Cat C4.4 ACERT Specifications
| Engine Model: Caterpillar C4.4 ACERT |
| Engine Type: 4-cycle inline 4-cylinder common-rail direct injection liquid-cooled diesel |
| Total Displacement: 268 cu.in (4.4 L) |
| Rated Engine Power: 70-140 Hp (52-104 kW) at 2200 rpm |
| Aspiration Type: Turbocharged |
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The Caterpillar C4.4 ACERT engine is a modern,
highly efficient, mid-displacement diesel engine engineered for
construction, agricultural, industrial, and generator-set applications.
As part of Caterpillar’s ACERT (Advanced Combustion Emissions Reduction
Technology) lineup, the C4.4 ACERT uses electronically controlled
high-pressure fuel injection, optimized combustion sequencing,
turbocharging, and multiple emissions-control strategies to meet
stringent Tier 3, Tier 4 Interim, Tier 4 Final, and Stage V regulations.
The engine delivers excellent fuel efficiency, high torque at low-to-mid
RPM, superior cold-start performance, and long-term durability under
continuous-duty operation.
Designed around a robust cast-iron structure with a parent-bore block,
high-strength rotating assembly, and advanced electronic control, the
C4.4 ACERT is a versatile powerplant known for its reliability,
smoothness, and ease of service. Its modular design allows easy
installation in compact wheel loaders, telehandlers, mini excavators,
agricultural equipment, compressors, generators, and other demanding
industrial platforms.
The Caterpillar C4.4 ACERT is a four-stroke, water-cooled, inline
four-cylinder diesel engine with high-pressure common-rail injection and
turbocharging. Displacement is 4.4 liters (268 cubic inches). Bore is
105 mm (4.13 in), and stroke is 127 mm (5.00 in), resulting in a
long-stroke configuration that supports torque-heavy applications.
Compression ratio varies by emissions configuration and typically ranges
from 16.5:1 to 18.2:1.
Power ratings vary significantly:
— Industrial and construction: 75–140 hp (56–104 kW) at 2,200–2,400 rpm
— Agricultural: 70–130 hp (52–97 kW)
— Generator-drive: 55–125 kW standby at 1,500–1,800 rpm
Peak torque typically ranges: 350–550 Nm (258–406 lb-ft) at 1,400–1,800
rpm. Idle speed is commonly 750–850 rpm, and maximum governed speed
typically ranges from 2,200 to 2,400 rpm. Firing order is 1-3-4-2.
The crankshaft is forged steel, fully counterweighted, and supported by
five large main bearings. Pistons are cast-aluminum alloy with
reinforced crowns and optimized combustion bowls for multi-event fuel
injection. Connecting rods are forged steel with replaceable inserts.
The camshaft is mounted in the block and gear-driven for long-term
timing accuracy.
The cylinder block is cast iron with parent-bore cylinders and deep
reinforcement ribs that reduce distortion and provide maximum stiffness.
Coolant passages fully surround the cylinders for stable thermal
characteristics. A large-capacity oil gallery is integrated into the
block to ensure consistent lubrication.
The block includes mounting bosses for hydraulic pumps, auxiliary
drives, alternators, air compressors, and emissions-control devices.
The cylinder head is cast iron and incorporates four valves per
cylinder—two intake and two exhaust—to optimize breathing efficiency and
combustion performance. The valvetrain consists of pushrods and rocker
arms actuated by the gear-driven camshaft. Hardened valve seats ensure
long service life under high thermal loads.
Typical valve-lash (cold):
— Intake: 0.25–0.30 mm (0.010–0.012 in)
— Exhaust: 0.30–0.35 mm (0.012–0.014 in).
The C4.4 ACERT uses an electronically controlled high-pressure
common-rail fuel system. Injection pressures range from 1,200 to 1,800
bar depending on load and emissions tier. The ECM controls injection
timing, duration, and multiple fuel events for optimal combustion.
Fuel system components include:
— Electric or mechanical lift pump
— Water separator
— Primary and secondary fuel filters
— High-pressure common-rail pump
— Electronically actuated injectors
Fuel-system maintenance:
— Replace filters every 250–300 hours
— Drain water separator as needed
— Inspect injectors every 1,000–1,500 hours
— Maintain ultra-clean fuel to protect rail components.
The engine uses a full-pressure wet-sump lubrication system with a
gear-driven oil pump. Oil is filtered through a full-flow cartridge
filter.
Oil capacity: 8–10 L (8.5–10.6 qt)
Operating oil pressure: 300–450 kPa (44–65 psi)
Idle pressure: 100–150 kPa (15–22 psi)
Recommended oils include SAE 10W-30 or 15W-40 (API CI-4 or higher). Oil
changes typically occur every 250 hours in industrial duty cycles.
Cooling is provided by a belt-driven centrifugal water pump. Coolant
flows through the block, head, turbocharger (where applicable),
aftercooler, radiator, and optional oil cooler.
Thermostat:
— Opening temperature: 82°C (180°F)
— Fully open: 95°C (203°F)
Cooling-system capacity typically ranges from 12 to 16 L (12.7–17 qt).
System pressure: 70–100 kPa (10–15 psi).
| Intake and Exhaust Systems |
The C4.4 ACERT uses turbocharging, and many models include air-to-air
aftercooling. Emissions-certified versions integrate DOC, DPF, and/or
SCR aftertreatment.
Air filtration options:
— Dual-stage dry filters (construction)
— Cyclone pre-cleaners (agriculture)
— Large industrial canister filters (stationary)
The exhaust manifold is high-temperature cast iron, designed for
durability under constant thermal cycling.
| Electrical and Starting Systems |
Electrical systems include both 12-volt and 24-volt configurations. The
ECM manages fuel injection, cold-start strategy, turbocharger response,
aftertreatment, and engine-protection logic.
Electrical components:
— Alternator: 45–100 amps
— Starter motor: 3–4 kW
— Sensors: coolant temperature, oil pressure, crankshaft position,
intake-air temperature, boost pressure, fuel temperature, aftertreatment
temperature and pressure.
Depending on installation, the C4.4 ACERT
may support:
— PTO and auxiliary pump drives
— Hydraulic power units
— Generator heads
— Remote cooling systems
— Belt-driven accessories
— Air compressors.
Approximate physical dimensions:
— Length: 820–960 mm (32–38 in)
— Width: 600–700 mm (24–28 in)
— Height: 830–950 mm (33–37 in)
Dry weight: 350–450 kg (772–992 lb).
— Oil and filter: 250 hr
— Fuel filters: 250–300 hr
— Air filters: inspect every 50 hr
— Coolant: replace every 2 years
— Valve adjustment: every 1,000 hr
— Injector inspection: 1,000–1,500 hr
— Compression test: every 2,000 hr
— Belt inspection: every service cycle.
— Cylinder head bolts: 140–160 Nm (103–118 lb-ft)
— Main bearing caps: 180–210 Nm (133–155 lb-ft)
— Connecting rods: 70–85 Nm (52–63 lb-ft)
— Flywheel bolts: 160–190 Nm (118–140 lb-ft)
— Crankshaft pulley bolt: 220–260 Nm (162–192 lb-ft)
— Oil drain plug: 35–45 Nm (26–33 lb-ft)
— Injector hold-downs: 25–30 Nm (18–22 lb-ft).
The Caterpillar C4.4 ACERT engine is used
in:
— Compact wheel loaders
— Backhoe loaders
— Telehandlers
— Mini excavators
— Agricultural sprayers
— Compact tractors
— Forklifts
— Skid-steer loaders
— Generator sets (50–125 kW range)
— Hydraulic power units
— Industrial compressors.
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