygen, and crank angle to determine injection duration and timing. The EFI system improved throttle response, cold-start performance, and fuel economy while meeting emission standards. The fuel filter was a replaceable inline type recommended for replacement every 40,000 km (25,000 miles).
| Lubrication System |
The lubrication system is a fully pressurized wet-sump type using a trochoid oil pump driven directly by the crankshaft. Oil is drawn from the sump through a mesh strainer and delivered under pressure to the main bearings, connecting rod journals, camshaft bearings, and valve train components. The system incorporates a full-flow spin-on oil filter located on the right side of the block.
Oil pressure at normal operating temperature is approximately 300 to 400
kPa (44 to 58 psi) at 3,000 rpm, and not less than 80 kPa (12 psi) at
idle. Piston cooling oil jets were not fitted to early models but were
added in later EFI variants to enhance piston crown cooling and prevent
detonation under high load.
Oil capacity with filter change is 3.3 liters (3.5 US quarts, 2.9
Imperial quarts). Recommended oil viscosity is SAE 10W-30 or 10W-40
meeting API SG or higher classification, depending on ambient
temperature. The positive crankcase ventilation (PCV) system routes
blow-by gases back to the intake for re-combustion, helping control
emissions. Oil and filter changes are recommended every 10,000 km (6,000
miles) or six months, whichever comes first.
| Cooling System |
The 4G13 employs a pressurized liquid cooling system with a belt-driven centrifugal water pump and a cross-flow radiator. Coolant circulates through the cylinder block, head, radiator, and heater core. A thermostat begins to open at approximately 82 C (180°F) and is fully open near 95°C (203°F).
The radiator features a cap rated around 88 kPa (13 psi) to maintain
boiling resistance. Depending on the model, either a mechanical fan with
viscous clutch or an electric fan controlled by a thermal switch is
used. Total coolant capacity is approximately 5.5 liters (5.8 US quarts,
4.8 Imperial quarts).
A 50/50 mixture of ethylene glycol antifreeze and distilled water is
recommended, providing freeze protection to -35°C (-31°F). Coolant
should be replaced every 40,000 km (25,000 miles) or every two years. A
coolant temperature sensor supplies input to the ECU in EFI models,
while earlier carbureted versions used a simple thermoswitch for the
temperature gauge and fan control.
| Intake and Exhaust Systems |
The intake manifold on early engines was cast aluminum, designed for
uniform air distribution and moderate intake velocity to enhance fuel
atomization. Later EFI versions employed composite or lightweight
aluminum manifolds with tuned runner lengths optimized for mid-range
torque. The throttle body diameter ranged from 40 to 46 mm (1.57 to 1.81
inches). Air was filtered by a replaceable dry-type paper element,
typically serviced every 20,000 km (12,000 miles).
The exhaust system used a cast-iron manifold leading into a single
downpipe and catalytic converter (for EFI or late-carbureted
emission-controlled variants). Oxygen sensors were integrated for
closed-loop fuel control in EFI versions. The exhaust diameter ranged
from 38 to 45 mm (1.5 to 1.8 inches), depending on application. Exhaust
gas recirculation (EGR) was adopted on certain models to reduce nitrogen
oxide emissions.
| Ignition and Electrical System |
Early 4G13 engines employed a conventional distributor-type ignition system with mechanical advance and vacuum diaphragm. The distributor, driven by the camshaft, contained the ignition coil and contact breaker points, later replaced by electronic ignition modules.
Later EFI versions adopted fully electronic distributorless ignition
(DIS) with crank angle and camshaft sensors, and individual coil packs
controlled by the ECU. The spark plugs are typically NGK BPR6ES or
equivalent, with a gap of 1.0 millimeter (0.039 inch). Replacement is
recommended every 20,000 to 30,000 km (12,000 to 18,000 miles).
The alternator is rated between 60 and 75 amperes, depending on year and
accessories. The starting motor is a 12-volt reduction-gear type rated
at approximately 1.0 kilowatt. The battery capacity is typically 36 to
45 ampere-hours. The system operates on a 12-volt DC electrical circuit
with negative ground. All EFI models are equipped with OBD-I or OBD-II
diagnostic capability depending on market.
| Valve Timing and Drive Mechanism |
The camshaft(s) are driven by a toothed rubber timing belt also driving the water pump. Belt replacement interval is 90,000 to 100,000 km (55,000 to 62,000 miles). Proper tension is maintained by a spring-loaded automatic tensioner.
