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Cummins QSF2.8 Specifications
| Engine Model: Cummins QSF2.8 |
| Engine Type: 4-cycle inline 4-cylinder common-rail direct injection liquid-cooled diesel |
| Total Displacement: 171 cu.in (2.8 L) |
| Rated Engine Power: 50-74 Hp (37-55 kW) at 2800 rpm |
| Aspiration Type: Turbocharged |
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| General Technical Data |
The Cummins QSF2.8 is a compact, high-efficiency, electronically controlled, turbocharged and aftercooled four-cylinder diesel engine engineered for modern construction machinery, compact agricultural equipment, mobile industrial platforms, small generator sets, and specialized off-highway applications. As part of the Cummins Quantum System (QS) series, the QSF2.8 combines sophisticated electronic management, high-pressure common-rail fuel injection, enhanced air handling, low emissions, and excellent low-speed torque in a compact, lightweight package.
Designed to meet global emissions regulations
including Tier 4 Final, Stage IIIB, Stage IV, and Stage V (depending on
configuration), the engine provides exceptionally clean combustion and
low noise output while offering strong durability and reduced operating
costs. Because of its small displacement yet strong power-to-weight
ratio, the QSF2.8 is a favored solution for OEMs requiring modern
emissions capability in compact machinery.
The QSF2.8 is a four-stroke, inline four-cylinder diesel engine with a
displacement of approximately 2.8 liters (171 cubic inches). Bore
typically measures 94 mm (3.70 inches), and stroke measures 100 mm (3.94
inches), resulting in an efficient long-stroke design optimized for
torque and fuel efficiency. Compression ratio varies by emissions tier
but commonly falls between 16.0:1 and 17.5:1. Power output generally
ranges from 37 to 55 kW (50–74 horsepower) at approximately 2600–3000
rpm.
Peak torque typically ranges from 200 to 300 Nm
(148–221 lb-ft) at around 1500–1800 rpm. Idle speed is normally set
between 800 and 900 rpm. The firing order is 1–3–4–2. The electronically
controlled turbocharger improves boost response and altitude
compensation, while the high-pressure common-rail system ensures smooth
and efficient combustion over the entire operating range.
The cylinder block is cast from high-strength iron with integrated
reinforcement ribs designed to provide rigidity and suppress vibration
in compact installations. Precisely machined cylinder bores ensure
correct alignment with the forged-steel crankshaft, which is supported
by five main bearings designed for long-term durability.
Coolant jackets cast around each cylinder
stabilize thermal distribution, preventing hotspots. Internally machined
oil galleries supply lubricant to critical components, including main
bearings, connecting rod journals, and piston cooling jets. Threaded
mounts and integrated bosses allow efficient packaging of accessories
such as alternators, air-conditioning compressors, hydraulic pumps, and
generator adaptors.
The cast-iron cylinder head incorporates direct-injection combustion
chambers optimized for modern emissions compliance. Each cylinder uses
four valves–two intake and two exhaust–promoting efficient airflow and
strong mid-range torque. Valves are actuated by rocker arms and pushrods
driven by a camshaft located in the block. Hydraulic lash adjusters may
be installed depending on emissions tier, reducing routine maintenance.
Hardened valve seats and heat-resistant guides withstand severe thermal conditions associated with turbocharged operation. Advanced combustion chamber geometry creates swirl and enhanced mixing, reducing soot formation and improving overall fuel efficiency. Integrated coolant passages help maintain uniform thermal behavior across the head.
| Fuel System |
The QSF2.8 uses a high-pressure common-rail fuel injection system. The low-pressure lift pump supplies fuel to the high-pressure pump, which delivers fuel to the common-rail accumulator at pressures exceeding 1600 bar. Electronically actuated injectors deliver precise fuel quantities with multiple injection events–pilot, main, and post-injection–optimizing combustion, reducing noise, and lowering emissions.
