Cat 3508 Specifications
| Engine Model: Caterpillar 3508 |
| Engine Type: 4-stroke 8-cylinder V-block turbocharged liquid-cooled diesel |
| Total Displacement: 2,110 cu.in (34.5 L) |
| Rated Engine Power: 680-1,900 Hp (507-1,417 kW) at 1900 rpm |
| Fuel System Type: Mechanical or Electronic Unit Injector |
____________________________________________________________________________________
The Caterpillar 3508 is a V-8,
four-stroke-cycle diesel engine that forms part of Caterpillar’s
renowned 3500 Series. Designed for durability, high power density, and
long service life, this engine platform serves as the backbone for
demanding applications in industrial, marine, petroleum, and electric
power generation sectors. The 3508 is distinguished by its robust
construction, featuring a deep-skirt cylinder block, individual cylinder
heads, and a modular design that facilitates in-frame overhaul and
maintenance.
Its evolution from mechanical to electronic fuel systems, culminating in
the ACERT technology, allowed it to adapt to tightening emission
regulations while maintaining the reliability for which the series is
known. The engine’s balance of power output, from 680 to 1,900
horsepower, and its high torque rise characteristics make it suitable
for continuous heavy-duty operation in harsh environments.
The Caterpillar 3508 engine family is defined by its foundational
architecture, which remains consistent across industrial, generator set,
marine propulsion, and fire pump variants. The engine configuration is a
60-degree V-8, operating on the four-stroke cycle.
Engine Configuration: V-8, 4-Stroke-Cycle Diesel
Displacement: 34.5 L (2,110 cu.in)
Bore x Stroke: 170 mm x 190 mm (6.7 in x 7.5 in)
Combustion System: Direct Injection.
Horsepower Range: 680 HP to 1,900 HP (507-1,417 kW)
Maximum Torque: 3,144 lb-ft (4,263 Nm) at 1,450 RPM.
Rated Speed: 1,200 to 1,900 RPM.
Generator set models are typically rated at 1,500 RPM or 1,800 RPM.
Aspiration: Turbocharged and Aftercooled (TA). In many configurations,
the aftercooler is a separate circuit (SCAC - Separate Circuit
Aftercooler) using jacket water or a dedicated seawater circuit for
marine applications.
Compression Ratio: Ranges from 13.0:1 to 14.5:1 depending on the
specific model and application. For example, the 3508B high-performance
industrial engine often uses a 14.0:1 ratio, while lower-emission
variants may employ a higher ratio.
The engine’s power ratings are not singular but are defined by the
application and duty cycle. The horsepower and torque figures represent
the broad range available across the 3508, 3508B, 3508C, and 3508E
models.
Emission Standards: The 3508 platform spans several regulatory eras. The
original mechanical unit injection (MUI) versions are non-certified for
unregulated areas. The 3508B model introduced electronic controls to
meet U.S. EPA Tier 1 and IMO I standards. Later 3508C and 3508E models
with ACERT technology are compliant with U.S. EPA Tier 2 and IMO II
emission regulations.
The cylinder block is a high-strength, deep-skirt cast iron design. This
construction provides maximum rigidity to support the crankshaft and
reduce vibration. The deep-skirt design extends the block material below
the crankshaft centerline, providing excellent structural support for
main bearing caps.
The block incorporates replaceable wet cylinder liners, which are
induction-hardened to resist wear and cavitation. The wet liner design
allows coolant to circulate around the liner barrel, promoting uniform
heat dissipation. The use of individual liners and a modular block
architecture enables in-frame engine rebuilds without requiring the
removal of the engine from its installation.
The 3508 engine utilizes individual cylinder heads for each cylinder.
This is a critical design feature that simplifies maintenance and repair
compared to a single cylinder head bank. If a valve train issue or
gasket failure occurs, only the affected cylinder head requires removal,
minimizing downtime and repair complexity.
Each cylinder head is made from cast iron and features a four-valve
cross-flow design - two intake valves and two exhaust valves per
cylinder. This configuration optimizes volumetric efficiency, allowing
for greater air intake and improved exhaust gas scavenging. The valve
train is actuated by a single overhead camshaft per bank, driven by
gears at the front of the engine.
The valve seats and guides are constructed from wear-resistant materials
to withstand the high thermal and mechanical loads associated with high
specific power outputs. Valve lash is adjustable and requires periodic
inspection and setting as part of the maintenance schedule.
The fuel system architecture on the 3508 platform evolved significantly
over its production life to meet increasing performance and emission
demands.
Mechanical Unit Injection (MUI): The original 3508 engines employed a
MUI system. In this design, a mechanical unit injector for each cylinder
is actuated by a camshaft lobe. Fuel injection timing and duration are
controlled by a mechanical governor and a rack linkage system. This
system is robust, fully mechanical, and does not require an external
high-pressure fuel pump.
Electronic Unit Injection (EUI): Beginning with the 3508B model,
Caterpillar introduced EUI. This system replaced the mechanical governor
with an Electronic Control Module (ECM). The ECM controlled the solenoid
on each unit injector, allowing for precise timing and duration control.
This provided improved fuel economy, transient response, and the ability
to monitor engine parameters.
ACERT Technology: Later models (3508C, 3508E) incorporated ACERT
technology. This represents a combination of advanced electronic
control, precision fuel delivery with multiple injection events, and
optimized air management. The system utilizes a high-pressure fuel pump
that supplies fuel to electronically actuated injectors, enabling
injection pressures exceeding 1,800 bar (26,100 psi). ACERT technology
was instrumental in achieving Tier 2 and IMO II emission compliance
without the need for aftertreatment in many applications.
