Isuzu G180Z Specifications
| Engine Model: Isuzu G180Z |
| Engine Type: 4-stroke in-line 4-cylinder 8-valve SOHC liquid-cooled gasoline |
| Total Displacement: 110.9 cu.in (1.82 L) |
| Rated Engine Power: 80-110 Hp (60-82 kW) at 5400 rpm |
| Fuel System Type: Carburetor |
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The Isuzu G180Z is a 1.8-liter, inline-four,
naturally aspirated gasoline engine from the G-Z series, a family of
powerplants developed by Isuzu throughout the 1970s and 1980s. The Z
designation indicates a performance-oriented or higher-output variant
within the G engine lineage. This engine was widely applied across
Isuzu’s passenger car, light truck, and sport utility vehicle range. It
served as the high-performance option for the Gemini and as the standard
powerplant for the LUV pickup and early Trooper (Bighorn) models,
establishing a reputation for durability and mechanical simplicity.
The G180Z is characterized by its cast iron cylinder block, aluminum
alloy cylinder head, single overhead camshaft (SOHC) valvetrain with
eight valves, and a dual-row timing chain - a durable alternative to
belt-driven systems found on contemporary engines. The hemispherical
combustion chamber design and nearly square bore and stroke ratio
provide a balanced power delivery. Fuel delivery is managed by a
two-barrel Hitachi carburetor. The engine’s robust five-main-bearing
crankshaft and timing chain construction contribute to its longevity,
while the aluminum head requires proper cooling system maintenance to
prevent head gasket failure.
The G180Z is a four-stroke, water-cooled, naturally aspirated
inline-four gasoline engine configured for longitudinal mounting in
rear-wheel-drive and four-wheel-drive vehicle architectures. Its square
bore and stroke ratio provides a balance of low-end torque and high-rpm
power.
Engine Type: Inline-4, 4-cycle, water-cooled, naturally aspirated
Displacement: 1,817 cc (110.9 cu.in)
Bore and Stroke: 84.0 mm (3.31 in) x 82.0 mm (3.23 in)
Compression Ratio: 8.5:1 (standard) to 9.2:1 (high-compression variants)
Valvetrain: SOHC, 8-valve (2 valves per cylinder) with chain drive
Fuel System: Hitachi two-barrel downdraft carburetor
Firing Order: 1-3-4-2
Ignition Timing: 6° before top dead center at 800-900 rpm
Maximum Power: 60-82 kW (80-110 hp) depending on market
Maximum Torque: 135-145 Nm (100-107 lb-ft) at 3,000-3,400 rpm
Redline: 6,000 rpm
The cylinder block is manufactured from high-strength gray cast iron, a
material selected for its durability, wear resistance, and
vibration-damping properties. The block features a closed-deck design,
with the cylinder bores fully enclosed by the water jacket structure at
the top deck surface. Cast-in-place cylinder bores are machined directly
into the iron casting.
The block incorporates a deep-skirt design extending below the
crankshaft centerline, providing robust support for the five main
bearing caps. The main bearing caps are cast iron with a two-bolt
configuration. The block is configured for longitudinal mounting with
engine mount brackets positioned for rear-wheel-drive vehicle
architectures. A stamped steel oil pan is sealed to the lower crankcase.
Block Material: Cast iron
Bore Diameter: 84.0 mm (3.31 in)
Main Bearing Caps: Cast iron, two-bolt design with five main bearings
The cylinder head is constructed from aluminum alloy to reduce overall
engine mass and improve heat dissipation. The head utilizes a cross-flow
design with the intake manifold on one side and the exhaust manifold on
the opposite side. The hemispherical combustion chamber design promotes
efficient flame propagation and allows for larger valve diameters than
wedge-style chambers.
The SOHC valvetrain operates eight valves - two per cylinder - via
rocker arms. A defining feature of the G180Z is the dual-row timing
chain, which drives the camshaft from the crankshaft sprocket. A
hydraulic chain tensioner maintains optimal chain tension. The timing
chain design provides greater durability than belt-driven systems. Valve
clearance is set manually using adjustment screws on the rocker arms, a
system requiring periodic maintenance. Hydraulic lash adjusters are not
used.