Timing marks on the crankshaft and camshaft sprockets ensure correct alignment during servicing. Early SOHC versions operate two valves per cylinder, while later variants feature four valves per cylinder, providing improved breathing and efficiency. Variable valve timing was not used on this engine.
| Other Systems |
The positive crankcase ventilation system maintains proper crankcase pressure and reduces oil vapor emissions. An evaporative emission control (EVAP) system was added in later models, collecting fuel vapors from the tank and routing them through a charcoal canister for combustion. Some EFI versions incorporated an idle air control (IAC) valve controlled by the ECU to stabilize idle under varying loads.
An EGR system and catalytic converter were fitted on emission-controlled vehicles to comply with Japanese and European standards. The alternator belt and accessory drive belt should be inspected every 20,000 km (12,000 miles) for wear and tension.
| Dimensions and Weight |
Overall engine length is approximately 620 mm (24.4 inches), width 580 mm (22.8 inches), and height 670 mm (26.4 inches). The dry weight of the carbureted version is around 110 kg (243 lbs), while the EFI variant with catalytic converter and additional sensors weighs approximately 120 kg (265 lbs). Engine mounting uses three rubber-isolated mounts to reduce vibration and noise transmission to the chassis.
| Maintenance Data |
To ensure long service life, regular maintenance is essential. Engine oil and filter should be changed every 10,000 km (6,000 miles). Valve clearance (for adjustable tappet types) must be checked every 40,000 km (25,000 miles) with clearances of 0.20 mm (0.008 in) intake and 0.30 mm (0.012 in) exhaust at cold condition. Spark plugs are replaced every 20,000 km (12,000 miles) unless platinum-tipped, which can last up to 60,000 km (37,000 miles).
Air filters are replaced every 20,000 km (12,000 miles). Coolant is renewed every two years or 40,000 km (25,000 miles). The fuel filter and PCV valve are inspected at every major service interval. Compression pressure should be approximately 1,200 kPa (174 psi) with a minimum limit of 1,000 kPa (145 psi). Maximum difference between cylinders should not exceed 100 kPa (15 psi).
Dimensions of key components such as piston pin diameter (18 mm / 0.71 in), connecting rod length (129 mm / 5.08 in), and compression height (31 mm / 1.22 in) reflect the engine's compact yet robust construction. The crankshaft journal diameter is 48 mm (1.89 in) main and 43 mm (1.69 in) rod journals. Standard piston-to-bore clearance is 0.03 to 0.05 mm (0.0012 to 0.0020 in).
| Tightening Torques |
Cylinder head bolts: first 30 Nm (22 lb-ft), second 60 Nm (44 lb-ft),
then turn 90 degrees.
Main bearing cap bolts: 70 Nm (52 lb-ft).
Connecting rod bolts: 40 Nm (30 lb-ft) plus 90 degrees.
Camshaft bearing cap bolts: 12 Nm (9 lb-ft).
Flywheel bolts: 85 Nm (63 lb-ft).
Crankshaft pulley bolt: 160 Nm (118 lb-ft).
Spark plugs: 18 Nm (13 lb-ft).
Oil drain plug: 35 Nm (26 lb-ft).
Intake manifold bolts: 25 Nm (18 lb-ft).
Exhaust manifold nuts: 30 Nm (22 lb-ft).
Valve cover bolts: 8 Nm (6 lb-ft).
Engine mount bolts: 60 Nm (44 lb-ft).
| Vehicle Applications |
The Mitsubishi 4G13 engine was fitted to numerous Mitsubishi vehicles
and models produced under license by other manufacturers.
Key applications include:
- Mitsubishi Lancer (A70 through CK2 series, 1979-2005)
- Mitsubishi Mirage / Colt (1983-2003)
- Mitsubishi Dingo and Space Star in select markets
- Proton Saga, Wira, and Satria (Malaysia) under joint production
agreements
- Hyundai Pony and Excel (early licensed versions)
- Mitsubishi Minica and Minicab (1.3-liter export variants)
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