Extremely compact in size, the D4-225 inboard diesel engine features all the benefits of the larger D6. Its power is matched by exceptionally low sound, vibrations and exhaust emissions. The reverse gear has been specially developed for the D4 enginesgiving the benefits of smooth, electrical shifting.

The basic design
The D4-225 is a 4-cylinder marine diesel engine with common rail high-pressure fuel injection, double overhead camshafts, 4 valves per cylinder, turbocharger, aftercooler and integrated balance shafts. The displacement is 3.7 litres.
It is extremely compact considering its large swept volume, high output and unique marine torque.

Common rail, 4-valve technology and turbo
The fuel system is electronically controlled common rail high-pressure fuel injection, working at a pressure of 1,600 bars. In combination with turbo, 4-valve technology and a large swept volume, it ensures superior fuel efficiency. The result is a combination of really high power and low fuel consumption with truly minimal emissions of exhaust fumes and sound that are impossible to achieve with traditional engine technology.

Extremely compact
The engine is extremely compact considering its large swept volume and high power output. With the rear end transmission driving the high-pressure injection pump and the camshaft, a high degree of integrated systems, a high-efficiency aftercooler, a marinization performed with few hoses, and a fully symmetric engine, the package is extremely compact making it possible to install more power in the engine room.

More comfort
Low noise and minimal vibrations are high-priority properties of the D4. The engine blocks are cast in a single die and are extremely robust. A ladder frame is placed between the engine block and crankcase to reinforce and further stiffen the construction. All of these factors contribute to really low vibration and sound levels.

The frame is provided with two balance shafts. Their function is to take care of the free mass force from a 4-cylinder engine.

Low emissions
The common rail system in combination with an advanced combustion system sets a new standard for minimizing exhaust emissions.

The D4-225 is a modern, low-emission engine that complies with the emission requirements introduced in the EU and USA as from 2006. Start-up and acceleration smoke is reduced to a minimum.

EVC – Electronic Vessel Control
EVC with electrical shift and throttle is the new common platform for engine and driveline control, instrumentation, accessories and efficient servicing. It offers a higher level of integration in your boat: electrical shift and throttle for smooth and safe control, a complete new range of easy-to-read, data link gauges, a large LCD display and much more, everything in just one CAN cable.


115 amp alternator
Modern boats tend to carry more and more power-consuming features such as navigators, autopilots, fridges, etc. The D4 feature a powerful 115 amp marine alternator with a Zener diode to protect the system from peak voltage and an integrated charging regulator with battery sensor for efficient charging of single or multiple battery banks.

Easier Service
The engine has the following features for easier service:
- Top mounted oil filter (easy accessible) with a closure
valve, no oil spillage when replacing the filter.
- Hydraulic lash adjusters for automatic valve clearance
, no manual adjustment are needed.
- Oil deep-stick on both sides of the engine for easy access. - The camshafts are driven by a cam-chain equipped by an
automatic chain tensioner.
- The engine is prepared for assembling a stationary oil
pump for easier change of oil.

Specially developed reverse gear
To match with the characteristics of the D4 engine, the hydraulic shifting mechanism and a gear technology that uses bevel gears throughout the gear train, we have developed a complete package for high torque, operational reliability and reduction of engine noise and vibrations.

The combination of 8° down angle, large drop centre and small dimensions makes optimized installation possible. V-drives are also available.

In order to get full benefit of the EVC-system, the reverse gear is equipped with an electrical shifting valve.