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Cummins 6BT5.9-G2 Specifications
| Engine Model: Cummins 6BT5.9-G2 |
| Engine Type: 4-cycle inline 6-cylinder direct-injection liquid-cooled diesel |
| Total Displacement: 359 cu.in (5.9 L) |
| Rated Engine Power: 114-201 Hp (85-150 kW) at 2300 rpm |
| Aspiration Type: Turbocharged |
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| General Technical Data |
The Cummins 6BT5.9-G2 is a mechanically governed, turbocharged diesel engine recognized globally for its rugged durability, fuel efficiency, and reliability in continuous-duty generator applications. As a part of the respected Cummins B Series lineup, the engine is engineered to provide high torque at low-to-mid engine speeds, excellent load acceptance, and simplified maintenance.
The 6BT5.9-G2’s cast-iron construction,
mechanical fuel system, and strong rotating assembly make it highly
suitable for harsh environments, remote installations, and industrial
settings requiring long operating hours and minimal downtime. The engine
is widely deployed in generator sets, construction equipment,
agricultural machinery, industrial pumps, mining support machines, and
off-road platforms.
The Cummins 6BT5.9-G2 is an inline, six-cylinder, four-stroke diesel
engine with a displacement of approximately 5.9 liters (359 cubic
inches). Bore is 102 mm (4.02 inches), while stroke measures 120 mm
(4.72 inches), forming a long-stroke configuration optimized for torque
production. Compression ratio generally ranges from 16.5:1 to 17.5:1
depending on calibration.
Power output varies across generator
configurations but typically falls between 85 and 150 kW (114–201
horsepower) at 1500–2500 rpm. Peak torque generally ranges from 420 to
650 Nm (310–479 lb-ft) at approximately 1300–1600 rpm. Idle speed is
commonly around 750 ± 50 rpm. The firing order is 1–5–3–6–2–4.
Turbocharging improves air density and torque, ensuring stable operation
even under heavy continuous load or high ambient temperatures.
The engine block is cast from high-strength iron and includes deep
reinforcement ribs to reduce vibration and structural flex. The inline
six-cylinder layout provides balanced firing intervals and smooth
operation. The forged-steel crankshaft is supported by seven
precision-machined main bearings, providing long-term reliability under
continuous-duty conditions.
The block contains cast-in coolant jackets
surrounding each cylinder to ensure even temperature control, while
machined oil galleries distribute lubrication to critical bearing
surfaces, piston-cooling jets, and camshaft bearings. Accessory mounting
bosses and threaded ports allow flexible installation of alternators,
generator adaptors, hydraulic pumps, and equipment-specific accessories.
The cast-iron cylinder head incorporates direct-injection combustion
chambers designed for turbocharged operation. Each cylinder is equipped
with two intake and two exhaust valves actuated by pushrods and rocker
arms driven by a camshaft located in the block. Valve lash is manually
adjustable and requires periodic inspection to maintain proper breathing
efficiency, combustion stability, and valve seat integrity.
Hardened valve seats and heat-resistant guides support high-temperature operation. The combustion chamber design enhances swirl and fuel-air mixing for efficient combustion and strong torque characteristics. Integrated coolant passages maintain stable thermal behavior and minimize the risk of overheating.
| Fuel System |
The Cummins 6BT5.9-G2 uses a mechanical direct-injection fuel system consisting of a lift pump, water separator, primary and secondary filters, and a high-pressure injection pump. The mechanical injection pump meters fuel and maintains injection timing. Injection pressures typically range between 250 and 320 bar, enabling fine fuel atomization through multi-hole injector nozzles.
Excess fuel is routed back to the tank to help cool the injectors and stabilize fuel temperature. Some variants include an aneroid boost compensator to adjust fueling according to turbocharger boost pressure, improving performance and reducing smoke. Mechanical governors regulate engine speed and ensure stable generator output frequency.
| Lubrication System |
The full-pressure lubrication system includes a gear-driven oil pump that draws oil from the sump through a mesh strainer and forces it through a full-flow spin-on filter. Pressurized oil is directed to the crankshaft main bearings, connecting rod journals, camshaft bearings, rocker arms, and turbocharger bearings. Piston-cooling oil jets reduce thermal loading during sustained high-output operation.
Operating oil pressure is typically 300–450 kPa (44–65 psi), while idle pressure ranges from 100 to 150 kPa (15–22 psi). Oil capacity is generally between 13 and 16 liters (13.7–16.9 US quarts). High-quality diesel engine oil meeting API CF or higher specifications is recommended.
| Cooling System |
The cooling system is liquid-based and includes a belt-driven centrifugal water pump, radiator, thermostat, coolant passages, and hoses. Coolant circulates through the block and head, absorbing heat and maintaining stable temperatures. The thermostat begins opening at approximately 82°C (180°F) and is fully open at about 95°C (203°F).
Cooling system pressure typically ranges from 90 to 110 kPa (13–16 psi). Coolant capacity usually ranges from 15 to 20 liters (15.8–21.1 US quarts). Proper coolant mix protects against corrosion, scaling, and cavitation. Some industrial configurations include remote radiators or heavy-duty cooling packs.
| Other Systems |
Turbocharging increases intake air density, enhancing torque output and fuel efficiency. Aftercooling may be included depending on configuration; aftercoolers lower intake charge temperature and improve combustion. The intake air system includes a dry-element air filter with optional dual-stage filtration for dusty work environments.
The cast-iron exhaust manifold is engineered to withstand high thermal cycling. Electrical systems are available in 12- or 24-volt configurations, with alternators rated between 35 and 90 amperes. The reduction-gear starter ensures reliable cold cranking. Optional PTO drives, hydraulic pump adapters, air compressors, and additional accessories expand versatility.
| Dimensions and Weight |
Physical dimensions include:
Length 1050–1200 mm (41.3–47.2 inches)
Width 700–800 mm (27.6–31.5 inches)
Height 950–1150 mm (37.4–45.3 inches)
Dry weight ranges from 430 to 500 kg (948–1102 lbs), depending on turbo configuration and accessory package. Its compact but sturdy construction supports installation in generator housings, agricultural machines, and industrial frames.
| Maintenance Data |
Oil and filter replacement is recommended every 250 hours under generator or industrial duty cycles. Fuel filters should be serviced every 250–400 hours. Air filter maintenance varies depending on environmental conditions and typically ranges from 100 to 300 hours. Valve lash inspection should occur every 500–600 hours.
Coolant replacement is generally recommended every two years or 2000 hours. Injector servicing, including spray testing and cleaning, is typically performed every 1500–2000 hours. Pump timing checks are recommended at major service intervals. Compression testing around 3000 hours provides insight into internal wear.
| Tightening Torques |
Cylinder head bolts: 160–180 Nm (118–133 lb-ft)
Main bearing cap bolts: 150–170 Nm (111–125 lb-ft)
Connecting rod bolts: 70–85 Nm (52–63 lb-ft)
Flywheel bolts: 180–220 Nm (133–162 lb-ft)
Crankshaft pulley bolt: 200–240 Nm (148–177 lb-ft)
Injector hold-down bolts: 20–25 Nm (15–18 lb-ft)
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 6BT5.9-G2 powers agricultural tractors, excavators, wheel loaders, backhoe loaders, mining support equipment, forklifts, compressors, pumps, generator sets, and industrial machines. Its combination of mechanical simplicity, fuel efficiency, high torque, and long service life makes it suitable for continuous-duty service in diverse global markets.
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