LANHAM, MD (8/1/00) - From advanced engine management components to sophisticated permanent four-wheel drive systems, Land Rover offers sport-utility vehicles that are built with state-of-the-art technology. This release provides detailed information about the technological features built into the Discovery Series II and Range Rover models. It also helps to dispel some commonly held myths about Land Rovers specifically and sport-utility vehicles in general.

ENGINE
Myth: Land Rovers do not offer contemporary engine technology.
Reality: The Land Rover V8 has been continually refined and possesses state-of-the art components.

The latest iterations of Land Rover's V8 engine, used in all Land Rover models sold in North America, have been heavily modified from the powerplant's original version. Name the part: block, pistons, camshaft, seals, even metallurgy-they've all been updated. The Land Rover V8 has gone through so many changes over the years that it is similar to the original engine only in architecture.

The latest 4.0- and 4.6-liter engines found respectively in the Discovery Series II and Range Rover models, are comprised of aluminum alloy, a material chosen for its light weight and thermal efficiency. The sides of the engine block feature special ribbing for extra strength and reduced noise, vibration and harshness (NVH) levels. Cast-iron cylinder liners provide good wear characteristics. All engine parts-including the block, pistons, camshaft, manifolds and seals-have been refined for smooth operation and low NVH levels. The Bosch Motronic 5.2.1 engine management system, employed in both versions of the engine, is state-of-the-art.

The current V8 engine's induction system consists of a three-piece intake manifold that features long tracts placed within a compact area. Combined with a dual-plenum configuration, these long intake runners speed airflow into the engine, increasing torque levels at relatively low engine speeds. Both the 4.0- and 4.6-liter engines develop their peak torque at just 2,600 rpm and offer a broad, flat band of torque throughout their rev ranges.

Why the emphasis on torque as opposed to horsepower? Because a broad band of torque at relatively low engine speeds is much more important in a sport-utility vehicle. Torque is pulling power, and both versions of the Land Rover V8 have been engineered to provide broad, usable torque. In fact, at least 84 percent (that is, 210 pound-feet) of the 4.0-liter's peak torque is available from 1,500 rpm to 4,500 rpm. For the 4.6-liter engine, at least 80 percent of the peak torque is available from 1,400 rpm to 4,500 rpm-which means that 240 pound-feet of torque is available when the engine is running barely above idle! These V8 engines offer pulling power where sport-utility drivers need it most-for merging into traffic, towing a trailer and maneuvering in low-rpm, low-traction situations.

All Land Rover V8 engines feature sequential electronic fuel-injection and advanced Bosch Motronic engine management systems. Bosch engine management optimizes all aspects of engine performance for low emissions, good fuel economy, smooth running and ample power delivery. The following list of inputs to the engine computer offers some idea of the parameters taken into account in order to control engine performance.

Engine Management System inputs

Another input, one that's specifically engineered for Land Rover vehicles, is a rough-road signal designed to tell the engine management system that the vehicle is being driven off-road. Whenever the engine computer receives a rough-road signal-supplied by the wheel-speed sensors-the computer modifies its misfire detection strategy and evaporative emissions control to allow for the rocking motion and in-tank fuel sloshing that occurs during off-road driving.

The ignition system used in Land Rover's V8 engines is distributorless. But rather than using a separate coil for each platinum-tipped spark plug, the Land Rover system employs two twin-ignition coils (for a total of four coils) and a "wasted spark" strategy. This surprisingly simple concept fires two spark plugs simultaneously. One ignites the fuel/air mixture at the optimum time in the appropriate cylinder; the other fires without effect during the exhaust stroke of a separate cylinder. This system works just as effectively as an eight-coil system but is simpler because it only uses four coils.

Both Discovery Series II and Range Rover models use ZF electronically controlled automatic transmissions (HP22 on Discovery Series II, HP24 on Range Rover) that incorporate engine/transmission networking and a locking torque converter. The transmission's electronic control unit uses sensors for engine rpm, vehicle speed and throttle position, among other inputs. In total, the unit receives 15 inputs.

The electronic control unit of each ZF transmission continuously communicates with the engine's control unit. In fact, in the Discovery Series II, a Controller Area Network operates at 500,000 baud (consider the 56,000-baud rate at which many PC modems operate!). As such, the two control units can compare their operating parameters in real time for smoother shifts, faster warmups and noticeable responsiveness.

