Hyundai G4CS Specifications
| Engine Model: Hyundai G4CS |
| Engine Type: 4-cycle inline 4-cylinder SOHC liquid-cooled gasoline |
| Total Displacement: 143.5 cu.in (2.35 L) |
| Rated Engine Power: 110-128 Hp (82-96 kW) at 6000 rpm |
| Fuel System Type: Downdraft carburetor or multi-point fuel injection |
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The Hyundai G4CS is a 2.4-liter inline-4 engine
belonging to the Sirius engine family. Developed under license from Mitsubishi
and based on the 4G64 architecture, the G4CS served as a "big-block" variant
within the series, emphasizing displacement and low-end torque. Produced from
the late 1980s through the early 2000s, it was engineered to provide robust
power delivery for larger passenger sedans, executive vehicles, and light
commercial vans.
The engine is characterized by its long-stroke design, which prioritizes pulling
power over high-rpm performance, and its use of a dual balancing shaft system to
mitigate the inherent vibrations of a large-displacement four-cylinder unit.
Engine Type: Inline 4-cylinder, 4-cycle, water-cooled, gasoline.
Displacement: 2,351 cc (143.5 cu.in).
Bore: 86.5 mm (3.41 in).
Stroke: 100.0 mm (3.94 in).
Compression Ratio: 8.5:1 (low-compression variants for carb or early MPI
systems).
Compression Ratio: 8.6:1 (common for later multi-point injection systems).
Valvetrain Configuration: Single Overhead Camshaft (SOHC).
Valves: 8-valve (2 valves per cylinder) for early and commercial variants.
Valves: 16-valve (4 valves per cylinder) for later passenger car models.
Firing Order: 1-3-4-2.
Maximum Power Output: 110-128 hp (82-96 kW) @ 4,500-5,000 rpm.
Maximum Torque Output: 181-193 Nm (133-142 lb-ft) @ 2,400-3,500 rpm.
The cylinder block is constructed from cast iron to
provide structural rigidity and durability under high torque loads. It features
a deep-skirt design for increased crankshaft support. The bore diameter is 86.5
mm (3.41 in).
The block is configured to accommodate dual
counter-rotating silent shafts (balancer shafts) driven by a separate
belt, which are mounted within the crankcase to cancel out secondary
vibrations generated by the engine’s long-stroke reciprocating mass.
The cylinder bores are precision-machined
without liners in the standard configuration, relying on the base iron
material. The crankshaft is forged steel, supported by five main
bearings.
The cylinder head is manufactured from aluminum alloy
to reduce overall engine weight. It utilizes a cross-flow design, with intake
and exhaust ports located on opposite sides of the head.
8-Valve Variant: Features a single camshaft operating two valves per cylinder
via rocker arms. Valve clearances are maintained by hydraulic lash adjusters
(HLAs) in most later production runs, eliminating the need for periodic manual
valve adjustments. Early 8-valve configurations utilized mechanical lash
adjusters requiring shim selection.
16-Valve Variant: Employs a SOHC design utilizing a roller rocker arm system to
actuate four valves per cylinder. This configuration incorporates hydraulic lash
adjusters as standard, ensuring silent operation and maintenance-free valve
train operation.
Valve Seat Angles: Intake and exhaust seats feature a multi-angle cut to
optimize flow efficiency. Valve Diameter (16-Valve): Intake valves are
approximately 35.0 mm (1.38 in); exhaust valves are approximately 31.0 mm (1.22
in).
The fuel delivery system varies based on production
year and vehicle application. Early Applications: Utilized a downdraft
carburetor system with a mechanical fuel pump mounted on the cylinder head.
Mainstream Production: Transitioned to an Electronic Multi-Point Injection (MPI)
system. This setup employs a sequential injection strategy where fuel injectors
are mounted in the intake manifold runners, firing directly toward the intake
valves.
The system is managed by an engine control unit
(ECU) utilizing inputs from a mass airflow sensor (or manifold absolute
pressure sensor), throttle position sensor, coolant temperature sensor,
and oxygen sensor to maintain a stoichiometric air-fuel ratio. Fuel
pressure in the MPI system is regulated to 2.9-3.3 bar (42-48 psi).
The lubrication system is a full-flow, pressurized type
utilizing a gear-type oil pump driven directly by the crankshaft.
Oil Pump Type: Rotor-type (internal gear) mounted to the front of the
crankshaft.
Oil Capacity: 4.3-4.5 liters (4.5-4.8 qt) including oil filter replacement.
Recommended Oil Viscosity: 10W-30 or 10W-40.
Oil Quality Requirement: API SG, SH, or SJ classification.
Oil Pressure: At idle (warm), pressure ranges from 0.5-1.0 bar (7-14 psi); at
3,000 rpm, pressure ranges from 3.0-4.0 bar (43-58 psi). Oil Pan: Stamped steel
construction with a baffle plate to maintain oil pickup during vehicle
acceleration and cornering.
The cooling system is a pressurized, forced circulation
type designed to maintain operating temperature stability under high load
conditions. Water Pump: Centrifugal type driven by the timing belt. System
Pressure: Radiator cap rated between 0.9-1.1 bar (13-16 psi).
