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Cummins 6CTA8.3 Engine

The Cummins 6CTA8.3 is a heavy-duty, 4-stroke, inline 6-cylinder diesel engine widely utilized across marine, industrial, construction, and power generation sectors. Known as a foundational part of the "Diamond Series" and its rugged design, it features a single-piece crossflow cylinder head cast from high-strength gray iron and mid-stop replaceable wet cylinder liners. This structural architecture minimizes internal components by up to 40% compared to traditional engines of similar displacement, reducing failure points and simplifying field overhauls. The engine employs a completely mechanical overhead valve train configuration driven by a forged steel camshaft and hardened helical gears, eliminating complex electronic failures and ensuring maximum durability under extreme duty cycles.

The fuel system is an entirely mechanical high-pressure injection architecture. It relies on a gear-driven Bosch (or Nippon Denso/Weifu) inline mechanical injection pump. This fuel pump functions alongside a mechanical governor (such as the RSV type) to automatically stabilize and correct engine RPM relative to varying operational loads. High-pressure steel lines channel fuel to non-electronic multi-hole injectors, delivering maximum atomization directly into the combustion chamber bowls. Clean fuel delivery is regulated through standard spin-on fuel/water separator filters.

The lubrication configuration utilizes a standard wet-sump oil pan with an integrated oil cooler. Oil circulation is pressurized through a gear-driven internal pump. System filtering relies on high-efficiency, spin-on Fleetguard full-flow filter canisters. The cooling loop handles extreme thermal stress through either an engine-mounted heat exchanger setup, a single-loop keel system, or a heavy-duty industrial radiator with an optional fan drive assembly. The system features integrated internal water jackets and conduits molded directly into the block casting.

General Technical Data

Engine Specifications

Engine Model ............... Cummins 6CTA8.3
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) ............... 5.31 (135.0)
Displacement, cu.in (L) ............... 505 (8.3)
Rated Engine Power, hp (kW) ............... 220-300 (165-225)
Rated Engine Speed, rpm ............... 1800-2200
Peak Torque ............... 900-1100 Nm (664-811 lb-ft) at 1300-1600 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) ............... 47.2-55.1 (1200-1400)
Overall Width, in (mm) ............... 29.5-35.4 (750-900)
Overall Height, in (mm) ............... 43.3-51.2 (1100-1300)
Dry Weight, lbs (kg) ............... 1430-1710 (650-780)

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 (0.305)
Exhaust Valve Clearance, in (mm) ............... 0.024 (0.610)

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) .................. 19.9-23.1 (18.0-22.0)
Coolant Capacity, qts (L) ............... 26.3-31.5 (25.0-30.0)

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) ............... 4.4882-4.4894 (114.000-114.030)
Crankshaft Journal Outside Diameter, in (mm) ............... 3.8568-3.8588 (97.962-98.013)
Crank Pin Outside Diameter, in (mm) ............... 2.9906-2.9926 (75.962-76.013)
Crankshaft End Play, in (mm) ............... 0.0051-0.0150 (0.130-0.380)
Intake Valve Stem Outside Diameter, in (mm) ............... 0.3721-0.3732 (9.451-9.479)
Exhaust Valve Stem Outside Diameter, in (mm) ............... 0.3713-0.3724 (9.431-9.459)
Intake Valve Guide Inside Diameter, in (mm) ............... 0.3745-0.3760 (9.512-9.550)
Exhaust Valve Guide Inside Diameter, in (mm) ............... 0.3745-0.3760 (9.512-9.550)
Intake Valve Stem to Guide Clearance, in (mm) ............... 0.0013-0.0039 (0.033-0.099)
Exhaust Valve Stem to Guide Clearance, in (mm) ............... 0.0021-0.0047 (0.053-0.119)
Intake Valve Spring Free Length, in (mm) ............... 2.366 (60.10)
Exhaust Valve Spring Free Length, in (mm) ............... 2.366 (60.10)
Intake Cam Height, in (mm) ............... 1.881-1.906 (47.78-48.42)
Exhaust Cam Height, in (mm) ............... 1.898-1.924 (48.22-48.86)
Piston Pin Outside Diameter, in (mm) ............... 1.7714-1.7719 (44.993-45.005)
Piston Pin to Piston Bore Clearance, in (mm) ............... 0.0002-0.0008 (0.005-0.021)
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) ............... 0.0118-0.0217 (0.30-0.55)
Second Ring End Gap, in (mm) ............... 0.0157-0.0256 (0.40-0.65)
Oil Ring End Gap, in (mm) ............... 0.0098-0.0217 (0.25-0.55)

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)
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 ............... 25-30 Nm (18-22 lb-ft)

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• Cummins Engines Specs
  
• Cummins 6C8.3 Specs
  
• Cummins 6CT8.3 Specs
  
• Cummins 6CTAA8.3 Specs
  

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