COX CXO300 300 HP diesel outboard

The CXO300 diesel outboard has been designed and built specifically for marine use – the first of its kind. As one of the most powerful diesel outboards brought to the market, the CXO300 has been developed to be compatible with existing industry standards – making it as easy to install on a wide range of vessels as any gasoline outboard. The diesel outboard motor takes standard pump diesel, has a standard outboard fitting layout, and is compatible with all Seastar EPS steering.

The CXO300 is commercially rated, giving you industry assurance, but also has a recreational warranty of 5 years and a commercial warranty of 18 months or 1500 hours.

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Engine block and head

  • 60 degree V8
  • Aluminium alloy block, heads and ladder frame
  • Quad camshafts, four valves per cylinder

Engine mounting

  • Standard outboard fitting layout
  • 6-bolt mounting with multi-hole adjustment
  • 30″ transom spacing (28.5″ with steering limits)

Fuel system

  • Electronically controlled high-pressure common rail injection
  • On-engine fuel filtration and cooling

Air inlet and exhaust system

  • Twin turbochargers with electronic boost control
  • Water-to-air charge cooling
  • Air filters with replaceable inserts


  • 90-degree spiral bevel gear drive
  • All outboard offer standard and counter rotating capability, programmable through the ECU

Cooling system

  • Thermostatically regulated raw water cooling
  • Solid impeller low-maintenance water pump

Oil system

  • Closed crankcase ventilation

Electric system

  • Drive-by-wire power and shift control
  • 12V electrical system
  • 100A flywheel-integrated marine alternator
  • Automatic integrated fuses


  • Maximum propeller diameter 16″
  • 19 tooth 1.25″ propeller spline


  • Seastar electronic throttle
  • Seastar joystick
  • Coastkey Keyless key fob / wireless MOB technology
  • Compatible with NMEA 2000
  • Murphy Powerview displays – 4.8”/7”/10”/12” screen sizes
  • Compatible with all Seastar EPS steering


CXO 300 technical spec

Engine Designation CXO300
Propeller shaft power, kW (hp) 224 (300)
Engine propping speed, rpm 3700-4000
Displacement, L ( 4.4 (266)
Weight, kg (lb) 393 (866)
Number of cylinders 8
Bore/stroke, mm (in.) 84 (3.3) / 98.5 (3.9)
Compression ratio 16:1
Ratio 1 (Propeller speed) 1.23:1 (3259)
Ratio 2 (Propeller speed) 1.46:1 (2739)
Peak torque, Nm ( 650 (479)
Aspiration Twin-turbo
Shaft Length, inch(mm) 25”(635) / 30”(762) / 35”(889)
Emission compliance EPA 3, IMO 2, RCD 2
Rating Light-duty commercial
Trim range -4° to +16°
Tilt range 71°
Gear Oil Spec SAE 80W90, API GL-5
Powerhead Oil Spec Min standard – fully synthetic API CI-4/ SAE 10W40 or 5W40
Propeller spline spec 1.25” shaft / 19 tooth
Colour options Black / White