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Cummins 6LTAA8.9-G2 Engine

The Cummins 6LTAA8.9-G2 is a heavy-duty, 8.9-liter, 4-stroke, inline 6-cylinder diesel engine engineered primarily for stationary and industrial power generation (G-drive) applications. The engine utilizes an advanced long-stroke design combined with a 4-valve-per-cylinder layout to achieve complete gas expansion and high thermal efficiency. Structurally, it features an enhanced, low-vibration cast-iron cylinder block and forced-cooling hinged pistons to withstand intensive mechanical and thermal stresses during continuous operation.

The alphanumeric designation breaks down as: 6 cylinders, L series engine platform, Turbocharged, AA Air-to-Air charge cooling, 8.9 liters displacement, Generator drive application, and 2 power rating index with electronic speed regulation. The combustion chamber geometry relies on an under-square, long-stroke configuration to maximize torque delivery at low operational speeds. The nominal cylinder bore is 114 mm. The piston stroke length is 145 mm. The total engine displacement measures 8.9 liters.

Fuel delivery relies on a mechanical high-pressure fuel injection system paired with an electronic governor for precise frequency control. High-pressure fuel delivery is generated via an inline BYC P7100 type injection pump. Engine speed governance and droop control are managed by a GAC electronic governor system, providing tight transient response and a speed-droop specification within 5%. Fuel injectors are arranged in a center-symmetrical layout directly above the combustion bowl, creating a highly uniform fuel-air mixture for efficient, low-emission combustion.

The engine uses a full-pressure, forced lubrication system driven by a gear-type oil pump integrated directly into the cylinder block. Total lubrication system oil capacity is 27.6 liters, encompassing the oil pan and oil filters. Standard oil pressure under rated speed conditions ranges between 300 kPa and 450 kPa. The system requires high-grade diesel engine oil meeting or exceeding API CF-4 specifications. It includes an integrated oil cooler assembly to regulate oil temperature under maximum load conditions.

Cooling System: Thermal regulation is managed by a closed-loop liquid-cooling architecture with a pressurized system configuration. Component layout includes a heavy-duty water pump, a thermostat to regulate engine operating temperatures, and an air-to-air charge air cooler (intercooler) to reduce intake air temperatures before it enters the cylinders.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6LTAA8.9-G2
Engine Type ............... 4-cycle inline 6-cylinder direct injection turbocharged liquid-cooled diesel
Number of Cylinders ............... 6
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.49 (114.0)
Engine Stroke, in (mm) ............... 5.71 (145.0)
Displacement, cu.in (L) ............... 543 (8.9)
Rated Engine Power, hp (kW) ............... 241-402 (180-300)
Rated Engine Speed, rpm ............... 1500-2200
Peak Torque ............... 1100-1500 Nm (811-1106 lb-ft) at 1300-1500 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged and aftercooled
Compression Ratio ............... 16.5:1-17.5:1
Firing Order ............... 1-5-3-6-2-4
Cylinder Block Type ............... Cast iron
Cylinder Head Type ............... Cast iron
Lubrication System ............... Full-pressure
Oil Pump Type ............... Gear-driven
Oil Filter Type ............... Full-flow, spin-on
Cooling System ............... Liquid-cooled
Water Pump Type ............... Belt-driven, centrifugal
Air Cleaner Type ............... Dry dual-stage
Starting System ............... Electric Starter
Electrical System ............... 12V or 24V
Alternator Rating, Amps ............... 50-120

Fuel System

Fuel System ............... Direct injection
Injection Pump Type ............... Rotary or inline
Fuel System Control ............... Mechanical
Governor Type ............... Mechanical
Fuel Injector Type ............... Multi-hole
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 53.1-65.0 (1350-1650)
Overall Width, in (mm) ............... 31.5-37.4 (800-900)
Overall Height, in (mm) ............... 47.2-59.1 (1200-1500)
Dry Weight, lbs (kg) ............... 1650-1980 (750-900)

Maintenance Data

Service Information

Thermostat begins opening ............... 82C (180F)
Thermostat fully open ............... 95C (203F)
Cooling system pressure ............... 70-100 kPa (10-15 psi)
Operating oil pressure ............... 300-450 kPa (44-65 psi)
Idle oil pressure ............... 100-150 kPa (15-22 psi)
Intake Valve Clearance, in (mm) ............... 0.012 (0.30)
Exhaust Valve Clearance, in (mm) ............... 0.024 (0.61)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CF or higher
Engine Oil Capacity, qts (L) .................. 23.1-29.4 (22.0-28.0)
Coolant Capacity, qts (L) ............... 31.5-42.0 (30.0-40.0)

Service Intervals

Change oil and filter ............... Every 250 hours
Replace fuel filters ............... Every 300 hours
Inspect air filter ............... Every 100 hours
Replace air filter ............... Every 300 hours
Change coolant ............... Every 2000 hours
Valve-lash adjustment ............... Every 1000 hours
Injector inspection ............... Every 1500-2000 hours
Compression test ............... Every 2500 hours
Drain water separator ............... As required
Belt inspection ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 114.00-114.04 (4.488-4.490)
Crankshaft Journal Outside Diameter, in (mm) ............... 97.96-98.00 (3.857-3.858)
Crank Pin Outside Diameter, in (mm) ............... 75.96-76.00 (2.991-2.992)
Crankshaft End Play, in (mm) ............... 0.13-0.38 (0.005-0.015)
Intake Valve Stem Outside Diameter, in (mm) ............... 8.95-8.97 (0.352-0.353)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 8.93-8.95 (0.351-0.352)
Intake Valve Guide Inside Diameter, in (mm) ............... 9.02-9.07 (0.355-0.357)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 9.02-9.07 (0.355-0.357)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.05-0.12 (0.002-0.005)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.07-0.14 (0.003-0.006)
Intake Valve Spring Free Length, in (mm) ............... 62.50 (2.461)
Exhaust Valve Spring Free Length, in (mm) ............... 62.50 (2.461)
Intake Cam Height, in (mm) ............... 51.80-52.40 (2.039-2.063)
Exhaust Cam Height, in (mm) ............... 51.40-52.00 (2.024-2.047)
Piston Pin Outside Diameter, in (mm) ............... 44.99-45.01 (1.771-1.772)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.01-0.03 (0.0004-0.0012)
Second Ring Side Clearance, in (mm) ............... 0.07-0.12 (0.0028-0.0047)
Oil Ring Side Clearance, in (mm) ............... 0.04-0.08 (0.0016-0.0031)
Top Ring End Gap, in (mm) ............... 0.30-0.55 (0.012-0.022)
Second Ring End Gap, in (mm) ............... 0.60-0.95 (0.024-0.037)
Oil Ring End Gap, in (mm) ............... 0.25-0.55 (0.010-0.022)

Tightening Torque Specs

Cylinder-head bolts ............... 190-210 Nm (140-155 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)
Oil drain plug ............... 30-40 Nm (22–30 lb-ft)
Fuel line nuts ............... 25-30 Nm (18-22 lb-ft)
Water pump bolts ............... 25-30 Nm (18-22 lb-ft)
Timing gear cover bolts ............... 20-25 Nm (15-18 ft-lb)
Injector hold-down ............... 20-25 Nm (15–18 lb-ft)

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• Cummins Engines Specs
  
• Cummins 6LTAA8.9-G3 Specs
  
• Cummins 6LTAA9.5-G1 Specs
  
• Cummins 6T-590 Specs
  
• Cummins 6T-830 Specs
  

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