Nissan's V6 masterpieces have consistently been ranked among Ward's Ten Best Engines of the World for 14 years. Nissan's new twin-turbo 3.8l V6 fitted to the Nissan GT-R is one of the world's most performance-oriented powertrains, as it has outperformed most sports cars on the Nürburgring racetrack, with an astonishing 7'29" lap time.
Now Nissan has developed a brand new, high-tech V6 diesel engine and fitted it to two of the brand's flagships, the Navara and Pathfinder 3.0 V6 dCi.
The new engine, branded the V9X, was developed to power the future of Nissans luxury off-roaders and LCVs beyond 2010, thanks to its muscular power delivery, impressive environmental credentials, quietness and smoothness.
The new engine means the Navara is the first 1-ton LCV with a V6 turbo diesel capable of delivering 550Nm of torque from as low down as 1700rpm.
The V9X 3.0-litre V6 is a clean-sheet design based on lessons learnt in development of the celebrated 2.0-litre dCi motor in Nissan's popular diesel Qashqai. The V9X has been developed in Europe by Alliance engineers in Cleon in France in line with Nissan's demands for a powerful but exceptionally refined diesel, quiet enough in use to match the high standards set by the VQ 4.0l V6 petrol engine.
The key element of the new V6 - with an unusual vee angle of 65º - is the material chosen for the engine block. After exhaustive evaluation, Compacted Graphite Iron (CGI) was selected for its ability to deliver all the strengths of cast iron, including high levels of stiffness and excellent noise absorption qualities, without the significant weight penalty of this more traditionally-accepted construction method. While CGI does make for a heavier block than one made of pure alloy, there is no need to add stiffening ribs or extra sound deadening material so the weight gain is largely offset thanks to the superior inherent qualities.
A number of significant changes have been made to the V9X compared to the 2.0-litre dCi, which helped accelerate its development. The combustion chamber, for example, has been specifically optimised to deliver improved balance between emission levels and fuel efficiency.
Engineers were able to reduce the compression to 16:1 to benefit not just economy and emissions but also noise, vibration and harshness (NVH). Internal engine friction is reduced by the use of ultra-smooth components, such as a micro-finished forged steel crankshaft.
Class-leading levels of torque and highly competitive specific power outputs are delivered thanks to the fitment of a large single turbocharger, mounted within that 65º vee of the engine, a water-to-air heat exchanger (intercooler), and the use of the latest generation of Bosch common-rail fuel injection, which incorporates 7-hole piezo injectors and operates at 1800 bar for the most precise control of engine characteristics through perfect fuelling.
V9X delivers 170kW of power in addition to that headline-grabbing 550Nm of torque, positioning it as a class leader in terms of pure power. Peak torque is achieved from as low as 1700rpm and is available all the way to 2500rpm, while as much as 500Nm is available from a mere 1500rpm. Idle speed is an exceptionally low 650rpm with none of the harsh vibrations or intrusive noise usually associated with a diesel.
The result is strong low-end performance with comfortably refined delivery and exemplary throttle response. In addition, the engine helps provide strong towing performance, with the Navara having a 3000kg limit, and the Pathfinder capable of towing 3500kg of braked trailer.
In addition to the gains made by the changes to the combustion chamber, the V9X engine also incorporates a number of innovative details. Among these is the adoption of an overcooled Exhaust Gas Recirculation (EGR) system which further reduces harmful emissions. The system incorporates an integrated exhaust gas bypass in the EGR cooler which quickly helps to achieve the optimum temperature after start-up so that the full cooling capacity can be employed. By reducing the temperature of the exhaust gas before having the catalysts process these particular pollutants, lower carbon monoxide and hydro carbon emissions have been achieved.
Equally significant is the treatment of the tailpipe emissions themselves. The V9X exhaust system comprises a metallic oxidation catalytic converter offering lower pressure loss compared to a ceramic system, making for a more efficient engine overall as less diesel is consumed.
Engine name: 3.0 V6 dCi (V9X)
Layout: V6 / 65°
Number of cylinders/valves: 6/24
Air intake system: Turbo Intercooler
Injection type: Diesel direct injection, 1800 bar double common rail, 7-hole Piezo injectors
Balancer shaft: Not necessary
Crankcase/cylinder head material: Cast Iron/Aluminium
Cylinder block material: Compacted Graphite Iron (CGI)
Displacement: 2991cm3
Bore X stroke: 84mm X 90mm
Compression ratio: 16:1
Camshaft Drive: Single stage chain
Emission control system: Catalytic converter with EGR
Maximum power: 170kw/3750rpm
Maximum torque: 550nm/1750rpm
0-100km/h: 9.30s
Top speed: 195km/h
Urban cycle: 12.7 litres/100km
Extra urban cycle: 7.6 litres/100km
Combined cycle: 9.5 litres/100km
CO2 emissions: 250 g/km
