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Cummins ISB6.7 Specifications
| Engine Model: Cummins ISB6.7 |
| Engine Type: 4-cycle inline 6-cylinder HPCR direct injection liquid-cooled diesel |
| Total Displacement: 409 cu.in (6.7 L) |
| Rated Engine Power: 197-320 Hp (147-239 kW) at 2300 rpm |
| Aspiration Type: Turbocharged |
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| General Technical Data |
The Cummins ISB6.7 is one of the most widely used medium-duty diesel engines globally, providing a balance of torque, power, reliability, fuel efficiency, and emissions compliance. As a modern continuation of the B-Series platform, the ISB6.7 incorporates advanced electronic control, high-pressure common-rail injection, cooled EGR (depending on version), variable-geometry turbocharging, and sophisticated emissions aftertreatment systems.
It is used extensively in medium-duty trucks,
buses, vocational work vehicles, agricultural machinery, construction
equipment, and industrial power units. Known for its broad torque curve,
excellent low-speed drivability, and long service life, the ISB6.7
remains a preferred engine choice for demanding duty cycles.
The ISB6.7 is a four-stroke, inline six-cylinder diesel engine with a
displacement of approximately 6.7 liters (409 cubic inches). Bore
typically measures 107 mm (4.21 inches), while stroke measures 124 mm
(4.88 inches). Compression ratio varies slightly depending on emissions
tier, commonly between 16.5:1 and 17.3:1. Power output ranges from 147
to 239 kW (197–320 horsepower) at roughly 2300 rpm depending on
calibration.
Peak torque typically falls between 700 and
1100 Nm (516–811 lb-ft), often available at 1300–1600 rpm. Idle speed is
normally set around 750 rpm. The firing order is 1–5–3–6–2–4.
High-pressure common-rail injection, along with precise electronic
control, improves combustion efficiency, reduces noise, and enhances
throttle response.
The cylinder block is constructed from high-strength iron designed to
support high combustion pressures and thermal loads. Reinforcement ribs
add rigidity and reduce vibration. The forged-steel crankshaft rests on
seven main bearings, providing smooth operation and long-term
durability.
Cast-in coolant passages support even thermal
distribution across the cylinders, while machined oil galleries deliver
lubrication to the crankshaft bearings, connecting rods, and upper
engine components. Integrated piston cooling jets help regulate piston
crown temperatures. The block incorporates mounting pads for
alternators, power steering pumps, PTO interfaces, and other accessories
required in medium-duty applications.
The cast-iron cylinder head features an optimized combustion chamber
designed for high-pressure common-rail injection. Four valves per
cylinder–two intake and two exhaust–enhance airflow and combustion
quality. Valve actuation is via rocker arms and pushrods driven by the
camshaft, which is positioned in the block.
Many variants incorporate hydraulic lash adjusters to reduce maintenance requirements. Hardened valve seats and high-temperature-resistant valve guides support durability in turbocharged and EGR-equipped environments. Coolant passages are strategically placed to ensure uniform temperature across the head and reduce thermal stress.
| Fuel System |
The ISB6.7 uses a high-pressure common-rail (HPCR) fuel system. A lift pump draws fuel from the tank through filtration stages before sending it to the high-pressure pump. The high-pressure pump delivers fuel to the common rail with pressures commonly exceeding 1600–1800 bar (23,200–26,000 psi). Electronically actuated injectors deliver fuel in multiple, precisely timed injection events that reduce noise, improve performance, and lower emissions.
The ECM controls injection timing, quantity, and rail pressure based on real-time sensor feedback including crankshaft and camshaft position, boost pressure, intake temperature, coolant temperature, fuel temperature, and emissions sensors. Durable filtration protects sensitive injector components from contamination.
| Lubrication System |
A full-pressure lubrication system is used, with a gear-driven oil pump supplying oil through a metal-mesh pickup and full-flow oil filter. Oil is delivered to main bearings, rod journals, camshaft bearings, rocker arms, and turbo bearings. Piston cooling jets help manage thermal loading during heavy-duty cycles.
Typical operating oil pressure ranges between 300 and 500 kPa (44–72 psi). Idle pressure usually falls between 100 and 150 kPa (15–22 psi). Oil capacity varies depending on sump configuration, generally between 12 and 18 liters (12.7–19 US quarts). Engines equipped with DPF and SCR require low-ash oil for aftertreatment protection.
| Cooling System |
The cooling system includes a belt-driven centrifugal water pump, radiator, thermostat, hoses, and coolant passages. The thermostat begins opening near 82°C (180°F) and becomes fully open around 95°C (203°F). Cooling system pressure typically ranges from 90 to 110 kPa (13–16 psi). Coolant capacity ranges from 15 to 25 liters (15.8–26.4 US quarts).
Charge-air cooling (air-to-air or air-to-water) reduces intake temperatures, supporting strong torque output and efficient combustion. ECM monitoring ensures that derate or shutdown strategies activate under overheating conditions. Maintaining coolant chemistry is essential for preventing corrosion and cavitation.
| Other Systems |
Turbocharging systems vary by emissions tier, ranging from wastegated turbochargers to advanced variable-geometry turbochargers (VGT). VGT provides precise boost control, enhances transient response, and assists with EGR flow regulation. Exhaust systems may incorporate DOC, DPF, SCR, ammonia slip catalysts, and EGR valves depending on emissions tier.
The intake system uses high-capacity dry-element filters, with dual-stage filtration available for dusty applications. Electrical systems operate on 12- or 24-volt configurations, with alternators typically rated between 60 and 120 amperes. The ECM provides a full suite of diagnostics, protection mechanisms, and programmable control strategies.
| Dimensions and Weight |
Physical dimensions:
Length: 1050–1250 mm (41.3–49.2 in)
Width: 700–900 mm (27.6–35.4 in)
Height: 1000–1250 mm (39.4–49.2 in)
Dry weight generally ranges between 480 and 590 kg (1058–1301 lbs)
depending on emissions tier and accessory configuration. Compact,
modular construction allows for flexible installation in a wide range of
chassis and machinery frames.
| Maintenance Data |
Oil and filter changes are recommended every 500 hours or manufacturer-specified mileage depending on duty cycle. Fuel filters require replacement every 500 hours; water separators should be drained regularly. Air filter service intervals vary between 250 and 500 hours depending on dust exposure.
Coolant replacement typically occurs every two years or according to coolant chemistry. Valve lash checks may be required on non-hydraulic versions. Aftertreatment systems require periodic regeneration and cleaning, especially in applications with frequent idling or short duty cycles.
| 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)
Glow plugs/intake heaters: 10–15 Nm (7–11 lb-ft)
Oil drain plug: 30–40 Nm (22–30 lb-ft).
| Vehicle Applications |
The Cummins ISB6.7 is used globally in medium-duty trucks, buses, vocational vehicles, agricultural tractors, wheel loaders, excavators, cranes, industrial pumps, generator sets, and mobile hydraulic equipment. Its combination of torque, efficiency, emissions capability, and reliability makes it one of the most adaptable engines in the medium-duty sector.
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