Isuzu RZ4E-TC Specifications
| Engine Model: Isuzu RZ4E-TC |
| Engine Type: 4-stroke inline 4-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 115.8 cu.in (1.89 L) |
| Rated Engine Power: 150 Hp (115 kW) at 3600 rpm |
| Fuel System Type: Common Rail Direct Injection |
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The Isuzu RZ4E-TC, part of the Blue Power
series, is a 1.9-liter, four-cylinder diesel engine launched as a
high-efficiency replacement for the 2.5-liter 4JK1. This engine serves
as the primary powerplant for modern Isuzu D-Max and MU-X models,
focusing on weight reduction and low friction. The engine architecture
employs a double overhead camshaft (DOHC) design with four valves per
cylinder.
A variable geometry system (VGS) turbocharger with an intercooler
provides forced induction across a wide rpm range. The RZ4E-TC achieves
high-pressure common rail injection operating at 200 MPa (29,000 psi)
for precise fuel metering. Known for a mass reduction of 60 kg compared
to its predecessor, this engine incorporates diamond-like carbon (DLC)
coatings on injector needles and graphite-coated piston skirts to
maximize mechanical efficiency. Acoustic treatment includes a rigid
cylinder block and optimized timing chain geometry to reduce diesel
clatter and vibration significantly.
The Isuzu RZ4E-TC is a four-cycle, turbocharged and intercooled,
inline-four diesel engine. The cylinder arrangement is vertical,
in-line. The bore measures 80.0 mm (3.15 in) and the stroke is 94.4 mm
(3.72 in), resulting in a total displacement of 1,898 cc (115.8 cu.in).
The compression ratio is 16.5:1. The firing order is 1-3-4-2. Rotation
is clockwise when viewed from the front pulley end. The combustion
system is direct injection with a centrally located injector per
cylinder.
Rated speed for peak power is 3,600 rpm. Maximum power output is 110 kW
(150 hp) at 3,600 rpm. Peak torque is 350 Nm (258 lb-ft) available
across a plateau from 1,800 to 2,600 rpm. The governor is electronic,
integrated into the Engine Control Unit (ECU). Low idle speed is 750-800
rpm. The engine meets Euro 4, Euro 5, or Euro 6 emission standards
depending on the target market and model year.
The cylinder block is constructed from high-strength cast gray iron with
a deep-skirt design for enhanced rigidity under high cylinder pressures.
The cylinders are integrally cast into the block; no replaceable wet
sleeves are used in this engine. The parent bore finish features a
plateau honing process for reduced oil consumption and improved ring
seating. The crankcase incorporates five main bearing supports for the
crankshaft, a provision for the inline-four layout.
The main bearing caps are secured with four bolts each, consisting of
two vertical and two horizontal cross-bolts for increased rigidity and
reduced bore distortion. A ladder frame is integrated into the lower
crankcase structure, enhancing stiffness and reducing noise radiation. A
structural aluminum oil pan contributes to weight reduction while
providing rigidity. The block incorporates a side-mounted oil filter
housing and an integrated oil cooler mounting face.
0The cylinder head is a single, lightweight aluminum alloy casting
spanning the entire length of the four cylinders. The valvetrain uses a
double overhead camshaft (DOHC) configuration with roller finger
followers, operating four valves per cylinder for a total of 16 valves.
The dual camshafts are driven by a maintenance-free timing chain. A
single-stage timing chain connects the crankshaft sprocket to a
jackshaft, which drives the exhaust camshaft sprocket; a secondary chain
connects the exhaust camshaft to the intake camshaft.
The intake camshaft incorporates a variable valve timing (VVT) phaser
for optimized intake valve timing across the engine speed range. The
valves are arranged in a cross-flow pattern: two intake and two exhaust
valves per cylinder. Intake valve diameter is 30.0 mm (1.18 in); exhaust
valve diameter is 26.0 mm (1.02 in). The valve stem seals are
positive-type with fluorocarbon rubber.
The combustion chamber is a re-entrant bowl design machined directly
into the piston crown, with the cylinder head providing a flat mating
surface. The valvetrain uses hydraulic lash adjusters integrated into
the roller finger followers, providing maintenance-free valve clearance
management.
The fuel system is a high-pressure common rail (HPCR) design operating
at a maximum pressure of 200 MPa (29,000 psi). A gear-type feed pump,
integrated into the high-pressure pump, draws fuel from the tank through
a combined fuel filter and water separator unit. A three-cylinder radial
piston high-pressure pump pressurizes fuel to the common rail reservoir.
The rail distributes fuel to solenoid or piezoelectric injectors for
each cylinder. The injector needles feature a diamond-like carbon (DLC)
coating to reduce friction and improve durability.
