Although sharing many technologies with the TDV6, the 3.6-litre TDV8 has been designed from the outset to meet the refinement, torque characteristics and off-road needs of the Range Rover. It is not just a V6 with two extra cylinders. For example, the V6 has a bank angle of 60 degrees, while the V8 has 90 degrees - the best configuration for a V8’s balance and refinement.
As with the TDV6, the TDV8 uses a revolutionary Compacted Graphite Iron (CGI) block, which has much higher tensile strength than ‘standard grey’ cast iron, better fatigue strength than aluminium, and extraordinary stiffness. Its overall advantages in weight and strength mean the block can be lighter and smaller than those of rivals, making it astonishingly compact for such a large-capacity engine.
The block’s outstanding stiffness is a major factor in the refinement of the engine. The TDV8 is one of the world’s quietest and smoothest diesels, as well as one of the mightiest. Heads are cast in aluminium. The overhead camshafts - two per cylinder bank - are hollow to reduce weight, and actuate the 32 valves through roller-finger followers and hydraulic lash adjusters. The intake camshaft is driven by a simplex bush chain, the exhaust camshaft by near-silent gearwheels. The intake manifold - made from lightweight injection moulding - and cylinder heads employ Land Rover’s intake port deactivation technology, to optimise swirl across the full engine speed range.
The new TDV8 is designed not just for day-to-day road driving and high-speed motorway or autobahn cruising, but also for river wading, dust, mud and the steep angles necessary for class-leading off-road capability. As with all Land Rover products, the new Range Rover TDV8 must be able to drive through 45-degree gradients and traverse 35-degree side slopes, as well as wade through water 500 mm deep.
The 90-degree V8 configuration means the twin turbochargers are sited low in the engine. At extreme angles, there is a risk that either turbo may be below the sump level, restricting oil flow. So a new, patent pending, vacuum lubrication system has been developed to ensure full flow of oil at all times to the critical turbochargers, even on the most severe side slopes. No other turbo V8 has anything like the all-terrain versatility of the Range Rover’s new engine.
The variable nozzle turbochargers - one per cylinder bank - have small turbine wheels, for excellent response. Their variable nozzle design boosts not only response, but also low-end torque and top-end power. No wastegate is necessary, improving refinement and boosting the progressive driving characteristics of the engine.
Common-rail injection technology improves refinement, power and economy. Fuel is injected at up to 1700 bar (more than 24,000 psi), about 30 per cent higher than in previous-generation common-rail fuel systems. Incredibly accurate Piezo injectors provide highly efficient combustion, very low particulate emissions and instant power on demand. They also reduce combustion noise, improving refinement.
Despite the phenomenal performance, this is one of the world’s quietest diesels. Noise, at both idle and full load, is extremely low.
"Compared with the outgoing Range Rover diesel, the new engine is up to 75 per cent quieter, a huge improvement," says Al Kammerer, product development director for Land Rover. "In both qualitative and quantitative measures, the new diesel is very similar to the V8 petrol engine - a tremendous achievement."
The noise levels are so low that Land Rover engineers had to target other sources of engine noise normally masked by combustion noise. Extraneous sounds are dampened by a comprehensive acoustic system, including a glass-reinforced nylon engine cover and sound-deadening rubber-mounted covers encapsulating the fuel injectors, to ensure that injection noise goes unnoticed.
Given the TDV8’s exceptional standards of performance and refinement, it would be easy for people to mistake it for a petrol engine. So Land Rover has developed a new, patented device for the TDV8 fuel filler neck, to avoid the risk of inadvertent fuelling with petrol.