The lubrication system is a high-capacity, gear-driven system designed
to provide continuous oil supply under all operating conditions,
including extreme angles in marine and land drilling applications. A
full-flow oil filter system is standard, often supplemented with a
bypass filter option for enhanced oil cleanliness.
The oil pump is a gear-type pump mounted on the front gear train,
delivering oil to the main oil gallery. From there, oil is distributed
to the crankshaft bearings, camshaft bearings, piston cooling jets, and
valve train. Piston cooling jets are a critical feature, spraying oil to
the underside of the pistons to manage thermal loads.
Oil pan capacity varies significantly by
application:
Standard Industrial Sump: 109 L (28.8 gal)
Deep Sump (Industrial/Generator Set): 174 L (46 gal)
Generator Set (High-Capacity System): The total lubrication system,
including filters and cooler, can hold up to 424 L (112 gal) in large
generator set packages with external systems.
The cooling system is a dual-circuit design on turbocharged and
aftercooled (TA) configurations. The system is engineered to manage the
substantial heat rejection of a high-output V-8 engine.
Jacket Water Circuit: This circuit circulates coolant around the
cylinder liners, cylinder heads, and the turbocharger housing. A
gear-driven centrifugal water pump is standard. The jacket water system
is designed to maintain stable operating temperatures and is integrated
with a radiator for industrial applications or a keel/heat exchanger for
marine use.
Aftercooler Circuit: The separate circuit aftercooler (SCAC) uses a
dedicated pump to circulate coolant through the aftercooler core to
reduce the temperature of the compressed intake air. In marine
applications, this circuit often uses raw seawater. The combination of
jacket water and aftercooler systems results in a large total cooling
capacity.
Engine-Only Jacket Water Capacity: Up to 102.7 L (27.1 gal)
Engine-Only Aftercooler Capacity: 20 L (5.3 gal)
| Intake and Exhaust Systems |
Air Intake System: The system features a heavy-duty turbocharger, either
single or dual depending on the power rating, and an aftercooler. Air
intake filters are heavy-duty cyclonic or radial seal types designed for
extended service intervals in dusty environments.
Exhaust System: A water-cooled turbocharger housing and exhaust manifold
are standard in many marine configurations to reduce surface
temperatures and improve safety. Industrial models utilize dry manifolds
with insulation. Exhaust back pressure is a critical operational
parameter with specified maximum limits.
The engine is equipped with a 24-volt electric starting system with two
or four electric starters, depending on the application. A 24-volt
alternator with integrated regulator provides charging capability. For
generator sets, a separate battery charging alternator is often
included.
Length: 2,136 mm (84.1 in)
Width: 1,703 mm (67 in)
Height: 1,720 mm (68 in)
Dry Weight (Basic Industrial Engine): 4,309 kg (9,500 lbs)
Dry Weight (Fire Pump Engine): Specialized configurations with
heavy-duty flywheel housings and application-specific components can
increase the weight to 5,355 kg (11,805 lbs).
Oil Change Interval: For electronic engines (EUI/ACERT) using
Caterpillar recommended oils and with S·O·S oil analysis, the interval
can be extended to 500 hours. Mechanical engines typically operate on a
250-hour interval under normal duty.
Valve Lash Adjustment: Required at initial 500 hours and every 1,500 to
2,000 hours thereafter. Intake valve lash is set to 0.38 mm (0.015 in),
and exhaust valve lash is set to 0.76 mm (0.030 in) for most models,
with the engine at operating temperature.
Fuel Filter Replacement: Primary and secondary fuel filters are replaced
at 500-hour intervals for electronic engines. Mechanical MUI engines may
have a 250-hour interval.
Overhaul Intervals: With proper maintenance, the engine is capable of a
top-end overhaul (cylinder heads, pistons, rings) at 8,000 to 12,000
hours. A major overhaul, including replacement of bearings and liners,
is typically performed between 16,000 and 24,000 hours, depending on the
application and load factor.
Connecting Rod Cap Nuts: 270 Nm (200 lb-ft).
Main Bearing Cap Bolts: 475 Nm (350 lb-ft).
Cylinder Head Bolts: The final torque for the M30 head bolts is 1,100 Nm
(810 lb-ft).
Cylinder Head Hold-Down Bolts (for individual heads): 470 Nm (350
lb-ft).
Injector Hold-Down Clamp (EUI/ACERT): 55 Nm (41 lb-ft).
Rocker Arm Adjustment Locknut: 55 Nm (41 lb-ft).
Camshaft Drive Gear Bolt: 610 Nm (450 lb-ft).
Flywheel Housing to Block: 100 Nm (74 lb-ft).
Flywheel to Crankshaft: 570 Nm (420 lb-ft).
The Caterpillar 3508 engine is used in a wide array of heavy-duty,
off-highway, and stationary applications where reliability and high
power output are paramount.
Industrial: Power modules for large pumps (dewatering, irrigation),
hydraulic power units, rock crushers, and material handling equipment.
It is also used in land drilling applications to power mud pumps and
drawworks.
Marine: Primary propulsion for commercial vessels such as tugboats,
towboats, fishing vessels, and patrol boats. It also serves as a marine
auxiliary engine for generator sets on larger vessels.
Generator Sets: Stationary and mobile generator sets for prime power in
remote locations, continuous duty for data centers, and standby power
for hospitals and manufacturing facilities. Ratings range from 500 kW to
1,000 kW at 60 Hz.
Fire Pump: A dedicated configuration approved by fire protection
authorities (e.g., FM, UL) for fire pump drivers. These engines feature
specific cooling systems, instrumentation, and enclosures to comply with
stringent safety and reliability standards for fire protection systems.
____________________________________________________________________________________
| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
