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Mitsubishi 4B11 Specifications
| Engine Model: Mitsubishi 4B11 |
| Engine Type: 4-cycle inline 4-cylinder DOHC 16-valve liquid-cooled gasoline |
| Total Displacement: 121.9 cu.in (1.99 L) |
| Rated Engine Power: 147-158 Hp (110-118 kW) at 6000 rpm |
| Fuel System Type: Sequential multi-point electronic fuel injection |
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| General Technical Data |
The Mitsubishi 4B11 is a 2.0-liter inline-four gasoline engine developed as part of the modern 4B1-series, introduced to replace earlier 4G9 and 4G6 engines in Mitsubishi’s passenger-car lineup. Designed with a strong emphasis on improved fuel efficiency, reduced emissions, and robust performance, the 4B11 incorporates aluminum-intensive construction, a DOHC 16-valve valvetrain, advanced continuously variable valve timing, and modern electronic management systems.
It is widely recognized for its smooth
operation, high reliability, and responsive torque delivery across a
broad rpm range. The 4B11 platform appears in a wide variety of
Mitsubishi models, and its architecture also supports the
high-performance turbocharged 4B11T found in the Lancer Evolution X,
although this document focuses strictly on the naturally aspirated 4B11.
The engine is known for its durable construction, reduced frictional
losses, and balanced characteristics suitable for both urban commuting
and highway driving.
The Mitsubishi 4B11 has a total displacement of 1,998 cc (121.9 cubic
inches). The bore measures approximately 86 mm (3.39 inches), while the
stroke is similarly 86 mm (3.39 inches), forming a perfectly square
configuration optimized for balanced power and torque characteristics.
The compression ratio generally falls between 10.0:1 and 10.5:1
depending on vehicle model and regional calibration.
Power output ranges between 147 and 158
horsepower (110 to 118 kW) at about 6,000 rpm. Peak torque averages 197
to 200 Nm (145 to 148 lb-ft) delivered around 4,200 rpm. Idle speed is
maintained near 700 ± 50 rpm. The ECU sets fuel cut-off near 6,800 rpm,
and normal redline is approximately 6,500 rpm. The engine utilizes a
four-stroke cycle and employs an electronically controlled ignition and
fuel-injection system. Firing order is 1-3-4-2.
The 4B11 engine features an aluminum cylinder block with cast-in steel
cylinder liners for durability and consistent wear resistance. The use
of aluminum significantly reduces engine mass compared to earlier
cast-iron blocks. The block incorporates a semi-closed deck for improved
strength and heat dissipation.
The forged-steel crankshaft is fully counterweighted and supported by five main bearings to ensure smooth rotation. The block-s deep-skirt design increases rigidity and reduces vibrations transmitted to the chassis. Pistons are constructed of lightweight aluminum alloy with low-friction skirt coatings to minimize internal drag.
Each piston carries two compression rings and
one oil-control ring to maintain combustion sealing and reduce oil
consumption. High-strength forged steel connecting rods transport
combustion forces from the pistons to the crankshaft, and full-floating
wrist pins reduce friction while improving durability. The oil-passage
network is internally cast to ensure proper lubrication and rapid
warm-up of all moving components.
The cylinder head is made of lightweight aluminum alloy and supports a
dual overhead camshaft (DOHC) configuration with four valves per
cylinder, totaling sixteen valves. The camshafts operate through
low-friction bucket tappets. The head design incorporates Mitsubishi’s
MIVEC (Mitsubishi Innovative Valve timing Electronic Control) system,
which provides continuously variable timing on both intake and exhaust
camshafts.
This improves volumetric efficiency, reduces emissions, and enhances torque delivery throughout the rev range. The combustion chambers are compact and shaped for rapid flame propagation, improving thermal efficiency.
Intake ports are straight and optimized for increased air velocity, while exhaust ports are tuned to evacuate gases efficiently. The timing system utilizes a chain drive designed for long service life, eliminating scheduled timing-belt replacements. The head includes integrated coolant passages to regulate combustion temperature and prevent detonation.
| Fuel System |
The Mitsubishi 4B11 employs a sequential multi-point electronic fuel-injection system. Fuel is drawn from the tank by an electric pump and delivered through high-pressure lines to the fuel rail. Solenoid-operated injectors deliver precisely metered fuel directly into the intake ports, ensuring fine atomization and even cylinder distribution.
The ECU manages fuel injection duration, timing, and mixture based on input from the mass-airflow sensor, manifold-absolute-pressure sensor, throttle-position sensor, oxygen sensors, crank-angle sensor, and coolant-temperature sensor. A return-less fuel system minimizes evaporative emissions and stabilizes fuel pressure.
The recommended fuel octane rating is 95 RON (91 AKI). The system maintains a typical fuel pressure of around 350 kPa (51 psi). Efficient injector spray patterns contribute to clean combustion, strong throttle response, and reduced fuel consumption.
| Lubrication System |
The lubrication system is a fully pressurized wet-sump type utilizing a high-capacity trochoid oil pump driven by the crankshaft. Oil is drawn through a pickup screen and pushed through a full-flow spin-on filter before distributing to the main gallery. Lubrication targets include crankshaft bearings, connecting-rod journals, camshaft journals, timing components, and valve-train mechanisms.
