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Cummins 4BTA3.9-G11 Engine

The Cummins 4BTA3.9-G11 is a rugged, 4-stroke, heavy-duty industrial diesel engine designed primarily for generator set (G-Drive) applications. Utilizing a reliable inline 4-cylinder layout, this 3.9-liter engine features an integrated block and cylinder head design that minimizes the structural footprint while significantly reducing the risk of coolant and oil leaks. By engineering approximately 40% fewer parts than standard comparable engines, Cummins minimized component complexity and decreased overall mechanical failure rates. A combination of a Holset wastegated turbocharger and a jacket-water aftercooler (JWAC) ensures fast load responses, high power density, and excellent thermal efficiency under demanding heavy-load conditions. Cylinder configuration incorporates a bore of 102 mm (4.02 in) and a stroke of 120 mm (4.72 in).Total engine displacement measures 3.9 liters (239 cubic inches).

Fuel System: Employs a fully mechanical, electronic-governed direct injection system utilizing a BYC PB-series row-type injection pump. Fuel metering and engine speed regulations are managed via an integrated electronic governor control that guarantees steady-state governor regulation fluctuations stay at or below 5%. The high-pressure injection lines feed mechanical injectors directly into the combustion bowls, establishing an electronics-free core injection pathway that resists lower-grade diesel fuel variations.

Total lubrication system capacity requires 11 liters of engine oil, encompassing both the structural oil sump and primary filters. Oil pressure ranges from a minimum allowable limit of 300 kPa (44 psi) at low idle speed to a governed maximum of 450 kPa (65 psi) at operational engine speeds. Cylinder walls are treated with specialized platform mesh honing alongside advanced piston ring geometries to maintain strict boundary lubrication control and suppress structural oil consumption.

Cooling System: Forced liquid-circulation architecture utilizing an engine-driven water pump. Charges intake air using an integrated air-to-water intercooler (Jacket Water AfterCooled - JWAC) system tied directly to the main cooling jacket loop. Designed to interface with tropical-grade radiators to maintain heat rejection thresholds during continuous heavy-load conditions.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 4BTA3.9-G11
Engine Type ............... 4-cycle inline 4-cylinder direct injection turbocharged liquid-cooled diesel
Number of Cylinders ............... 4
Cylinder Arrangement ............... In-line
Engine Bore, in (mm) ............... 4.02 (102.0)
Engine Stroke, in (mm) ............... 4.72 (120.0)
Displacement, cu.in (L) ............... 239 (3.9)
Rated Engine Power, hp (kW) ............... 67-120 (50-90)
Rated Engine Speed, rpm ............... 2200-2500
Peak Torque ............... 300-450 Nm (220-332 lb-ft) at 1400-1600 rpm
Idle Speed ............... 750-850 rpm
Aspiration Type ............... Turbocharged and aftercooled
Compression Ratio ............... 16.5:1-17.5:1
Firing Order ............... 1-3-4-2
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
Fuel System Control ............... Mechanical
Governor Type ............... Mechanical
Fuel Injector Type ............... Multi-hole
Fuel Type ............... Diesel Fuel

Dimensions and Weight

Overall Length, in (mm) ............... 33.5-39.4 (850-1000)
Overall Width, in (mm) ............... 25.6-31.5 (650-800)
Overall Height, in (mm) ............... 35.4-39.4 (900-1000)
Dry Weight, lbs (kg) ............... 750-840 (340-380)

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, CK-4
Engine Oil Capacity, qts (L) .................. 9.5-12.6 (9.0-12.0)
Coolant Capacity, qts (L) ............... 12.6-16.8 (12.0-16.0)

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 3000 hours
Drain water separator ............... As required
Belt inspection ............... As required

Service Specifications

Cylinder Bore Inside Diameter, in (mm) ............... 4.0161-4.0177 (102.000-102.040)
Crankshaft Journal Outside Diameter, in (mm) ............... 3.2661-3.2681 (82.960-83.010)
Crank Pin Outside Diameter, in (mm) ............... 2.7150-2.7169 (68.960-69.010)
Crankshaft End Play, in (mm) ............... 0.0040-0.0170 (0.102-0.432)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3134-0.3142 (7.960-7.980)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3126-0.3134 (7.940-7.960)
Intake Valve Guide Inside Diameter (Installed), in (mm) ............... 0.3157-0.3169 (8.020-8.050)
Exhaust Valve Guide Inside Diameter (Installed), in (mm) ............... 0.3157-0.3169 (8.020-8.050)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0015-0.0036 (0.038-0.091)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0025-0.0046 (0.064-0.117)
Intake Valve Spring Free Length, in (mm) ............... 2.150 (54.61)
Exhaust Valve Spring Free Length, in (mm) ............... 2.150 (54.61)
Intake Cam Height, in (mm) ............... 1.831 (46.51)
Exhaust Cam Height, in (mm) ............... 1.819 (46.20)
Piston Pin Outside Diameter, in (mm) ............... 1.5744-1.5752 (39.990-40.010)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0002-0.0007 (0.005-0.018)
Second Ring Side Clearance, in (mm) ............... 0.0016-0.0033 (0.040-0.085)
Oil Ring Side Clearance, in (mm) ............... 0.0012-0.0030 (0.030-0.075)
Top Ring End Gap, in (mm) ............... 0.0114-0.0228 (0.290-0.580)
Second Ring End Gap, in (mm) ............... 0.0346-0.0539 (0.880-1.370)
Oil Ring End Gap, in (mm) ............... 0.0110-0.0303 (0.280-0.770)

Tightening Torque Specs

Cylinder head bolts ............... 160-180 Nm (118-133 lb-ft)
Main bearing caps ............... 150-170 Nm (111-125 lb-ft)
Connecting rod bolts ............... 70-85 Nm (52-63 lb-ft)
Flywheel bolts ............... 180-220 Nm (133-162 lb-ft)
Crankshaft pulley bolt ............... 200-240 Nm (148-177 lb-ft)
Glow plugs ............... 10-15 Nm (7-11 lb-ft)
Oil drain plug ............... 30-40 Nm (22-30 lb-ft)
Injector hold-down bolts ............... 25-30 Nm (18-22 lb-ft)

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• Cummins Engines Specs
  
• Cummins 4B3.9-G2 Specs
  
• Cummins 4B3.9-G11 Specs
  
• Cummins 4BT3.9-G2 Specs
  
• Cummins 4BTA3.9-G2 Specs
  
• Cummins 4BTAA3.3-G11 Specs
  
• Cummins 4BTAA3.9 Specs
  

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