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Cummins ISX15 Specifications
| Engine Model: Cummins ISX15 |
| Engine Type: 4-cycle inline 6-cylinder Extreme Pressure Injection liquid-cooled diesel |
| Total Displacement: 912 cu.in (15 L) |
| Rated Engine Power: 400-600 Hp (298-447 kW) at 2100 rpm |
| Aspiration Type: Turbocharged and aftercooled |
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| General Technical Data |
The Cummins ISX15 is one of the most widely recognized heavy-duty diesel engines used in long-haul trucks, vocational vehicles, buses, construction equipment, mining machinery, and industrial power units. As a flagship powerplant in the Cummins heavy-duty lineup, the ISX15 delivers a combination of high torque output, excellent fuel efficiency, emissions compliance across multiple global tiers, long service intervals, and strong reliability in severe-duty applications.
Featuring an advanced XPI (Extreme Pressure
Injection) common-rail fuel system, robust electronic engine controls,
cooled EGR (depending on configuration), variable-geometry
turbocharging, and durable cast-iron construction, the ISX15 is
engineered to maintain strong performance over long operating lifespans.
Its refined combustion chamber design, improved airflow characteristics,
and high-pressure injection support quiet operation, low emissions, and
consistent power delivery. The ISX15 has served as a benchmark engine
for Class 8 trucks and heavy industrial platforms for more than a
decade.
The Cummins ISX15 is a four-stroke, inline six-cylinder diesel engine
with a displacement of approximately 15.0 liters (912 cubic inches).
Bore measures about 137 mm (5.39 inches), and stroke measures
approximately 169 mm (6.65 inches), giving the engine a long-stroke
architecture optimized for high torque at low engine speeds. Compression
ratio varies depending on emissions tier–from 16.0:1 in some versions to
approximately 18.0:1 in earlier models. Rated power output typically
ranges from 298 to 447 kW (400–600 horsepower) at approximately
1800–2100 rpm.
Peak torque generally ranges from 2100 to 2500
Nm (1549–1844 lb-ft), commonly delivered around 1000–1400 rpm. Idle
speed is usually set between 600 and 650 rpm. The firing order is
1–5–3–6–2–4. Mechanical enhancements–including friction reduction
measures, optimized piston profiles, and advanced turbocharging–help
maintain strong efficiency, reduce emissions, and support compliance
with global regulations such as EPA10, Euro V, and versions adapted to
meet Euro VI and China VI standards.
The ISX15 cylinder block is cast from heavy-duty compacted graphite iron
or high-strength gray iron depending on the version. Reinforced ribs
reduce block flex and provide greater durability under elevated cylinder
pressures. The forged-steel crankshaft is supported by seven main
bearings designed for long life in continuous heavy-duty cycles. Wet
replaceable cylinder liners offer improved cooling, reduced wear, and
simplified overhaul procedures.
Precision-machined oil galleries distribute
lubrication to critical bearing surfaces. Cast-in coolant jackets
promote even thermal distribution, reducing hotspots and enabling stable
combustion. Piston cooling jets supply pressurized oil to the underside
of each piston to regulate crown temperature in high-power applications.
The block includes mounting pads for PTO units, alternators, A/C
compressors, hydraulic pumps, and additional industrial components.
The cast-iron cylinder head incorporates a modern combustion chamber
optimized for high-pressure injection. Four valves per cylinder–two
intake and two exhaust–improve airflow and enhance combustion stability.
Valve actuation uses rocker arms and pushrods driven by a camshaft
integrated into the block. Exhaust valves are manufactured with
heat-resistant alloys, and hardened valve seats maintain sealing
integrity under heavy thermal cycling.
Integrated coolant passages reduce temperature gradients across the front and rear of the head. A multi-layer steel head gasket is engineered to maintain sealing strength under the high peak firing pressures of the ISX15 platform. Hydraulic lash adjusters may be used in some variants to reduce maintenance requirements.
| Fuel System |
The ISX15 uses the Cummins XPI high-pressure common-rail fuel system. A low-pressure lift pump draws diesel through primary and secondary filtration stages before supplying it to the high-pressure pump. Injection pressures exceed 2000 bar (29,000 psi). Electronically actuated injectors perform multiple injection events during each combustion cycle–including pilot, main, and post injections–to reduce emissions, optimize combustion, minimize noise, and support smooth power delivery.
