POWERTRAIN Globally, three engine choices are offered on the Discovery 3, headed by a 4.4-litre petrol V8, specially adapted from the engine used by Jaguar. Also new is an outstanding TDV6 turbodiesel, one of the most sophisticated diesel engines in the world and expected to be the best-seller in Europe (not available in North America).…

Globally, three engine choices are offered on the Discovery 3, headed by a 4.4-litre petrol V8, specially adapted from the engine used by Jaguar. Also new is an outstanding TDV6 turbodiesel, one of the most sophisticated diesel engines in the world and expected to be the best-seller in Europe (not available in North America). Selected markets will also take a second petrol unit, a smooth, torquey and durable 4.0-litre V6.

A state-of-the-art ZF ‘intelligent shift’ electronically controlled six-speed automatic gearbox is available with all engines. In addition, a ZF six-speed manual transmission is available with the diesel engine, and is likely to prove especially popular in mainland Europe.

The top-of-the-range engine in the Discovery 3 is a Jaguar-derived V8. The most powerful engine ever fitted to a production Land Rover, this 4.4-litre unit gives superb performance both on-road and off. This quad-cam (double overhead camshafts per bank) 32-valve unit is one of the world’s lightest V8s, owing to its compact dimensions and its employment of lightweight aluminium alloy block and heads.

For Land Rover use, water-proofing, oil circulation, dust-and-mud protection and breathing were all modified, to cope with the additional challenges of climbing mountains and wading rivers. The engine ‘mapping’ has also been revised, to serve up more low-end torque, and the bore size has been increased from 86 to 88mm. The upshot is a larger capacity – 4.4 litres as opposed to 4.2 in Jaguar guise.

Maximum power is 220kW. Though this is slightly less than the equivalent engine used in the Jaguar XK, XJ and S-Type, maximum power is developed at lower revs, 5500rpm rather than 6000. Torque has been increased, and is also delivered at lower revs: 425Nm at 4000rpm.

The engine is not only light, but it is also renowned for its thermal efficiency. This improves economy, and helps with warm-up times and driving behaviour. The engine uses an electronic throttle and Variable Camshaft Phasing (VCP) – which automatically and continuously controls valve timing according to driving demands and outside temperature.

Oil capacity has been significantly increased, from 6.8 litres to 8.6 litres, to cope with the need to supply oil even at the extreme driving angles a Land Rover may face. The oil pump is new, for improved delivery of the lubrication, and the front crank oil seal is also modified, to guard against ingress from water, mud or slurry during wading or other off-roading conditions.  The aluminium oil sump is new, and engine ancillaries are repositioned as high as possible – to prevent damage when off-road.

The new high-technology TDV6 turbodiesel for the Discovery 3 is a sister engine to that recently launched in the Jaguar S-Type, to great acclaim.

The unit uses common rail technology and operates at even higher pressure than most common rail injection systems – about 25 per cent greater than average – benefiting performance, economy, refinement and emissions. Maximum power is 140kW at 4000rpm and maximum torque is an enormous 440Nm, developed at only 1900rpm.

Apart from its high injection pressure, other technological innovations include the use of a compacted graphite iron (CGI) engine block. It is one of the first uses of this material in volume engine production. CGI is stronger, stiffer, lighter and more durable than cast iron – from which diesel engine blocks are usually manufactured.

This inherent stiffness helps driving refinement, and its strength and lightness allow the engine to have less mass and smaller dimensions than a traditional V6 turbodiesel. The stiffness and strength also remove the need for cylinder liners: the cylinders are bored directly into the block casting, saving further weight. The cylinder heads are pressure die cast in aluminium alloy, and each carries two overhead camshafts operating four valves per cylinder. The camshafts are driven by a flexible belt coated in PTFE to reduce friction. To increase both reliability and precision, the camshaft belts drive no other system.

Unique to its Land Rover application, the TDV6 turbodiesel has an aluminium ladder-frame at the bottom of the crankcase, to improve rigidity. Its baffle plates prevent oil foaming and surge when off-road. Attached to the ladder-frame is a pressed steel sump, also unique to Land Rover. The oil pick-up point is optimally designed to operate at acute off-road angles.

The TDV6 turbodiesel runs with a compression ratio of 17.3:1, relatively low for a diesel engine. This reduces heat build-up in the piston bowl, improving fuel burning efficiency, and reducing fuel consumption and emissions. The low compression ratio also reduces engine noise.