The system uses multiple injection events per combustion cycle,
including pilot, main, and post injections. An Engine Control Unit (ECU)
processes inputs from crankshaft position, camshaft position, boost
pressure, intake air temperature, coolant temperature, rail pressure,
and exhaust gas oxygen (NOx) sensors to determine injection timing and
duration. A fuel return line routes excess fuel and injector leakage
back to the tank. Recommended fuel is Diesel #2 with a minimum cetane
rating of 51 for Euro 5 and Euro 6 markets.
The lubrication system is a fully pressurized, wet-sump design with a
high-efficiency gear-type oil pump. The pump is driven from the
crankshaft nose via a chain drive for reduced parasitic loss. An oil
pick-up tube with a screen draws oil from the aluminum structural oil
pan. A spin-on, full-flow oil filter mounts externally on the cylinder
block at the side. The filter incorporates a bypass valve that opens at
1.5 bar (22 psi) differential pressure.
The system includes an integrated oil cooler, a stacked-plate heat
exchanger using engine coolant to regulate oil temperature and mounted
directly to the cylinder block. The main oil gallery runs the full
length of the cylinder block, supplying the five main bearings.
Cross-drilled passages in the crankshaft feed the connecting rod
bearings. A secondary gallery supplies the camshaft bearings, hydraulic
lash adjusters, and the VVT phaser.
The system includes piston cooling oil jets: individual nozzles aimed at
the underside of each piston crown. Total oil system capacity, including
filter and cooler, is 6.2 L (6.6 qt / 1.64 gal). Operating oil pressure
at rated speed is 3.0-4.0 bar (43-58 psi). The oil pressure relief valve
is set at 5.0 bar (72 psi). Graphite-coated piston skirts reduce
internal friction and contribute to improved fuel economy.
The cooling system is a thermostatically controlled, pressurized liquid
cooling system using a belt-driven centrifugal water pump. The pump is
mounted to the front of the cylinder block and driven by the serpentine
accessory belt. Coolant circulates through the block, cylinder head, oil
cooler, EGR cooler, turbocharger bearing housing, and radiator. A
wax-pellet thermostat with a rated opening temperature of 82°C (180°F)
is located in a housing on the water pump inlet. A second thermostat
provides tighter temperature control for high-ambient markets.
The coolant temperature sensor provides input to the ECU and the
instrument panel gauge. The system uses a coolant recovery reservoir
with a pressure cap rated at 1.1 bar (16 psi). Water pump flow capacity
at rated speed is 150 L/min (40 gal/min). Engine jacket water capacity
(engine only) is 8.5 L (9.0 qt / 2.25 gal). Total system coolant
capacity including radiator is 12.0 L (12.7 qt). A single serpentine fan
belt drives all front-end accessories. An automatic tensioner maintains
correct belt tension without manual adjustment.
| Intake and Exhaust Systems |
Air Intake System: A dry-type air cleaner with a replaceable paper
filter element feeds the VGS turbocharger compressor. The variable
geometry system uses movable vanes in the turbine housing to adjust
exhaust flow velocity, providing optimal boost from low engine speeds.
Compressed air passes through an air-to-air intercooler (charge air
cooler) mounted in front of the radiator before entering the intake
manifold. The intake manifold is a plastic composite material with
integrated swirl control valves that generate tumble flow for improved
air-fuel mixing.
Exhaust System: A stainless steel exhaust manifold collects gases from
the four cylinders and directs them to the VGS turbocharger turbine
inlet. A cooled exhaust gas recirculation (EGR) system diverts a portion
of exhaust gas from the exhaust manifold, routes it through a
water-cooled EGR cooler, and reintroduces it to the intake manifold to
reduce combustion temperatures and NOx formation. The EGR valve is
electronically controlled by the ECU. A diesel oxidation catalyst (DOC)
and diesel particulate filter (DPF) are present on Euro 5 and Euro 6
variants. Exhaust gas temperature at rated load is 600-650°C
(1,112-1,202°F) measured before the turbine.
Electrical System: The electrical system operates at 12 volts DC with
negative grounding. The charging system uses a belt-driven alternator
rated at 12V-150A. The starting system includes a reduction-gear starter
motor rated at 12V-2.2 kW. Glow plugs are installed in the cylinder head
for cold start assistance, operating on an ECU-controlled timer relay
that monitors coolant temperature and barometric pressure. Post-heating
continues after engine start to reduce white smoke during warm-up.
Intake Swirl Control: The plastic intake manifold incorporates swirl
control valves that close at low engine speeds to generate high-velocity
tumble within the cylinder, improving fuel atomization and reducing
emissions.
Overall length from the front accessory drive to the flywheel housing
mounting face is 605 mm (23.8 in). Width across the cylinder block,
including the injection pump and turbocharger, is 575 mm (22.6 in).