The ECM monitors dozens of inputs including crankshaft position, camshaft position, exhaust temperature, turbocharger speed, boost pressure, rail pressure, EGR flow (if equipped), intake temperature, coolant temperature, and aftertreatment sensors. Precise control of fuel injection timing and quantity ensures compliance with emissions regulations and maximizes fuel efficiency.
| Lubrication System |
The ISX15 lubrication system is a full-pressure wet-sump design driven by a gear-type oil pump. Oil is drawn through a sump strainer and passed through a high-capacity full-flow oil filter before entering the main gallery. Pressurized oil lubricates crankshaft bearings, connecting rod bearings, camshaft bearings, rocker arms, and turbocharger bearings. Piston cooling jets manage combustion temperature at high loads.
The ISX15 typically operates with oil pressures between 300 and 500 kPa (44–72 psi), while idle pressure generally ranges from 100 to 150 kPa (15–22 psi). Oil capacity ranges from 36 to 44 liters (38.0–46.4 US quarts) depending on sump configuration and emissions equipment. Low-ash oil are required for SCR and DPF-equipped variants to prevent contamination of aftertreatment catalysts.
| Cooling System |
The cooling system consists of a belt-driven centrifugal water pump, radiator, thermostat, hoses, and coolant passages integrated into the block and head. The thermostat begins opening at approximately 82°C (180°F) and fully opens near 95°C (203°F). Cooling system pressure typically ranges between 90 and 110 kPa (13–16 psi). Coolant capacity ranges from 45 to 65 liters (47.5–68.6 US quarts) depending on the installation.
Charge-air cooling reduces intake temperature and supports emissions reduction, torque stability, and efficient combustion. Proper coolant mixture prevents corrosion, cavitation, and scaling. The ECM’s thermal management logic includes temperature monitoring, automatic derate actions, and protective shutdown if coolant temperature exceeds safe limits.
| Other Systems |
Turbocharging is accomplished using a variable-geometry turbocharger (VGT) on most ISX15 variants, providing precise boost control, improved transient response, enhanced braking performance, and optimized EGR flow. Wastegated turbos may be used on specific calibrations. Intake filtration uses heavy-duty dry-element air filters, often with dual-stage filtration.
Exhaust aftertreatment components may include DOC, DPF, SCR, EGR valves, DEF dosers, and ammonia slip catalysts depending on emissions tier. Electrical systems operate on 12- or 24-volt configurations, with alternators rated between 100 and 160 amperes. Sensors throughout the engine provide data to the ECM for diagnostics, derate strategies, power limitation, overspeed protection, and engine braking coordination.
| Dimensions and Weight |
Length: 1400–1600 mm (55.1–63.0 in)
Width: 900–1050 mm (35.4–41.3 in)
Height: 1250–1600 mm (49.2–63.0 in)
Dry weight generally ranges between 1350 and 1500 kg (2976–3307 lbs)
depending on configuration, emissions hardware, and turbocharger type.
| Maintenance Data |
Oil and filter changes typically occur every 500 hours or manufacturer-recommended mileage intervals depending on duty cycle. Fuel filters require replacement every 400–500 hours, and water separators should be drained routinely. Air filter replacement depends on environmental conditions–commonly 200–400 hours. Coolant should be replaced every two years or according to coolant chemistry.
Valve lash inspections may be necessary on engines without hydraulic lash adjusters. DPF and SCR systems require periodic cleaning, forced regeneration, or replacement depending on usage. ECM diagnostic logs assist with predictive maintenance, fault identifi cation, and calibration verification.
| Tightening Torques |
Cylinder head bolts: 220–260 Nm (162–192 lb-ft)
Main bearing caps: 180–220 Nm (133–162 lb-ft)
Connecting rod bolts: 90–120 Nm (66–89 lb-ft)
Flywheel bolts: 300–350 Nm (221–258 lb-ft)
Crankshaft pulley bolt: 280–320 Nm (207–236 lb-ft)
Injector hold-down: 25–30 Nm (18–22 lb-ft)
Intake heater/glow plug (if equipped): 10–15 Nm (7–11 lb-ft)
Oil drain plug: 40–50 Nm (30–37 lb-ft).
| Vehicle Applications |
The ISX15 is widely used in long-haul trucks, heavy vocational trucks, regional-haul tractors, large agricultural equipment, mining support vehicles, cranes, large construction machinery, industrial pumps, compressors, and generator sets. Its high power density, torque capability, emissions features, and strong global support network make it suitable for the most demanding heavy-duty applications.
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