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Cummins 6BTAA5.9-G12 Engine

The Cummins 6BTAA5.9-G12 is an inline, 4-stroke, 6-cylinder diesel engine with a total displacement of 5.9 liters. This specific G-drive variant is engineered primarily as a prime mover for medium-power stationary and mobile diesel generator sets. It features a robust structural design characterized by an integrated cylinder block and head configuration. This layout minimizes potential water and oil leakage paths while utilizing up to 40% fewer parts than equivalent engines in its class. The engine uses a forged steel camshaft and crankshaft housed in a reinforced block to handle continuous high mechanical loads. Induction is handled via a turbocharged and charge air-cooled (air-to-air) aspiration system to ensure high volumetric efficiency and rapid transient load response.

The fuel system uses a high-pressure, mechanical inline injection pump paired with a secondary governor assembly. The high-pressure unit is a BYC Beiyou P7100 mechanical injection pump. Engine speed control and stability are maintained by an integrated electronic governor system (such as SEGMA or GAC). This arrangement ensures precise steady-state speed regulation with a droop percentage of 1% to 5%, enabling tight frequency management under fluctuating electrical generator loads.

The lubrication circuit uses a pressurized wet-sump design with a gear-driven oil pump. The minimum overall lubricant capacity including the standard oil pan and full-flow combi-filter assembly is 16 liters. Oil retention is enhanced through a specialized platform-mesh honing design within the cylinder walls and advanced piston ring sealing components. The minimum allowable oil pressure to trigger engine protection devices is 100 kPa at low idle speed (700-800 RPM) and 400 kPa at governed speed. The engine uses a forced-circulation, liquid-jacket cooling design. The total coolant fluid capacity of the engine block and standard passages alone is 9.9 to 10.0 liters. Air-to-air charge air cooling lowers internal intake manifold air temperatures after the turbocharger stage to maximize thermal efficiency.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6BTAA5.9-G12
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) ............... 4.02 (102.0)
Engine Stroke, in (mm) ............... 4.72 (120.0)
Displacement, cu.in (L) ............... 359 (5.9)
Rated Engine Power, hp (kW) ............... 228-295 (170-220)
Rated Engine Speed, rpm ............... 1500-1800
Peak Torque ............... 750-950 Nm (553-700 lb-ft) at 1400-1600 rpm
Idle Speed ............... 700-800 rpm
Aspiration Type ............... Turbocharged and aftercooled
Compression Ratio ............... 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 ............... 35-75

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) ............... 41.3-45.2 (1050-1150)
Overall Width, in (mm) ............... 27.6-31.5 (700-800)
Overall Height, in (mm) ............... 41.4-49.3 (1050-1150)
Dry Weight, lbs (kg) ............... 1055-1145 (480-520)

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) ............... 0.254 (0.010)
Exhaust Valve Clearance, in (mm) ............... 0.508 (0.020)

Engine Oil and Coolant

Engine Oil Type .................. SAE 10W-30, 15W-40
API Service Classifications ......................... CI-4, CJ-4, or CK-4
Engine Oil Capacity, qts (L) .................. 13.6-16.8 (13.0-16.0)
Coolant Capacity, qts (L) ............... 21.0-26.3 (20.0-25.0)

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) ............... 4.0165-4.0177 (102.000-102.030)
Crankshaft Journal Outside Diameter, in (mm) ............... 3.2672-3.2682 (82.987-83.013)
Crank Pin Outside Diameter, in (mm) ............... 2.7160-2.7170 (68.987-69.013)
Crankshaft End Play, in (mm) ............... 0.0040-0.0130 (0.102-0.330)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3129-0.3139 (7.947-7.973)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3121-0.3131 (7.927-7.953)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.3154-0.3169 (8.011-8.049)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.3154-0.3169 (8.011-8.049)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0040 (0.038-0.102)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0023-0.0048 (0.058-0.122)
Intake Valve Spring Free Length, in (mm) ............... 1.879 (47.73)
Exhaust Valve Spring Free Length, in (mm) ............... 1.879 (47.73)
Intake Cam Height, in (mm) ............... 1.8482-1.8612 (46.945-47.275)
Exhaust Cam Height, in (mm) ............... 1.8385-1.8540 (46.697-47.091)
Piston Pin Outside Diameter, in (mm) ............... 1.5746-1.5750 (39.995-40.005)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0003-0.0007 (0.008-0.018)
Second Ring Side Clearance, in (mm) ............... 0.0027-0.0045 (0.068-0.115)
Oil Ring Side Clearance, in (mm) ............... 0.0015-0.0033 (0.038-0.085)
Top Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)
Second Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)
Oil Ring End Gap, in (mm) ............... 0.0100-0.0220 (0.254-0.559)

Tightening Torque Specs

Cylinder-head bolts ............... 190-210 Nm (140-155 lb-ft)
Main-bearing caps ............... 245-260 Nm (181-192 lb-ft)
Connecting-rod bolts ............... 75-85 Nm (55-63 lb-ft)
Flywheel bolts ............... 135-150 Nm (100-111 lb-ft)
Crankshaft damper bolt ............... 270-300 Nm (199-221 lb-ft)
Oil drain plug ............... 40-50 Nm (30-37 lb-ft)
Injector hold-down ............... 25-30 Nm (18-22 lb-ft)

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• Cummins Engines Specs
  
• Cummins 6B5.9 Specs
  
• Cummins 6BT5.9-G1 Specs
  
• Cummins 6BT5.9-G2 Specs
  
• Cummins 6BTA5.9 Specs
  

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