Piston-cooling oil jets reduce crown temperatures, improving reliability under high-load operation. Oil capacity ranges from 4.2 to 4.5 liters (4.4 to 4.8 US quarts), depending on vehicle installation. Recommended oil viscosity includes SAE 0W-20 or 5W-30 synthetic formulations meeting API SN or higher standards.
Oil pressure averages 350 to 450 kPa (51 to 65 psi) at 3,000 rpm. The PCV (positive-crankcase ventilation) system reduces crankcase pressure, controls emissions, and ensures clean internal airflow.
| Cooling System |
The cooling system features a belt-driven water pump, aluminum cross-flow radiator, thermostat, electric cooling fan, expansion reservoir, and temperature sensors. Coolant circulates through engine jackets to absorb excess heat, then passes through the radiator for dissipation. The thermostat typically begins opening at around 82°C (180°F) and is fully open near 95°C (203°F).
Cooling system pressure ranges between 12 and 15 psi. Total coolant capacity averages 6.0 to 6.5 liters (6.3 to 6.9 US quarts). A standard 50/50 mixture of ethylene-glycol antifreeze and distilled water provides freeze and corrosion protection. Temperature sensors relay information to the ECU for fan operation and fuel adjustments. Proper cooling performance ensures stable operation under high-load, high-temperature environments.
| Intake and Exhaust Systems |
The intake system utilizes a molded composite manifold with long, tuned runners designed to maximize mid-range torque. The air-filter housing contains a dry paper element for effective filtration. The throttle body is electronically actuated for precise airflow control, supporting smooth idle and responsive acceleration.
The exhaust system includes a high-flow exhaust manifold that channels exhaust gases to a catalytic converter positioned close to the engine for rapid warm-up. Oxygen sensors upstream and downstream of the catalytic converter maintain optimal air-fuel ratios and monitor catalyst efficiency. The exhaust system is engineered to reduce backpressure while maintaining low noise output.
| Ignition and Electrical System |
The 4B11 uses a coil-on-plug ignition system for direct spark delivery to each cylinder. The ECU controls spark timing based on engine load, knock sensor feedback, rpm, and temperature. Spark plugs are long-life iridium units gapped at approximately 1.0 millimeter (0.039 inch).
The alternator outputs 85 to 100 amperes, providing reliable electrical power for engine management, accessories, and battery charging. The reduction-gear starter ensures consistent engine cranking even in cold climates. Electrical wiring and harnesses are protected with heat-resistant insulation for durability.
| Other Systems |
Additional systems integrated into the 4B11 include a PCV system for crankcase ventilation, EVAP for controlling fuel-vapor emissions, and EGR provisions depending on regional requirements. Various accessories driven by the serpentine belt include the alternator, air-conditioning compressor, and power-steering pump or electric steering system interfaces.
Engine mounts use hydraulic damping to reduce noise and vibration. Sensor networks throughout the engine supply the ECU with constant data for optimal operation.
| Dimensions and Weight |
The 4B11 maintains compact dimensions for its displacement. Overall length is around 650 mm (25.6 inches), width is about 630 mm (24.8 inches), and height measures near 680 mm (26.8 inches). Dry weight averages approximately 135 to 150 kg (298 to 331 lbs), depending on installed accessories. Lightweight construction improves vehicle handling, efficiency, and front-to-rear weight distribution.
| Maintenance Data |
Recommended oil and filter changes occur every 10,000 to 15,000 km (6,000 to 9,000 miles). Air filters should be replaced every 20,000 to 30,000 km (12,000 to 18,000 miles). Spark plugs generally last 80,000 to 100,000 km (50,000 to 62,000 miles). Coolant should be replaced every five years or 100,000 km (62,000 miles).
The timing chain requires no regular replacement but should be inspected at high mileage. Accessory drive belts should be inspected at each major service. Fuel injectors may require cleaning periodically depending on fuel quality.
| Tightening Torques |
Cylinder-head bolts require multi-stage tightening, beginning at 30 Nm (22 lb-ft), followed by additional angular phases. Main-bearing-cap bolts tighten to approximately 60-70 Nm (44-52 lb-ft). Connecting-rod bolts secure at about 35-40 Nm (26-30 lb-ft) plus angle tightening.
Spark plugs tighten to roughly 18-20 Nm (13-15 lb-ft). The oil-drain plug is torqued to about 35 Nm (26 lb-ft). Intake-manifold bolts tighten to around 22-25 Nm (16-18 lb-ft), while exhaust-manifold nuts require approximately 30 Nm (22 lb-ft).
| Vehicle Applications |
The Mitsubishi 4B11 engine was used extensively in the Mitsubishi Lancer, Lancer Sportback, and Outlander. It also appeared in regional models such as the Mitsubishi ASX and international derivatives produced by partner manufacturers.
Known for its balanced performance and durability, the 4B11 became one of Mitsubishi’s most widely used modern engines. Its efficient valvetrain and advanced electronic management made it a dependable choice for compact sedans and crossover SUVs in many global markets.
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