Cummins QSB3.3 Specifications
| Engine Model: Cummins QSB3.3 |
| Engine Type: 4-cycle inline 4-cylinder HPCR direct injection liquid-cooled diesel |
| Total Displacement: 201 cu.in (3.3 L) |
| Rated Engine Power: 55-120 Hp (41-90 kW) at 2400 rpm |
| Aspiration Type: Turbocharged |
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The Cummins QSB3.3 is a compact,
high-efficiency, electronically controlled 3.3-liter diesel engine
designed for small to mid-size construction machinery, agricultural
equipment, material-handling machines, generator sets, and specialized
industrial platforms.
The engine is widely used in compact wheel
loaders, skid steers, telehandlers, small excavators, tractors,
forklifts, compressors, pumps, and light industrial power units. Its
combination of mechanical robustness and electronic precision makes it a
reliable and economical power source for modern equipment.
The Cummins QSB3.3 is a four-stroke, water-cooled, turbocharged inline
four-cylinder diesel engine. Displacement is 3.3 liters (201 cubic
inches). Bore is 95 mm (3.74 in) and stroke is 115 mm (4.53 in), giving
the engine a long-stroke design optimized for torque and combustion
efficiency. Compression ratio ranges from 17.2:1 to 18.0:1 depending on
emissions calibration.
Power ratings:
– Construction/machinery: 60–120 hp (45–90 kW) @ 2,200–2,600 rpm
– Agricultural/industrial: 55–110 hp (41–82 kW)
– Generator power (QSB3.3-G): 40–90 kW @ 1,500–1,800 rpm
Peak torque: 240–440 Nm (177–325 lb-ft) @ 1,200–1,600 rpm
Idle speed: 800–900 rpm
Governed speed: 2,500–2,800 rpm
Firing order: 1-3-4-2.
The crankshaft is forged steel with five main bearings. Pistons are cast
aluminum alloy with reinforced combustion bowls and oil-cooling
galleries. Connecting rods are forged steel. The DOHC or SOHC valvetrain
(depending on variant) is gear-driven for lifetime timing stability.
The QSB3.3 block is high-strength cast iron
and includes:
– Parent-bore cylinders
– Deep-skirt construction
– Full-length water jackets
– Thick ribbing for block rigidity
– Oversized main-bearing saddles
The block is designed for high load capability, long service intervals,
and multiple overhauls.
The cast-iron cylinder head includes:
– Two valves per cylinder (mechanical variants)
– Four valves per cylinder (HPCR variants)
– Hardened valve seats and guides
– Central injector placement
– High-efficiency intake and exhaust ports
Cold valve-lash settings (varies by
version):
– Intake: 0.20–0.30 mm (0.008–0.012 in)
– Exhaust: 0.45–0.55 mm (0.018–0.022 in).
The QSB3.3 was produced in several fuel-system configurations:
Mechanical Inline Pump (early versions)
– Simpler mechanical injection
– Lower emissions capability
– Reliable and field-serviceable
High-Pressure Common-Rail (HPCR) Electronic
Injection (later QSB3.3)
– ECM-controlled injectors
– Up to 1,600 bar (23,000 psi) injection pressure
– Multiple injection events for lower noise and emissions
– Improved fuel efficiency
Fuel-system components:
– Electric lift pump
– High-pressure pump (HPCR versions)
– Dual-stage fuel filters
– Water separator
– Rail-pressure sensor
– Timing and metering control (ECM-managed)
Maintenance:
– Fuel filters: 250–500 hr
– Water separator: daily
– Injector testing: 1,200–1,800 hr
– HPCR pump service: major overhaul intervals.
A full-pressure lubrication system is used.
Oil capacity: 7–9 liters (7.4–9.5 qt)
Oil pressure:
– 275–380 kPa (40–55 psi) operating
– 70–100 kPa (10–15 psi) idle
Recommended oil: SAE 10W-30 or 15W-40 (API CI-4, CJ-4, CK-4)
Oil-change interval:
– Industrial: 250–500 hr
– On-road/automotive variants: up to 20,000 km.
The cooling system includes:
– Belt-driven centrifugal water pump
– Thermostat-controlled coolant flow
– Full water-jacketing
– Oil cooler
– Radiator or remote-cooling option
Thermostat:
– Opening: 82°C (180°F)
– Fully open: 95°C (203°F)
Cooling capacity: 10–15 liters (10.6–15.8 qt)
System pressure: 70–100 kPa (10–15 psi).
| Intake and Exhaust Systems |
Intake:
– Dry-type air filter
– Optional dual-stage filtration
– Cyclone pre-cleaner available
Turbocharging:
– Fixed-geometry turbocharger
– Oil-lubricated core
– Optional wastegate control
Aftercooling:
– Air-to-air charge-air cooling (most industrial versions)
Exhaust:
– Cast-iron manifold
– High-temperature turbine housing
– Optional emissions components (EGR, DOC, DPF, SCR depending on
region).
| Electrical and Electronic Systems |
Mechanical versions:
– 12V or 24V starting
– Conventional senders for gauges
Electronic HPCR versions:
– ECM with full electronic fuel management
– Rail-pressure sensor
– Crankshaft and camshaft position sensors
– Oil/coolant temperature sensors
– MAP/boost sensor
– EGR/turbo control (if equipped)
– Diagnostic trouble-code logging
Alternator output: 45–100 amps depending on application.
Optional features:
– PTO drives
– Hydraulic pump mounts
– Air-conditioning compressor mounts
– Remote radiator connections
– Generator housing options
– Belt-drive accessory packages.
Approximate engine dimensions:
– Length: 750–850 mm (29–33 in)
– Width: 600–700 mm (24–28 in)
– Height: 750–900 mm (29–35 in)
Dry weight: 270–340 kg (595–750 lb).
Routine schedules:
– Oil and filter: 250–500 hr
– Fuel filters: 250–500 hr
– Air filter: inspect every 50–100 hr
– Valve adjustment: every 1,000 hr
– Injector service: 1,200–1,800 hr
– Coolant replacement: every 2 years
– Compression test: every 2,000 hr.
– Cylinder-head bolts: 150–170 Nm (111–125 lb-ft) + angle
– Main-bearing caps: 175–200 Nm (129–148 lb-ft)
– Connecting-rod bolts: 65–75 Nm (48–55 lb-ft)
– Flywheel bolts: 100–120 Nm (74–89 lb-ft)
– Crankshaft damper bolt: 200–225 Nm (148–166 lb-ft)
– Oil-drain plug: 40–55 Nm (30–41 lb-ft)
– Injector hold-down: 20–30 Nm (15–22 lb-ft).
The QSB3.3 is used in:
– Compact wheel loaders
– Skid-steer loaders
– Telehandlers
– Mini and mid-size excavators
– Agricultural tractors and sprayers
– Forklifts and material-handling equipment
– Compressors and pumps
– Small generator sets (40–90 kW)
– Municipal utility equipment
– Industrial power units.
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