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Cummins ISX-450ST Specifications
| Engine Model: Cummins ISX-450ST |
| Engine Type: 4-stroke in-line 6-cylinder turbocharged liquid-cooled diesel |
| Total Displacement: 912 cu.in (15 L) |
| Rated Engine Power: 450 Hp (336 kW) at 1800 rpm |
| Fuel System Type: High-Pressure Injection |
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| General Technical Data |
The Cummins ISX-450ST represents a specific
power rating within the renowned Cummins ISX series, a family of
heavy-duty diesel engines that set industry standards for durability,
efficiency, and performance. Built on the robust 15.0L inline-6
platform, this engine was engineered to deliver a compelling balance of
pulling power and fuel economy for on-highway trucking applications.
The “ST” designation typically refers to the “SmartTorque” calibration,
a feature designed to provide a significant torque bulge in the top two
gears, enhancing drivability and reducing shift events under load. This
engine is a cornerstone of modern commercial transportation, known for
its robust construction and sophisticated electronic control systems.
The ISX-450ST is a four-stroke, compression-ignition engine designed for
high-efficiency combustion. Its fundamental architecture is an inline
6-cylinder configuration, which inherently provides excellent primary
and secondary balance, reducing vibration and contributing to engine
longevity.
Engine Configuration: Inline 6-cylinder, 4-stroke diesel
Displacement: 15.0 Liters (912 cubic inches)
Bore x Stroke: 137 mm x 169 mm (5.39 in x 6.65 in)
Aspiration: Turbocharged and Charge Air Cooled
Compression Ratio: 16.5:1
Dry Weight: 3,021 lbs (1,370 kg)
Oil System Capacity: 14 U.S. Gallons (52.9 Liters) including filter
Advertised Horsepower: 450 HP (336 kW) at 1800 RPM
Peak Torque: 1550 lb-ft (2102 Nm) at 1200 RPM
SmartTorque Peak: Up to 1750 lb-ft (2373 Nm) available in the top two
gears
Governed Speed: 2000-2100 RPM
Clutch Engagement Torque: 1000 lb-ft (1356 Nm)
| Cylinder Block |
The foundation of the ISX-450ST is a deep-skirt, cast-iron cylinder
block. This design incorporates a stiff, rigid structure that minimizes
bore distortion and provides exceptional support for the crankshaft and
connecting rods. The deep-skirt construction extends the cylinder block
walls below the crankshaft centerline, enhancing overall rigidity and
reducing noise, vibration, and harshness.
The block features a parent-bore design, meaning the pistons ride
directly on precision-machined surfaces within the block without the use
of separate cylinder liners. This allows for a more rigid block
structure, improved heat transfer, and reduced weight. The block is also
engineered with integrated oil passages that support the high-pressure
fuel system and advanced lubrication requirements.
| Cylinder Head and Valves |
The ISX-450ST utilizes a cross-flow cylinder head design, optimizing
airflow efficiency. In its later evolution, the engine features a single
overhead camshaft (SOHC) arrangement. The cylinder head is a cast-iron
piece, chosen for its thermal stability and strength under the high
cylinder pressures generated by turbocharging and high-injection
pressures.
The valve train consists of four valves per cylinder - two intake and
two exhaust - which improves volumetric efficiency and allows for
central placement of the fuel injector for optimal combustion.
Valve Configuration: 4 valves per cylinder, 24 total
Valve Lash (Intake): 0.013 in (0.33 mm) - cold setting
Valve Lash (Exhaust): 0.025 in (0.64 mm) - cold setting
Valve Adjustment Interval: 500,000 miles (800,000 km)
The overhead cam design reduces the number of moving parts in the valve
train, contributing to more precise valve timing and greater reliability
over extended service intervals.
| Fuel System |
The fuel system on the ISX-450ST varies by production year, representing
a key technological evolution in the ISX platform.
Pre-2010 (HPI System): Older models utilize the HPI (High Pressure
Injection) system. This system employs a dual overhead camshaft
configuration, where one cam operates the valves and the other drives
the unit injectors. The HPI system is capable of generating injection
pressures exceeding 30,000 psi. This system is characterized by its
robust, mechanically-actuated, electronically-controlled unit injectors
that precisely meter and deliver fuel for combustion.
2010 and Later (XPI System): The later ISX15 evolution of this engine
features the XPI (Xtra High Pressure Injection) common rail system. This
system utilizes a single overhead camshaft and a high-pressure fuel pump
that feeds a common rail accumulator. Injectors, controlled by the
engine control module, deliver multiple precise fuel shots per
combustion cycle. The XPI system operates at pressures up to 35,000 psi,
enabling better atomization, reduced combustion noise, and improved
emissions control.
| Lubrication System |
The lubrication system on the ISX-450ST is a high-capacity, full-flow
filtration system designed to support extended maintenance intervals and
severe-duty operation. A high-efficiency, gear-driven oil pump ensures
consistent oil pressure across the entire operating range. The system
includes a spin-on full-flow oil filter and a bypass filter in many
configurations to remove sub-micron contaminants. An integral oil
cooler, utilizing engine coolant, maintains optimal oil temperature.
