Mitsubishi G63B Specifications
| Engine Model: Mitsubishi G63B |
| Engine Type: 4-cycle inline 4-cylinder SOHC liquid-cooled gasoline |
| Total Displacement: 122 cu.in (1.99 L) |
| Rated Engine Power: 90-177 Hp (66-132 kW) at 5500 rpm |
| Fuel System Type: Carburetor or multi-point fuel injection |
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The Mitsubishi G63B is a 2.0-liter inline-four gasoline
engine from the Sirius (4G6) family, serving as the SOHC predecessor to the
legendary DOHC 4G63 powerplant that later propelled the Lancer Evolution to
international acclaim. Introduced in the early 1980s, the G63B represented a
significant advancement in Mitsubishi’s four-cylinder engine technology,
incorporating the company’s Silent Shaft balancing system to reduce secondary
vibrations inherent in inline-four configurations. Produced in both naturally
aspirated and turbocharged forms, the engine powered a diverse range of vehicles
from the Starion sports coupe to the L200 pickup and the Galant sedan.
The G63B utilized an aluminum cylinder head with either 8-valve or 12-valve
configurations, the latter incorporating the MCA-Jet system with auxiliary jet
valves designed to improve combustion efficiency and emissions performance. The
engine’s robust cast iron block, belt-driven timing system, and provision for
forced induction established the foundation for the high-performance variants
that defined Mitsubishi’s turbocharged era.
Engine Type: 4-stroke, inline 4-cylinder, water-cooled gasoline engine.
Displacement: 1,997 cc (2.0 L; 122 cu.in).
Bore: 85.0 mm (3.346 in).
Stroke: 88.0 mm (3.465 in).
Firing Order: 1-3-4-2.
Valvetrain: SOHC (single overhead camshaft), timing belt drive, 2 or 3 valves
per cylinder depending on MCA-Jet configuration.
Combustion Chamber: Hemispherical with cross-flow port arrangement.
Aspiration: Naturally aspirated or single turbocharger with electronic control
injection (ECI-Turbo).
Compression Ratio
Naturally aspirated (carburetor): 8.5:1-9.5:1.
Naturally aspirated (EFI): 9.0:1-9.5:1.
Turbocharged (ECI-Turbo): 7.5:1-8.5:1.
SOHC 8-Valve Naturally Aspirated (Carburetor)
Maximum Power: 66-77 kW (90-103 hp) at 5,000-5,500 rpm.
Maximum Torque: 155-165 Nm (114-122 lb-ft) at 3,000-3,500 rpm.
SOHC 8-Valve Naturally Aspirated (ECI Multi-point
Fuel Injection)
Maximum Power: 81-85 kW (109-114 hp) at 5,500 rpm.
Maximum Torque: 165-172 Nm (122-127 lb-ft) at 3,500 rpm.
SOHC 12-Valve MCA-Jet Naturally Aspirated
(Carburetor or EFI)
Maximum Power: 78-86 kW (105-115 hp) at 5,500 rpm.
Maximum Torque: 165-175 Nm (122-129 lb-ft) at 3,500 rpm.
SOHC 12-Valve Turbocharged (ECI-Turbo)
Maximum Power: 108-127 kW (145-170 hp) at 5,000-5,500 rpm.
Maximum Torque: 210-245 Nm (155-181 lb-ft) at 2,500-3,500 rpm.
High-Output Turbocharged (Starion, Intercooled)
Maximum Power: 132-147 kW (177-197 hp) at 5,500 rpm.
Maximum Torque: 265-275 Nm (195-203 lb-ft) at 3,500 rpm.
Compression Pressure
Standard: 1.35-1.55 MPa (196-225 psi).
Minimum service limit: 1.20 MPa (174 psi).
Maximum permissible variation between cylinders: 0.10 MPa (15 psi).
The cylinder block is constructed from high-strength
gray cast iron with a closed-deck design, providing exceptional rigidity for the
reciprocating assembly. The block incorporates the Silent Shaft system, with two
counter-rotating balance shafts positioned within the block on either side of
the crankshaft centerline. These shafts, driven by a separate small toothed belt
from the crankshaft, rotate at twice engine speed to cancel the secondary
harmonic vibrations inherent to inline-four engines.
The block features five main bearings supporting the forged steel crankshaft,
with bearing caps secured by vertical bolts. Cylinders are cast directly into
the block without replaceable liners, finished with a plateau honing pattern.