The electronic control module (ECM) continuously monitors engine operating parameters including rail pressure, engine load, crankshaft and camshaft position, boost pressure, coolant temperature, intake temperature, and emissions components. Primary and secondary fuel filters with water separation ensure clean fuel delivery to the high-pressure pump and injectors.
| Lubrication System |
The lubrication system is a full-pressure wet-sump design powered by a gear-driven oil pump. Oil passes through a high-capacity full-flow filter before entering the main oil gallery. Lubrication targets include crankshaft bearings, connecting rod bearings, camshaft journals, rocker arms, and turbocharger bearings.
Piston cooling jets stabilize crown temperature under continuous load. Normal operating oil pressure ranges from 300 to 450 kPa (44–65 psi), while idle pressure is typically 100–150 kPa (15–22 psi). Oil capacity typically ranges from 7 to 9 liters (7.4–9.5 US quarts), depending on sump design. Engines equipped with aftertreatment systems require low-ash lubricants compliant with emissions regulations.
| Cooling System |
A closed-loop liquid cooling system maintains engine temperature across varying duty cycles. A belt-driven centrifugal water pump circulates coolant through block and head passages. A thermostat begins opening at approximately 82°C (180°F) and is fully open by 95°C (203°F). Cooling system pressure is generally 90–110 kPa (13–16 psi).
Coolant capacity typically ranges from 8 to 12 liters (8.5–12.7 US quarts). Charge-air cooling is achieved using either an air-to-air or air-to-water aftercooler depending on installation. Proper coolant mixture prevents corrosion, scale, and cavitation, while the ECM monitors coolant temperature to activate derating strategies if overheating is detected.
| Other Systems |
The turbocharging system may use wastegate or variable-geometry technology depending on version. Charge-air cooling reduces intake temperature, increasing density and improving power and emissions. The intake system incorporates a heavy-duty dry-element air filter with optional dual-stage filtration for dusty environments.
The exhaust system supports modern aftertreatment including DOC (Diesel Oxidation Catalyst), DPF (Diesel Particulate Filter), SCR (Selective Catalytic Reduction), and EGR (Exhaust Gas Recirculation) depending on emissions tier. Electrical configurations include 12-volt or 24-volt systems with alternators ranging from 40 to 100 amperes. The ECM provides continuous diagnostics, limp-mode operation, and service alerts.
| Dimensions and Weight |
Physical dimensions:
Length 700–850 mm (27.6–33.5 inches)
Width 600–750 mm (23.6–29.5 inches)
Height 800–950 mm (31.5–37.4 inches)
Dry weight ranges from 230 to 280 kg (507–617 lbs), depending on
emissions hardware, aftercooler configuration, and accessories. Its
compact footprint supports installation in limited-space machinery
compartments.
| Maintenance Data |
Oil and filter changes are recommended every 500 hours under normal duty, with shorter intervals for severe use. Fuel filters require replacement every 500 hours. Air filter service varies between 250 and 500 hours depending on dust exposure. Coolant should be replaced according to coolant chemistry, generally every two years.
Valve lash inspection may be required on non-hydraulic lifter variants. Aftertreatment components require periodic regeneration or cleaning depending on emissions tier. ECM data logs enable predictive maintenance scheduling.
| Tightening Torques |
Cylinder head bolts: 150–180 Nm (111–133 lb-ft)
Main bearing caps: 120–150 Nm (89–111 lb-ft)
Connecting rod bolts: 60–70 Nm (44–52 lb-ft)
Flywheel bolts: 150–180 Nm (111–133 lb-ft)
Crankshaft pulley bolt: 180–220 Nm (133–162 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 QSF2.8 is widely installed in compact excavators, skid-steer loaders, small wheel loaders, telehandlers, compact tractors, forklifts, forestry attachments, mining support vehicles, industrial pumps, compressors, generator sets, aerial lifts, and machinery requiring high power output in small engine compartments.
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