Thermostat: Wax-pellet type, located in the coolant outlet housing. Opening
temperature ranges from 82-88 °C (180-190 °F). Coolant Capacity: 7.0-7.5 liters
(7.4-7.9 qt) inclusive of the engine block and heater core.
Radiator: Cross-flow type with a cooling fan configuration that varies by
application: engine-driven mechanical fan with a thermal clutch for commercial
vehicles; electric thermostatically controlled fan for passenger car
applications.
Ignition System: Distributor-type ignition in earlier
models, utilizing a crank-angle sensor within the distributor. Later MPI
applications employ a distributorless ignition system (DIS) with a three-coil
pack (waste-spark configuration) triggered by a crankshaft position sensor and
camshaft position sensor.
Timing System: Dual-belt configuration. The primary timing belt drives the
camshaft and the water pump. A secondary, smaller belt drives the dual silent
balancer shafts. The primary belt features automatic tensioner adjustment via a
spring-loaded tensioner pulley. Synchronization marks on the crankshaft
sprocket, camshaft sprocket, and balancer shaft sprockets must be aligned during
installation.
Balancer System: Two silent shafts (balancer shafts) rotate at twice the engine
speed. The left shaft (from front view) incorporates a weight to cancel primary
imbalances; the right shaft rotates in the opposite direction to cancel
secondary imbalances.
Exhaust System: Cast iron exhaust manifold with a single catalytic converter
(closed-loop feedback type for MPI systems). Oxygen sensor(s) located before and
after the catalyst for emissions monitoring.
Overall Length: 635 mm (25.0 in) from accessory drive
face to bellhousing mating surface.
Overall Width: 610 mm (24.0 in) measured across the valve cover and intake
manifold assembly.
Overall Height: 710 mm (28.0 in) from bottom of oil pan to top of valve cover.
Dry Weight: 140-150 kg (309-331 lb).
Valve Clearance (Hydraulic Lash Adjuster): No
adjustment required. For early mechanical lash adjuster variants (8-valve):
Intake 0.15 mm (0.006 in) cold; Exhaust 0.25 mm (0.010 in) cold. Timing Belt
Replacement Interval: 96,000 km (60,000 miles) or 5 years, whichever occurs
first. The balancer shaft belt must be replaced concurrently.
Spark Plug Type: NGK BPR5ES or equivalent (MPI); NGK BPR6ES for carbureted
applications. Spark Plug Gap: 1.0-1.1 mm (0.039-0.043 in). Spark Plug Torque:
25-30 Nm (18-22 lb-ft). Drive Belt Tension (Accessory): 7-9 mm (0.28-0.35 in)
deflection under 10 kg (22 lb) of force at the midpoint of the longest span.
Coolant Change Interval: 48,000 km (30,000 miles) or 2 years. Engine Oil Change
Interval: 5,000-7,500 km (3,000-4,700 miles) depending on operating conditions.
Idle Speed (MPI, neutral): 750 ± 50 rpm. Ignition Timing (MPI, base): 5°-10°
BTDC at idle with test terminal grounded.
Cylinder Head Bolts (8-valve), Step 1: 30 Nm (22
lb-ft).
Cylinder Head Bolts (8-valve), Step 2: 70 Nm (52 lb-ft).
Cylinder Head Bolts (16-valve), Step 1: 30 Nm (22 lb-ft).
Cylinder Head Bolts (16-valve), Step 2: 65 Nm (48 lb-ft).
Main Bearing Cap Bolts: 60-65 Nm (44-48 lb-ft).
Connecting Rod Cap Nuts: 45-50 Nm (33-37 lb-ft).
Camshaft Bearing Cap Bolts (SOHC): 20-25 Nm (15-18 lb-ft).
Intake Manifold Nuts/Bolts: 20-25 Nm (15-18 lb-ft).
Exhaust Manifold Nuts: 30-35 Nm (22-26 lb-ft).
Valve Cover Nuts/Bolts: 5-8 Nm (4-6 lb-ft).
Oil Pan Bolts: 10-12 Nm (7-9 lb-ft).
Flywheel / Drive Plate Bolts: 110-120 Nm (81-89 lb-ft).
Water Pump Bolts: 20-25 Nm (15-18 lb-ft).
Timing Belt Tensioner Bolt: 25-30 Nm (18-22 lb-ft).
Spark Plugs: 25-30 Nm (18-22 lb-ft).
Hyundai Sonata (Y2 / Y3): 1988-1998 model years.
Utilized in both 8-valve and 16-valve SOHC configurations with MPI.
Hyundai Grandeur (L Generation): Used as the base powerplant for the executive
sedan lineup, replacing the Mitsubishi-sourced V6 in some markets.
Hyundai H-1 / Starex / H100: 1997-2004 (and subsequent variants in certain
markets). Installed in both passenger vans and light-duty commercial trucks,
often with a carburetor or MPI depending on regional emissions standards.
Hyundai Santamo: The G4CS served as the highest displacement option for this
mid-sized multi-purpose vehicle (MPV).
Hyundai Grace (late variants): Applied in commercial van configurations
requiring high low-end torque for load carrying.
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