The inlet manifold is made from composite material and is moulded integrally with the cam covers. It is isolated from the cylinder heads by an elastomeric material to reduce vibration.

There are two inlet ports for each cylinder. One is a ‘filling’ port, designed to get as much air as possible into the cylinder, while the other is a helical ‘swirl’ port to generate the vortices necessary for optimum fuel combustion. In certain part-load conditions, the engine management system closes the ‘filling’ port to increase the swirl effect.

This alters the combustion characteristics, reducing emissions and noise. The engine control unit is also unique to Land Rover and takes information from more than 20 sensors around the engine.

Turbocharging comes from a single KKK unit for optimum torque (the equivalent Jaguar engine has twin turbochargers) fully sealed to suit wading. The turbocharger uses an electronically controlled Variable Nozzle Turbine which ensures that air delivery is optimised by altering the angle of the turbine vanes.

It effectively widens the turbine inlet at low speed to improve torque and narrows it at high speed for better power response. The engine is equipped with a glow plug in each cylinder to assist in cold starts.  The TDV6 turbodiesel also meets EU3 emissions legislation, and has the potential to satisfy all known future legislation.

Available only in selected markets, the Discovery 3’s gutsy and smooth 4.0-litre V6 petrol engine offers good performance and economy. Maximum power is 156kW – 13 per cent more than the 4.0-litre V8 engines of the outgoing Discovery model. Maximum torque is a substantial 360Nm.

The Ford-derived engine uses a cast iron block and aluminium alloy heads. The crankshaft is counter-balanced for extra refinement.

Extensive modifications for Land Rover use include a die-cast aluminium ladder-frame on the bottom of the block to stiffen the structure, with baffle plates to stop surge and oil foaming. The revised sump includes a new oil pick-up pipe to improve lubrication at all angles. The alternator, air conditioning compressor and power steering pump are all unique to Land Rover, and are positioned as high as possible to keep out of harm’s way during extreme off-roading.

A new, cast aluminium variable-tract inlet manifold has been developed for the Discovery 3. Controlled by a new engine management system, it improves torque and driving characteristics. The lower profile manifold also helps under-bonnet packaging. The electronically controlled throttle regulates torque delivery as efficiently as possible. It is also linked to Land Rover’s patented Terrain Response system, and regulates engine response accordingly. Oil seals have also been changed, to improve water- and dust-proofing.

Six-speed gearboxes, including ‘intelligent shift’ automatic. For the Discovery 3, petrol engine vehicles come exclusively with the advanced, six-speed ZF automatic transmission. For TDV6 models, there is a choice of this automatic or a six-speed manual gearbox.

The ZF 6HP26 transmission is one of the most advanced automatic transmissions in the world. As well as offering normal automatic operation, the gearbox offers a ‘sport’ mode that alters the timing of gear shifts and throttle response. It also features ‘Command Shift’, giving the driver full manual control of gear changes. In high range, this will protect the engine by automatically changing up or down to prevent over-revving or stalling. In low range, this is overridden to allow move-off in a higher gear, which can be useful in slippery conditions.

The gearbox also analyses road conditions and each individual’s unique driving style, automatically tuning its response accordingly.

The case is unique to Land Rover, and is especially stiff. The sump is also unique. The gearbox electronic control unit is housed within it, for extra protection. This communicates, via a high-speed link, with the Terrain Response system.

The manual gearbox, available only on the diesel model, is also manufactured by ZF. This six-speed unit, with a unique casing and full compatibility with Terrain Response, is likely to be especially popular in mainland Europe, where manual diesel vehicles dominate the 4×4 market.

The two-speed transfer box features an easy-to-use electronic shift, to move into low range (for off-road) or high range (for on-road). The change can be made on the move.

For added traction, the centre differential is locked electronically when conditions require.

A lockable centre differential is a feature offered only on serious off-roaders, and enables the vehicle to crawl, at low speed, over difficult terrain with more stability and less slip.

An electronically controlled locking rear differential (known as an ‘E-Diff’) is also available with Terrain Response. Locking of the rear differential is controlled by an electronic control unit linked to the operation of the centre differential.

All three differentials used in the Discovery 3 – forward, centre and rear – are unique to the vehicle. They are mounted directly onto the chassis, a move which is designed to maximise ground clearance for improved off-road agility.

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