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Cummins ISM-420 Specifications
| Engine Model: Cummins ISM-420 |
| Engine Type: 4-cycle inline 6-cylinder HPCR or Celect fuel injection liquid-cooled diesel |
| Total Displacement: 661 cu.in (10.8 L) |
| Rated Engine Power: 420 Hp (313 kW) at 2000 rpm |
| Aspiration Type: Turbocharged |
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| General Technical Data |
The Cummins ISM-420 is a high-output, electronically controlled, turbocharged and aftercooled inline six-cylinder diesel engine designed for heavy-duty on-highway trucks, vocational equipment, buses, and industrial machinery. Operating within the ISM/ISM11 engine family, the ISM-420 delivers a rated 420 horsepower and strong mid-range torque, making it well-suited for fleets requiring reliable power, long service life, and reduced operating cost.
he engine combines advanced electronic
management, high-pressure fuel delivery, robust structural components,
and emissions-ready architecture. Its balance of durability,
performance, and serviceability ensures dependable operation in
severe-duty environments.
The ISM-420 is a four-stroke, inline six-cylinder engine with a
displacement of approximately 10.8 liters (659 cubic inches). Bore
measures 125 mm (4.92 in), stroke 147 mm (5.79 in), and compression
ratio typically ranges from 16.5:1 to 17.0:1 depending on emissions
calibration. Rated output: 420 horsepower (313 kW) at 1800–2100 rpm.
Peak torque: 1650–1850 Nm (1217–1365 lb-ft),
typically at 1100–1400 rpm. Idle speed: 650–700 rpm. Firing order:
1–5–3–6–2–4. Turbocharging and charge-air cooling support efficient air
delivery, strong low-speed torque, and improved altitude performance.
Electronic controls manage injection, boost, emissions parameters, and
protection routines.
The block is cast from high-strength iron with reinforcement ribs to
reduce flex under heavy firing pressures. The forged-steel crankshaft is
supported by seven main bearings. Wet or replaceable cylinder liners
simplify overhaul and improve cooling uniformity.
Machined oil galleries supply lubrication to
crankshaft bearings, connecting rods, camshaft bearings, and
piston-cooling jets. Cast-in coolant jackets stabilize thermal load.
Mounting provisions support alternators, PTO drives, hydraulic pumps,
and air compressors common to vocational machinery.
The cast-iron head incorporates optimized combustion chambers. Four
valves per cylinder support airflow and efficient combustion. Valve
actuation uses rocker arms and pushrods driven by a camshaft in the
block. Hardened valve seats and heat-resistant guides tolerate high
exhaust temperatures.
Depending on year, hydraulic lash adjusters may be used. Coolant routing minimizes thermal gradients and prevents gasket failure. A multi-layer steel head gasket provides durable sealing under high peak firing pressures.
| Fuel System |
Depending on production year, the ISM-420 may use Cummins Celect, Celect Plus, or high-pressure common-rail (HPCR) injection. Fuel is drawn through primary and secondary filtration before the high-pressure pump delivers it to electronically actuated injectors. Injection pressure typically exceeds 1400–1600 bar (20,300–23,200 psi).
Multiple injection events–pilot, main, post–enhance efficiency, emissions control, and cold-start behavior. ECM-controlled parameters include crank and cam position, intake temperature, coolant temperature, boost pressure, exhaust temperature, and fuel pressure.
| Lubrication System |
A full-pressure wet-sump system circulates oil using a gear-driven pump. Oil passes through a strainer and full-flow filter to the main gallery, lubricating main bearings, rod bearings, camshaft bearings, rocker assemblies, and turbocharger bearings.
Piston cooling jets lower crown temperature. Normal oil pressure: 300–500 kPa (44–72 psi). Idle pressure: 100–150 kPa (15–22 psi). Oil capacity: 27–33 L (28.5–34.8 qt). Low-ash oil are required for aftertreatment-equipped variants.
| Cooling System |
A liquid-cooled system uses a belt-driven centrifugal water pump. Thermostat begins opening at 82°C (180°F) and fully opens at 95°C (203°F). System pressure: 90–110 kPa (13–16 psi). Coolant capacity: 35–55 L (37–58 qt). Charge-air cooling stabilizes intake temperatures and improves torque and emissions control. Proper coolant chemistry prevents scale, corrosion, and cavitation.
| Other Systems |
Turbocharging: wastegated or variable-geometry turbo depending on calibration. Exhaust systems may include EGR, DOC, DPF, and SCR components depending on tier. Electrical systems operate on 12/24 V with alternators rated 80–150 A. ECM systems monitor sensors, manage derates, and store diagnostic codes. PTO and auxiliary drive options support industrial and vocational configurations.
| Dimensions and Weight |
Length: 1350–1550 mm (53.1–61.0 in)
Width: 800–950 mm (31.5–37.4 in)
Height: 1150–1450 mm (45.3–57.1 in)
Dry weight: 900–1150 kg (1984–2535 lb), depending on configuration.
| Maintenance Data |
Oil and filter: every 500 hours or manufacturer mileage interval.
Fuel filters: 400–500 hours; water separators drained routinely.
Air filter: 200–400 hours depending on dust load.
Coolant: every two years.
Valve lash: inspect on non-hydraulic versions.
Aftertreatment: periodic cleaning or regeneration.
ECM diagnostics support predictive maintenance.
| 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)
Oil drain plug: 40–50 Nm (30–37 lb-ft).
| Vehicle Applications |
The ISM-420 is used in regional-haul tractors, heavy vocational trucks, refuse vehicles, buses, fire engines, concrete mixers, cranes, agricultural machinery, construction equipment, industrial pumps, and generator installations. Its power profile and durability make it suitable for demanding commercial workloads.
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