Oil Pan Capacity: 14 U.S. Gallons (52.9 Liters) - standard
Oil Pressure (Idle, hot): Minimum 10 psi (69 kPa)
Oil Pressure (Rated RPM, hot): 40-70 psi (276-483 kPa)
Oil Change Interval: 15,000 to 35,000 miles (24,000-56,000 km) based on
oil analysis and duty cycle
| Cooling System |
The cooling system is a pressurized, liquid-cooled setup designed to
manage the high thermal loads from the turbocharger, EGR cooler, and the
engine block. The centrifugal water pump is gear-driven for reliability.
The system utilizes a charge air cooler (CAC) to reduce the temperature
of the compressed intake air, increasing its density for improved
combustion efficiency and power output.
Coolant Capacity (Engine Only): 9.5 U.S. Gallons (36 Liters).
Thermostat Opening Temperature: 190°F (88°C).
System Pressure: 15-18 psi (103-124 kPa).
Fan: Belt-driven, variable-speed hydraulic or electronically controlled
viscous fan drive for reduced parasitic losses.
| Air Intake and Turbocharging Systems |
The ISX-450ST is equipped with a Variable Geometry Turbocharger (VGT) from Cummins Turbo Technologies. The VGT uses movable vanes in the turbine housing to optimize airflow across a wide range of engine speeds.
At low RPM, the vanes close to increase exhaust velocity and spool the turbocharger quickly, resulting in minimal lag and high low-end torque. At higher RPM, the vanes open to manage boost pressure and prevent overspeed. This VGT system is also critical for providing the engine braking capability.
| Emissions Systems |
Depending on the production year, the ISX-450ST incorporates a suite of aftertreatment technologies to meet EPA emissions standards.
Cooled Exhaust Gas Recirculation (EGR): Reduces NOx formation by recirculating a portion of cooled exhaust gas back into the intake manifold.
Diesel Particulate Filter (DPF): Traps and oxidizes soot particles from the exhaust stream. The filter passively and actively regenerates to burn off accumulated soot.
Selective Catalytic Reduction (SCR): Reduces NOx levels by injecting Diesel Exhaust Fluid (DEF) into the exhaust stream, which reacts with a catalyst to convert NOx into harmless nitrogen and water.
| Dimensions and Weight |
Dry Weight: 3,021 lbs (1,370 kg)
Length: 55.2 in (1402 mm), from fan to flywheel housing
Width: 35.7 in (907 mm)
Height: 45.3 in (1151 mm)
| Maintenance Data |
Oil and Filter: 15,000 to 35,000 miles (24,000-56,000 km).
Fuel Filter: 25,000 miles (40,000 km).
Coolant Filter: 25,000 miles (40,000 km) or at oil change intervals.
Valve Adjustment: 500,000 miles (800,000 km).
Crankcase Breather: 50,000 miles (80,000 km) - replace filter element.
Air Filter: Inspect at oil change intervals; replace based on
restriction gauge reading.
Drive Belts: Inspect at 100,000 miles (160,000 km); replace as needed.
EGR Valve Cleaning: 150,000 to 200,000 miles (241,000-322,000 km) based
on duty cycle.
| Tightening Torques |
Cylinder Head Bolts (M18 x 2.0): 200 lb-ft (271 Nm)
Connecting Rod Bolts: 75 lb-ft (102 Nm)
Main Bearing Cap Bolts: 175 lb-ft (237 Nm)
Flywheel Bolts: 150 lb-ft (203 Nm)
Injector Clamp Bolts (XPI System): 22 lb-ft (30 Nm)
Valve Rocker Arm Shaft Bolts: 55 lb-ft (75 Nm)
Exhaust Manifold Bolts: 40 lb-ft (54 Nm)
Intake Manifold Bolts: 33 lb-ft (45 Nm)
Oil Pan Bolts: 18 lb-ft (24 Nm)
| Engine Applications |
The Cummins ISX-450ST was specifically calibrated for on-highway,
heavy-duty trucking applications where a balance of high horsepower,
substantial low-end torque, and fuel efficiency are paramount. The
SmartTorque feature made it exceptionally suited for line-haul and
regional haul operations, particularly in applications involving varying
terrain where the extra torque in the top gears reduces shifting
frequency.
Class 8 Line-Haul Trucks: Freightliner Cascadia, Kenworth T680,
Peterbilt 579, Volvo VNL, International ProStar/LoneStar.
Heavy-Duty Vocational Trucks: Dump trucks, cement mixers, and heavy-haul
tractors requiring high low-speed torque.
Refrigerated Vans: Applications where consistent power delivery for
refrigeration units is required.
Tankers and Bulk Haulers: Applications benefiting from the engine’s high
engine braking power for safety and control.
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