The water jacket surrounds the cylinders for the full depth of the stroke, with
coolant passages extending upward into the cylinder head. The block includes
cast bosses for engine mounting brackets and provisions for the balance shaft
housing on the right side.
The cylinder head is manufactured from aluminum alloy
with a cross-flow design positioning intake ports on the left side and exhaust
ports on the right side for transverse engine mounting. The single overhead
camshaft is supported by five bearing journals and actuates the valves through
steel rocker arms with adjustable screw-and-locknut mechanisms. The MCA-Jet
(Mitsubishi Clean Air) system, present on 12-valve heads, incorporates a small
auxiliary jet valve positioned adjacent to each intake valve. This jet valve
introduces an additional swirl-inducing airflow path to promote more complete
combustion and reduce hydrocarbon emissions. The jet valves are actuated by the
same rocker arm assembly and require independent clearance adjustment.
Valve Data (8-Valve Head)
Number of Valves: 8 total (2 per cylinder).
Intake Valve Diameter: 44.0 mm (1.732 in).
Exhaust Valve Diameter: 37.0 mm (1.457 in).
Valve Stem Diameter: 8.0 mm (0.315 in) for both intake and exhaust.
Valve Data (12-Valve MCA-Jet Head)
Number of Valves: 12 total (3 per cylinder: 2 intake, 1 exhaust, plus 1 jet
valve per cylinder).
Intake Valve Diameter: 41.0 mm (1.614 in).
Jet Valve Diameter: 8.0 mm (0.315 in).
Exhaust Valve Diameter: 35.0 mm (1.378 in).
Valve Stem Diameter: Intake and exhaust: 8.0 mm (0.315 in); jet valve: 6.0 mm
(0.236 in).
Valve Seat Inserts: Induction-hardened seats machined directly into the cylinder
head for intake valves; heat-resistant alloy steel inserts for exhaust valves.
Valve Clearance (hot engine, at operating
temperature)
Intake Valve: 0.15 mm (0.006 in)
Exhaust Valve: 0.25 mm (0.010 in)
Jet Valve (MCA-Jet heads): 0.25 mm (0.010 in)
The G63B was produced with three distinct fuel system
configurations. Early naturally aspirated variants employed a dual-throat
downdraft carburetor with mechanical choke. Later naturally aspirated variants
utilized ECI (Electronic Control Injection) multi-point fuel injection with
sequential or semi-sequential injection timing.
Turbocharged variants employed ECI-Turbo, a
multi-point fuel injection system with a dedicated engine control unit
that managed fuel delivery based on manifold absolute pressure, intake
air temperature, and engine speed. The turbocharged system included a
fuel pressure regulator referenced to manifold pressure to maintain a
constant pressure differential across the injectors under boost
conditions.
Injectors (EFI variants): Side-feed, high-impedance; naturally
aspirated: 180-210 cc/min at 300 kPa; turbocharged: 240-290 cc/min at
300 kPa. Fuel Filtration: In-line replaceable filter rated at 10-15
microns; carbureted variants use filter at fuel pump inlet. Fuel
Pressure (EFI naturally aspirated): 280-320 kPa (41-46 psi). Fuel
Pressure (ECI-Turbo): 250-280 kPa (36-41 psi) at idle; rises
proportionally with manifold pressure under boost. Fuel Specification:
Regular unleaded 91 RON minimum for naturally aspirated; premium
unleaded 95 RON minimum for turbocharged variants.
The lubrication system employs a gear-type oil pump
mounted within the front timing case and driven by the crankshaft. The pump
draws oil from a baffled steel sump through a strainer screen and delivers it to
a full-flow disposable cartridge oil filter mounted on the cylinder block. The
system incorporates a pressure relief valve calibrated to maintain stable
pressure across the operating range.
Main galleries distribute oil to the crankshaft main bearings, connecting rod
bearings, camshaft bearings, rocker arm assembly, and balance shaft bearings.
Turbocharged variants incorporate a water-cooled oil cooler mounted between the
oil filter and the block, using engine coolant to maintain oil temperature under
sustained boost conditions.
Oil Pump Type: Gear-type, crankshaft-driven.
Oil Pressure (hot, at 3,000 rpm): 300-400 kPa (44-58 psi).
Oil Pressure (hot, idle): 50 kPa (7 psi) minimum.
Oil Capacity (with filter, standard sump): 4.0 L (4.2 US qt).
Oil Capacity (with filter, turbocharged with oil cooler): 4.3 L (4.5 US qt).
