Spotlight: Cox CXO300 diesel outboard engine

esigned for commercial and recreational use, Cox says the CXO300 is a “new generation of diesel marine technology, offering a high-powered diesel outboard to the marine market”.

Cox’s 4.4-litre twin-turbo V8 engine has been years in the development. However, while power is rated at 300hp, it’s the relatively wide and flat diesel engine torque curve available from low revs where burning oil rather than petrol shines.

And there’s a rush of it; 650Nm from 2250-3000rpm. In contrast, Ilmor has launched a new 6.2-litre V8 inboard petrol engine producing 650Nm, but from 4000rpm, and that’s using premium unleaded fuel.

The operating speed of this engine is very different to conventional petrol equivalents, with the maximum revs of the Cox CXO300 peaking at just 4000rpm compared with 6000rpm for the spark ignition equivalent.

The Cox CXO300 is built using a lightweight aluminium alloy block, heads and ladder frame. It uses direct fuel injection and quad-cam technology with four valves per cylinder to precisely set the ignition cycle  for maximum fuel efficiency or performance.

It also uses twin turbochargers with electronic boost control, as well as water-based intercoolers to make the air entering the cylinder more dense.

The Cox CXO300 is able to restrict its torque at low revs to prevent the propeller from overpowering and cavitating, resulting in reduced hole shot performance.

The outboard engine is fitted with Dometic fly-by-wire shift and throttle controls that give more precise control to the helm, and a 100-amp flywheel-integrated marine alternator.

Dometic also supplies a joystick control system for the Cox CXO300, while CoastKey provides the engine’s keyless start system as well as a man overboard system that shuts down the engine if the wireless key is not near the helm.

Dometic can also provide electric steering for the Cox CXO300 to replace the default hydraulic setup.

Starting the Cox CXO300 is just like any other diesel vehicle, meaning you will have to wait for the outboard engine’s glow plugs to warm up before turning it over.

If you plan on replacing your existing petrol-powered outboard engine with the Cox diesel, the decision is an easy one, as it uses six standard bolt holes with 762mm spacings between engines when mounted side-by-side on the transom.

The Cox CXO300, available via Melbourne-based Power Equipment, is yet to launch on the Australian market. Cox claims the diesel outboard engine will deliver up to three times the operational life of an equivalent petrol outboard engine.

Pricing is yet to be announced, but in other markets the diesel engine is roughly double the cost of an equivalent petrol-powered version. The engines are available in either black or white.

In overseas markets, Cox offers a five-year, 1500-hour warranty on its engines for recreational use.

Specifications
Model: Cox CXO300
Pricing: N/A
Engine type: Four-stroke quad overhead cam, 32-valve
Cylinders: 60-deg V8
Fuel management: EFI, twin-turbo
Weight: 393kg
Displacement: 4400cc
Bore x stroke: 84mm x 98.5mm
Compression ratio: 16:1
Maximum output: 300hp @ 3500rpm
Operating range: 3700rpm – 4000rpm
Shaft length: 635mm (25-inch)/762mm (30-inch)/889mm (35-inch)
Alternator: 12V/100A
Trim method: Power trim/tilt
Gear ratio: 1.23:1/1.46:1
Recommended fuel: Diesel
Oil capacity: N/A
Counter-rotating: Yes
Servicing: Annually (or every 100 hours after first service)
Emissions rating: EPA 3-star
Warranty: N/A