Height from the oil pan rail to the top of the plastic valve cover is
680 mm (26.8 in).
The dry weight of the fully dressed engine, including flywheel,
alternator, starter, turbocharger, and exhaust manifold but without
fluids, is 190 kg (419 lb). This represents a 60 kg (132 lb) reduction
compared to the 4JK1 engine. The center of gravity is located 350 mm
(13.8 in) from the flywheel housing face and 200 mm (7.9 in) above the
crankshaft centerline.
Engine Oil: The oil and filter change interval is 20,000 km (12,500 mi)
under normal operating conditions or 12 months, whichever occurs first.
For severe service conditions (dusty environments, frequent towing), the
interval reduces to 10,000 km (6,200 mi). Oil specification is API CK-4
or CJ-4, or ACEA C3 for Euro 6 variants. Oil grade is SAE 5W-30 for
general use, or SAE 0W-20 for fuel economy optimization. System volume
is 6.2 L (6.6 qt).
Fuel Filters: The combined fuel filter/water separator element is
replaced every 40,000 km (25,000 mi) or 24 months. The filter
incorporates a water-in-fuel sensor that illuminates a dashboard warning
light. Air Cleaner: The air filter element requires inspection every
20,000 km (12,500 mi) and replacement every 40,000 km (25,000 mi) or
when the restriction indicator shows a vacuum of 6.2 kPa.
Cooling System: Coolant replacement interval is 100,000 km (62,000 mi)
or 48 months. Use a low-silicate, fully formulated ethylene glycol
coolant meeting Isuzu genuine coolant specification. Valve Clearance: No
routine valve lash adjustment is required due to the hydraulic lash
adjuster system. The adjusters are maintenance-free for the engine's
service life. Timing Chain: The timing chain requires no routine
maintenance or replacement under normal operating conditions. Inspection
of chain tensioner extension is recommended at 200,000 km (124,000 mi).
Injector Replacement: Fuel injectors are inspected at 120,000 km (75,000
mi) using ECU diagnostic data. Replacement is required if correction
values exceed specification. Serpentine Belt: The accessory drive belt
is inspected at 40,000 km (25,000 mi) and replaced at 100,000 km (62,000
mi) or earlier if cracking or glazing is observed. The automatic
tensioner is a sealed unit requiring no maintenance.
Cylinder Head Bolts, Stage 1: 30 Nm (22 lb-ft).
Cylinder Head Bolts, Stage 2: 60 Nm (44 lb-ft).
Connecting Rod Bolts: 25 Nm (18 lb-ft).
Main Bearing Cap Bolts (Vertical): 35 Nm (26 lb-ft).
Main Bearing Cross-Bolts (horizontal): 25 Nm (18 lb-ft).
Crankshaft Pulley Bolt: 200 Nm (148 lb-ft).
Flywheel Bolts: 65 Nm (48 lb-ft).
Camshaft Sprocket Bolts: 80 Nm (59 lb-ft).
Intake Manifold Bolts: 22 Nm (16 lb-ft).
Exhaust Manifold Nuts: 28 Nm (21 lb-ft).
Turbocharger Mounting Nuts: 45 Nm (33 lb-ft).
Rocker Shaft (Camshaft Bearing) Bolts: 22 Nm (16 lb-ft).
Valve Cover Bolts: 10 Nm (7 lb-ft).
Oil Pan Bolts (M6): 12 Nm (9 lb-ft).
Oil Pan Bolts (M8): 25 Nm (18 lb-ft).
Glow Plugs: 15 Nm (11 lb-ft).
Injector Clamp Bolts: 25 Nm (18 lb-ft).
EGR Valve Mounting Bolts: 10 Nm (7 lb-ft).
Water Pump Bolts: 12 Nm (9 lb-ft).
Thermostat Housing Bolts: 10 Nm (7 lb-ft).
The Isuzu RZ4E-TC engine is utilized across a range of modern light
commercial vehicles and SUVs from approximately 2016 to the present.
Isuzu D-Max: Second generation (RT85, 2016-2019) and third generation
(RG, 2020-present) across various global markets. Engine codes include
RZ4E-TC for Euro 4 and RZ4E-TC5 for Euro 5 variants.
Isuzu MU-X: First generation (RF, 2013-2020) and second generation (RG,
2020-present). The engine is offered in 4x2 and 4x4 configurations.
Isuzu Taga: Asian market pickup variant based on the D-Max platform.
Holden Colorado: Australian market (2016-2020) using the RZ4E-TC engine
under the 1.9L Duramax branding.
Chevrolet Colorado: Select Asian and Middle Eastern markets
(2016-present) equipped with the RZ4E-TC engine.
Mazda BT-50: Third generation (TF, 2020-present) based on the Isuzu
D-Max platform, sharing the RZ4E-TC powerplant.
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