Oil Specification: API SF, SG, SH, or higher; SAE 10W-30 or 10W-40 for most
climates; SAE 20W-50 for sustained high ambient temperatures above 30 °C (86
°F).
The cooling system employs a belt-driven centrifugal
water pump mounted to the front of the cylinder block. Coolant flows from the
radiator through the pump, then through the cylinder block water jacket, upward
into the cylinder head, and returns to the radiator through a thermostat
housing. A wax-pellet thermostat with a bypass circuit maintains operating
temperature stability. The system incorporates a cross-flow radiator with a
pressure-type filler cap rated at 75-95 kPa (11-14 psi). Turbocharged variants
include an additional coolant circuit to the turbocharger bearing housing, with
coolant circulating after engine shutdown through natural convection to prevent
oil coking.
Water Pump Type: Belt-driven centrifugal pump with cast iron housing and stamped
steel impeller. Coolant Capacity (engine and radiator): 6.0-7.0 L (6.3-7.4 US
qt) depending on heater core and oil cooler configuration. Thermostat Opening
Temperature: 82 °C (180 °F) for naturally aspirated; 76 °C (169 °F) for
turbocharged. Thermostat Fully Open Temperature: 95 °C (203 °F). Coolant
Specification: Ethylene-glycol based with aluminum-compatible corrosion
inhibitors; 30-50% concentration.
| Intake and Exhaust Systems |
Intake System: Naturally aspirated variants utilize a
cast aluminum intake manifold with either carburetor flange or fuel injector
bosses. Turbocharged variants incorporate a cast iron exhaust manifold with an
integral mounting flange for the Mitsubishi TD04 or TD05 turbocharger. The
intake system on turbocharged engines includes a plastic or aluminum intake
manifold with provisions for the blow-off valve and boost pressure sensing.
Intercooled variants, present on high-output Starion and certain export models,
utilize a water-to-air or air-to-air charge cooler mounted between the
turbocharger compressor outlet and the throttle body.
Exhaust System: Cast iron exhaust manifold with a single outlet for naturally
aspirated variants; turbocharged variants use a manifold designed to mount the
turbocharger directly to the exhaust flange. The system incorporates a catalytic
converter on all emissions-controlled markets.
| Ignition and Electrical System |
Ignition System: Distributor-type ignition with
mechanical and vacuum advance on carbureted variants. EFI variants utilize a
distributor with electronic advance controlled by the engine control unit.
Turbocharged variants incorporate a knock sensor to permit ignition timing
advance under high-load conditions while preventing detonation. Spark plugs are
copper-core resistor type with a gap dependent on induction system. Spark Plug
Gap: Naturally aspirated: 1.0-1.1 mm (0.039-0.043 in); turbocharged: 0.7-0.8 mm
(0.028-0.031 in).
Electrical System: 12 V negative-ground electrical architecture. Starter motor
is a reduction-gear type mounted to the transmission bellhousing. Alternator
output ranges from 55 A to 90 A depending on vehicle specification.
Silent Shaft System: Two balance shafts are housed
within the cylinder block, driven by a separate small toothed belt from the
crankshaft. The shafts rotate in opposite directions at twice crankshaft speed
to cancel the vertical secondary vibration inherent to inline-four engines. The
system requires precise timing alignment during installation; incorrect
alignment produces objectionable vibration at cruising speeds. The small balance
shaft belt is a critical service item; failure can result in belt debris
interfering with the main timing belt, causing valve-to-piston contact.
Length (front of timing cover to rear of flywheel
housing): 570 mm (22.4 in).
Width (overall, including intake and exhaust manifolds): 590 mm (23.2 in).
Height (from oil pan rail to top of valve cover): 680 mm (26.8 in).
Dry Weight (naturally aspirated, complete engine with flywheel): 140 kg (309
lb).
Dry Weight (turbocharged, with turbocharger and manifolds): 150 kg (331 lb).
Engine Oil: API SF, SG, SH, or higher; SAE 10W-30 or
10W-40 for general use; SAE 20W-50 for ambient temperatures consistently above
30 °C (86 °F). Oil Change Interval: 5,000 km (3,000 mi) for severe service;
7,500 km (4,700 mi) for normal highway operation. Oil Filter Replacement: Every
oil change. Coolant Capacity: 6.0-7.0 L (6.3-7.4 US qt). Coolant Change
Interval: 24 months or 40,000 km (25,000 mi).
