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Cummins ISC-300 Specifications
| Engine Model: Cummins ISC-300 |
| Engine Type: 4-cycle 6-cylinder CAPS or common-rail fuel injection liquid-cooled diesel |
| Total Displacement: 505 cu.in (8.3 L) |
| Rated Engine Power: 300 Hp (224 kW) at 2200 rpm |
| Aspiration Type: Turbocharged and aftercooled |
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| General Technical Data |
The Cummins ISC-300 is a high-performance, electronically controlled, turbocharged and aftercooled inline six-cylinder diesel engine designed for medium-duty trucks, buses, vocational equipment, agricultural machinery, construction equipment, industrial pumps, and stationary power units. As part of the ISC/ISL engine family, the ISC-300 emphasizes fuel efficiency, high torque density, serviceability, and long overhaul life.
With a 300-horsepower rating, the ISC-300 is
engineered for demanding duty cycles including regional haul, urban
transit, vocational work, and off-highway operations. The engine
integrates an advanced electronic control module, high-pressure fuel
delivery, refined combustion design, and robust mechanical architecture.
These features provide smooth power delivery, strong low-end response,
efficient fuel consumption, and reliable operation in severe
environments.
The Cummins ISC-300 is a four-stroke, inline six-cylinder diesel engine
with a displacement of approximately 8.3 liters (505 cubic inches). Bore
typically measures 114 mm (4.49 inches), while stroke measures 135 mm
(5.31 inches), supporting a torque-rich long-stroke configuration.
Compression ratio commonly falls between 16.5:1 and 17.5:1 depending on
calibration. Rated power output is approximately 224 kW (300 horsepower)
at around 2200 rpm.
Peak torque normally ranges from 950 to 1150 Nm
(701–848 lb-ft), generally achieved at 1300–1500 rpm. Idle speed
typically ranges from 750 ± 50 rpm. Firing order is 1–5–3–6–2–4.
Turbocharging and air-to-air charge-air cooling increase air density,
improving combustion efficiency, response, and thermal stability.
Electronic engine management synchronizes injection, boost, timing, and
protective derates.
The cylinder block is cast from high-strength iron designed to withstand
elevated cylinder pressures. Reinforcement ribs minimize deflection and
vibration under high load. The forged-steel crankshaft is supported by
seven large main bearings engineered for durability under continuous
heavy-duty operation. Wet or replaceable cylinder liners (depending on
version) provide consistent cooling and ease of overhaul.
Internal oil galleries distribute pressurized
oil to bearings, piston jets, and camshaft journals. Cast-in coolant
jackets regulate temperature around all cylinders. Threaded mounting
bosses support PTO drives, alternators, air-conditioning compressors,
and hydraulic pump adaptors, enabling integration into various vehicle
and industrial platforms.
The cast-iron cylinder head uses direct-injection combustion chambers
optimized for high-pressure fuel systems. Each cylinder incorporates
four valves–two intake and two exhaust–supporting efficient airflow and
reduced emissions. Valves are actuated by rocker arms and pushrods
driven by a camshaft mounted in the block. Hardened valve seats and
high-temperature-resistant guides tolerate thermal stress typical of
turbocharged operation.
Hydraulic lash adjusters may be included depending on model version. The combustion chamber design promotes swirl and rapid air–fuel mixing, improving torque output and fuel efficiency. Integrated coolant passages reduce hotspots and prevent thermal deformation. A reinforced head gasket design ensures sealing under high peak cylinder pressures.
| Fuel System |
The ISC-300 employs an electronically controlled high-pressure injection system, such as the Cummins CAPS (Accumulator Pump System) or high-pressure common-rail depending on model year. Fuel is drawn by a lift pump through primary and secondary filtration into the high-pressure pump. Injection pressures typically exceed 1400–1600 bar (20,300–23,200 psi). Electronically actuated injectors deliver fuel with precise timing and quantity to optimize combustion and emissions.