Head Material: Aluminum alloy
Combustion Chamber Type: Hemispherical
Valve Configuration: SOHC, 2 valves per cylinder with rocker arms
Valve Diameter (Intake): 39.0 mm (1.54 in)
Valve Diameter (Exhaust): 34.0 mm (1.34 in)
Valve Stem Diameter: 8.0 mm (0.31 in)
Valve Seat Angle: 45 degrees
Valve Clearance (Hot, Intake): 0.15 mm (0.006 in)
Valve Clearance (Hot, Exhaust): 0.25 mm (0.010 in)
The G180Z employs a carbureted fuel system centered around a Hitachi
two-barrel downdraft carburetor. The carburetor incorporates a primary
and secondary barrel, with the secondary barrel opening under heavy
throttle demand. A mechanical fuel pump, driven by the camshaft, draws
fuel from the tank and delivers it to the carburetor float chamber.
The carburetor includes a choke system for cold-start enrichment, an
accelerator pump for transient throttle response, and an idle circuit
for stable low-speed operation. A fuel filter is mounted in the fuel
supply line to remove contaminants. The intake manifold is a cast
aluminum design with provisions for the carburetor mounting flange and
coolant heating passages to improve fuel vaporization in cold
conditions.
Fuel System: Hitachi two-barrel downdraft carburetor
Carburetor Type: DCR-328 or equivalent depending on application
Choke System: Automatic (thermostat-controlled) or manual depending on
market
Fuel Pump: Mechanical, camshaft-driven
Fuel Requirement: 87 octane or higher (91 for high-compression variants)
The lubrication system is a fully pressurized, wet-sump design utilizing
a gear-type oil pump mounted to the front of the crankshaft. The oil
pump draws lubricant from a stamped steel oil pan through a mesh
strainer and circulates it through a full-flow, replaceable oil filter
before entering the main oil gallery. From the gallery, pressurized oil
is distributed to the crankshaft main bearings, connecting rod bearings,
camshaft bearings, and timing chain tensioner.
A pressure relief valve integrated into the oil pump maintains system
pressure within operational limits to prevent over-pressurization during
cold starts or high engine speeds. The oil pan incorporates a baffle to
maintain oil pickup during cornering and acceleration.
Oil Type: SAE 10W-30, 10W-40, or 20W-50 (API SF, SG, or higher)
Oil Capacity (with filter): 4.0 liters (4.2 US qt)
Oil Pressure (at 3,000 rpm): 294-392 kPa (42.6-56.9 psi)
Oil Pressure (at idle): 98 kPa (14.2 psi) minimum
Oil Pump Type: Gear-type, crankshaft-driven
The cooling system is a pressurized, liquid-cooled design employing a
cross-flow copper or aluminum radiator with a mechanical fan. A
centrifugal-type water pump, driven by the accessory belt, circulates
coolant through the cylinder block, cylinder head, and heater core.
A wax-pellet thermostat regulates coolant flow to maintain optimal
operating temperature, with a bypass circuit that allows the engine to
warm rapidly. The system is designed to provide uniform cooling across
all four cylinders. A coolant recovery tank is integrated on later
applications to maintain system pressure. The aluminum cylinder head
requires proper coolant maintenance to prevent galvanic corrosion and
head gasket failure.
Coolant Type: Ethylene-glycol based antifreeze with corrosion inhibitors
Coolant Capacity: 6.0-7.0 liters (6.3-7.4 US qt)
Thermostat Opening Temperature: 82-86 °C (180-187 °F)
Thermostat Full-Open Temperature: 95 °C (203 °F)
Radiator Cap Pressure: 88-108 kPa (12.8-15.7 psi)
Water Pump Type: Centrifugal, belt-driven
| Intake and Exhaust Systems |
Intake System: Air is drawn through a dry-type paper element air filter
before entering the Hitachi carburetor. The intake manifold is a cast
aluminum design with coolant passages for cold-start enrichment.