Fuel Filter Replacement: 20,000 km (12,000 mi). Air Filter Replacement: 20,000
km (12,000 mi); more frequent under dusty conditions. Timing Belt Replacement:
60,000 km (37,000 mi) for early variants; 100,000 km (62,000 mi) for later
variants; interference engine, failure results in piston-to-valve contact.
Balance Shaft Belt Replacement: 60,000 km (37,000 mi); to be replaced
concurrently with timing belt.
Valve Clearance Inspection: 20,000 km (12,000 mi); adjustment using
screw-and-locknut mechanism required if clearance exceeds specification. Spark
Plug Replacement: 20,000 km (12,000 mi) for copper-core; 60,000 km (37,000 mi)
for platinum where equipped. Idle Speed (carburetor, manual transmission,
neutral): 750-800 rpm. Idle Speed (EFI, manual transmission, neutral): 700-750
rpm. Jet Valve Inspection (MCA-Jet heads): 20,000 km (12,000 mi); clearance
adjustment essential to prevent rough idle and increased emissions.
Cylinder Head Bolts (M11), Stage 1: 30 Nm (22 lb-ft)
Cylinder Head Bolts (M11), Stage 2: 60 Nm (44 lb-ft)
Cylinder Head Bolts (M11), Stage 3: 90 Nm (66 lb-ft); Stage 4: +90°
Main Bearing Cap Bolts (M12), Stage 1: 40 Nm (30 lb-ft)
Main Bearing Cap Bolts (M12), Stage 2: 70 Nm (52 lb-ft) +90°
Connecting Rod Cap Bolts (M9): 45-50 Nm (33-37 lb-ft)
Flywheel / Flexplate Bolts (M12): 130-140 Nm (96-103 lb-ft)
Camshaft Bearing Caps (M8): 20-25 Nm (15-18 lb-ft)
Camshaft Sprocket Bolt (M12): 80-90 Nm (59-66 lb-ft)
Balance Shaft Sprocket Bolts: 40-45 Nm (30-33 lb-ft)
Intake Manifold Bolts (M8): 15-20 Nm (11-15 lb-ft)
Exhaust Manifold Bolts (M10): 35-40 Nm (26-30 lb-ft)
Turbocharger to Exhaust Manifold (M10): 40-45 Nm (30-33 lb-ft)
Valve Cover Nuts (M6): 5-7 Nm (4-5 lb-ft)
Oil Pan Bolts (M6): 8-10 Nm (6-7 lb-ft)
Water Pump Bolts (M8): 15-20 Nm (11-15 lb-ft)
Thermostat Housing Bolts (M8): 15-20 Nm (11-15 lb-ft)
Spark Plugs: 25-30 Nm (18-22 lb-ft)
Engine Mount Bracket to Block (M10): 45-55 Nm (33-41 lb-ft)
Crankshaft Pulley Bolt (M14): 180-200 Nm (133-148 lb-ft)
Alternator Mounting Bolts (M10): 40-45 Nm (30-33 lb-ft)
Starter Motor Mounting Bolts (M10): 40-45 Nm (30-33 lb-ft)
Balance Shaft Tensioner Bracket: 20-25 Nm (15-18 lb-ft)
Mitsubishi Starion: A183, A184 series (1982-1989) with
G63B turbocharged in 8-valve and 12-valve configurations; intercooled variants
from 1985 onward. Mitsubishi Galant: E12A, E15A series (1980-1987) with
naturally aspirated G63B in 8-valve and 12-valve forms; ECI-Turbo variants in VR
and VR-4 models. Mitsubishi Lancer EX: A170, A172 series (1980-1987) with G63B
turbocharged in 2000 Turbo and 2000 Turbo Intercooler models. Mitsubishi Cordia:
A210 series (1982-1988) with G63B turbocharged in VR and GSR variants.
Mitsubishi Tredia: A210 series (1982-1988) with G63B turbocharged in VR and GSR
variants. Mitsubishi L200 / Mighty Max: Second generation (1982-1996) with
naturally aspirated G63B in pickup applications. Mitsubishi Pajero / Montero:
First generation (1982-1990) where the 2.0 L engine was specified in certain
markets as the base gasoline powerplant. Mitsubishi Delica / Starwagon: L300
series (1982-1994) with naturally aspirated G63B in gasoline-powered van
variants.
Dodge Conquest / Plymouth Conquest: Rebadged Mitsubishi Starion for North
American market with G63B turbocharged. Dodge Ram 50: Rebadged Mitsubishi L200
for North American market with naturally aspirated G63B. Hyundai Stellar:
Selected export markets utilizing the G63B under license.
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