Multiple injection events–pilot, main, and post injection–improve noise control and reduce particulate formation. The electronic control module (ECM) monitors rail pressure, crankshaft and camshaft position, boost pressure, intake temperature, coolant temperature, and exhaust temperature to optimize injection. Excess fuel returns to the tank to maintain injector cooling and pressure balance.
| Lubrication System |
A full-pressure lubrication system supports long service life. A gear-driven oil pump draws oil from the sump through a mesh pickup, delivering it through a replaceable full-flow oil filter into the main gallery. Pressurized oil reaches crankshaft bearings, connecting rod journals, camshaft bearings, rocker arms, and turbocharger bearings.
Piston cooling jets reduce crown temperature under heavy load. Normal operating oil pressure ranges from 300 to 500 kPa (44–72 psi). Idle pressure typically ranges between 100 and 150 kPa (15–22 psi). Oil capacity typically falls between 20 and 25 liters (21.1–26.4 US quarts). Low-ash oil are required on aftertreatment-equipped engines.
| Cooling System |
The ISC-300 uses a liquid cooling system consisting of a belt-driven centrifugal water pump, thermostat, radiator, hoses, and coolant passages. The thermostat begins to open at approximately 82°C (180°F) and is fully open near 95°C (203°F). Cooling system pressure typically ranges between 90 and 110 kPa (13–16 psi).
Coolant capacity ranges between 25 and 35 liters (26.4–37.0 US quarts) depending on installation. Air-to-air charge-air cooling stabilizes intake temperature, enhancing performance and reducing emissions. Proper coolant mixture prevents corrosion, scale, cavitation, and liner pitting. The ECM monitors coolant temperature for derate and shutdown protection.
| Other Systems |
Turbocharging increases intake air density and torque output. Depending on configuration, the ISC-300 may use wastegated or VGT (variable-geometry turbocharging). The intake system uses a heavy-duty dry-element filter, with optional dual-stage filtration. The exhaust system may include DOC, DPF, SCR, and EGR depending on the emissions tier.
Electrical systems operate at 12- or 24-volt configurations, with alternators typically rated between 60 and 120 amperes. ECM-controlled systems provide diagnostics, protection strategies, and advanced calibration options. Accessory interfaces include PTO drives, hydraulic pump mounts, and additional bracketry.
| Dimensions and Weight |
Length: 1150–1350 mm (45.3–53.1 in)
Width: 750–900 mm (29.5–35.4 in)
Height: 1050–1350 mm (41.3–53.1 in)
Dry weight normally ranges from 650 to 800 kg (1433–1764 lbs), depending
on cooling system, turbocharger, and accessories. The compact, modular
layout supports installation in medium-duty vehicles and industrial
frames.
| Maintenance Data |
Oil and filter changes are recommended every 500 hours or at manufacturer-specified mileage depending on duty cycle. Fuel filters should be replaced every 500 hours, with routine draining of water separators. Air filter service ranges from 250 to 500 hours depending on environmental dust exposure. Cooling system service intervals generally require replacement every two years.
Valve lash inspection may be necessary on engines without hydraulic adjusters. Aftertreatment systems require periodic inspection, regeneration, or servicing. ECM diagnostics support predictive maintenance and troubleshooting.
| Tightening Torques |
Cylinder head bolts: 180–210 Nm (133–155 lb-ft)
Main bearing caps: 150–180 Nm (111–133 lb-ft)
Connecting rod bolts: 70–90 Nm (52–66 lb-ft)
Flywheel bolts: 220–260 Nm (162–192 lb-ft)
Crankshaft pulley bolt: 240–280 Nm (177–207 lb-ft)
Injector hold-down: 20–25 Nm (15–18 lb-ft)
Intake heaters/glow plugs (if equipped): 10–15 Nm (7–11 lb-ft)
Oil drain plug: 30–40 Nm (22–30 lb-ft).
| Vehicle Applications |
The Cummins ISC-300 powers regional haul trucks, vocational dump trucks, fire trucks, concrete mixers, school buses, transit coaches, agricultural tractors, construction machinery, industrial compressors, and generator systems. Its balance of power, torque, emissions capability, and durability makes it suitable for demanding environments.
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