Exhaust System: Cast iron exhaust manifold with individual runners
collecting into a single downpipe.
Ignition System: Distributor-based ignition system with a
crankshaft-driven or camshaft-driven distributor. The distributor houses
the ignition points on early variants with a mechanical advance
mechanism, while later variants utilize a breakerless electronic
ignition system. A vacuum advance unit adjusts ignition timing based on
engine load.
Timing Drive: A dual-row timing chain (later variants use a single-row
chain) connects the crankshaft sprocket to the camshaft sprocket. A
hydraulic chain tensioner maintains optimal chain tension. The plastic
chain guides are service items that can become brittle with age.
Overall Length: 600 mm (23.6 in)
Overall Width: 580 mm (22.8 in)
Overall Height: 670 mm (26.4 in)
Dry Weight (complete engine): 120 kg (265 lb)
Oil Change Interval: 5,000 km (3,000 mi) under normal driving
conditions.
Oil Filter Change: At every oil change.
Timing Chain: Inspection every 100,000 km (60,000 mi).
Engine Coolant Replacement: 40,000 km (25,000 mi) or 2 years.
Spark Plug Replacement: 20,000 km (12,000 mi) for standard plugs.
Spark Plug Type: NGK BP6ES or equivalent
Spark Plug Gap: 0.7-0.8 mm (0.028-0.031 in)
Drive Belt (Accessory) Inspection: Every 10,000 km (6,000 mi) for
tension, cracking.
Air Filter Replacement: 20,000 km (12,000 mi) or as indicated by
inspection.
Fuel Filter Replacement: 20,000 km (12,000 mi) for external filter
types.
Intake Valve Clearance: 0.15 mm (0.006 in) hot.
Exhaust Valve Clearance: 0.25 mm (0.010 in) hot.
Valve Clearance Adjustment: Inspect and adjust every 20,000 km (12,000
mi).
Idle Speed Adjustment: 800-900 rpm with no electrical or accessory load.
Cylinder Head Bolts (M10 x 1.25), 1st pass: 20 Nm (15 lb-ft).
Cylinder Head Bolts (M10 x 1.25), 2nd pass: 50 Nm (37 lb-ft).
Cylinder Head Bolts (M10 x 1.25), final pass: 70 Nm (52 lb-ft).
Main Bearing Cap Bolts (M10 x 1.25): 45-50 Nm (33-37 lb-ft).
Connecting Rod Cap Bolts (M9 x 1.0): 35-40 Nm (26-30 lb-ft).
Camshaft Bearing Cap Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Rocker Arm Shaft Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Intake Manifold Bolts (M8 x 1.25): 16-20 Nm (12-15 lb-ft).
Exhaust Manifold Nuts (M8 x 1.25): 16-20 Nm (12-15 lb-ft).
Spark Plugs: 18-22 Nm (13-16 lb-ft).
Oil Pan Bolts (M6 x 1.0): 8-10 Nm (71-89 lb-in).
Water Pump Bolts (M8 x 1.25): 18-22 Nm (13-16 lb-ft).
Crankshaft Pulley Bolt (M14 x 1.5): 100-120 Nm (74-89 lb-ft).
Flywheel / Drive Plate Bolts (M10 x 1.25): 60-65 Nm (44-48 lb-ft).
The Isuzu G180Z engine was utilized across Isuzu’s passenger car, light
truck, and sport utility vehicle range throughout the 1970s and 1980s,
serving as both a performance option and standard powerplant.
Isuzu Gemini (PF60): 1.8-liter ZZ, LS, and performance variants.
Isuzu LUV / Chevy LUV: Primary engine for light pickup applications.
Isuzu Trooper / Bighorn (UBS13): Early 1980s 1.8-liter variants.
Holden Gemini (ZZ/Z): Performance variant and limited edition models.
Isuzu 117 Coupe: Mid-range 1.8-liter models.
Isuzu KB: Commercial pickup variants in select markets.
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