PERMANENT FOUR-WHEEL DRIVE AND ELECTRONIC TRACTION CONTROL
Myth: Sport-utility vehicles have only recently offered high-tech electronic traction control systems.
Reality: The 1993 Range Rover was the first SUV to feature electronic traction control and, since 1999, both Range Rover and Discovery Series II have featured four-wheel Electronic Traction Control (4ETC), a system that supplements the vehicles' permanent four-wheel drive systems.

Land Rover's permanent four-wheel drive system is instantly ready to take advantage of all available traction-without the driver having to shift gears or throw levers. As long as at least one wheel can attain even a small amount of grip, Land Rover's four-wheel drive system will find and make use of it. There are a few differences between the Range Rover and Discovery Series II permanent four-wheel-drive systems.

Inside Range Rover's two-speed transfer gearbox, there's a center differential that allows easy maneuvering while directing engine torque to all four wheels-plus a viscous coupling unit (VCU). The VCU limits front-to-rear slippage by allowing only a limited difference in speed between the front and rear output shafts. As this speed difference increases, drag inside the coupling increases, progressively transferring more drive to the front axle until the unit reaches a state of virtual lock, sending 50 percent of the torque to the front axle and 50 percent to the rear. Discovery Series II uses a similar three-differential setup, but it does not have a viscous coupling unit. Instead, Discovery Series II relies on different programming in its four-wheel Electronic Traction Control (4ETC) system to limit front-to-rear slip.

The 4ETC system in both Discovery Series II and Range Rover models continuously monitors and compares the speeds of each wheel, plus the difference in speed between the front and rear driveshafts. If 4ETC detects a spinning tire, the system is designed to slow the wheel automatically by pulsing an individual brake. This action slows down the spinning so the wheel can get a better grip, and also forces torque across the axle to the slower-running wheel with greater traction.

4ETC is fully operational in all high range and low range gears. On Range Rover models, the 4ETC system functions at speeds of up to 31 mph. On Discovery Series II, the system operates fully at speeds up to 31 mph and in partial mode up to 62 mph. Above the threshold speed in both models, the fundamental permanent four-wheel-drive system optimizes traction. Since 4ETC uses some of the same sensors as the Anti-lock Braking System (ABS), the two systems cannot operate simultaneously-logically, drivers want the vehicle to either stop or go. Therefore, applying the brakes will disable the 4ETC system.

The engagement strategy for 4ETC is different on Range Rover than Discovery Series II due mainly to the presence of a VCU in Range Rover. And compared to competitive systems, the Land Rover 4ETC engagement strategy is more aggressive and uses the system's electronics to their fullest potential to help control wheel spin. Land Rover's 4ETC system is built with everything from engine electronics to the choice of tires in mind and is fully integrated into the vehicle's entire powertrain design philosophy.

Both Discovery Series II and Range Rover have two-speed transfer gearboxes. While Discovery Series II uses a separate shifter for the transfer gearbox, Range Rover's H-gate shifter combines the operation of the main gearbox and the transfer gearbox in one mechanism. The H-gate is the most convenient method of selecting low range-and is still unique in the automotive industry.

CONSTRUCTION
Myth: Unitized body construction (versus body-on-frame) is the only truly modern way to build a sport-utility vehicle.
Reality: Land Rover's fully boxed-steel frame and monocoque inner structure are state-of-the-art, and offer high strength and rigidity.

A heated discussion can ensue if one brings up the subject of unibody versus body-on-frame construction with hard-core SUV enthusiasts. In reality, either system can be effectively engineered to provide a strong, durable and capable vehicle. What few people realize is that Range Rover and Discovery Series II actually use both systems.

The backbone of every Range Rover and Discovery Series II is a fully boxed and seam-welded perimeter frame with large, boxed or tubular crossmembers. This strong foundation can easily handle off-road stresses and towing. These fully boxed frames are constructed of micro-alloyed steel. A boxed-section frame offers greater strength than the C-section frames used in many other SUVs. Land Rover frames, which are up to 4 mm thick, are seam-welded along their entire length.

In addition to the frame, both Land Rover models also employ an inner body-cage, constructed in much the same way as most typical unitized bodies. Finally, there are the outer body panels, constructed of either aluminum-alloy sheet metal or double-galvanized steel.

This complex body cage structure has been designed in parallel with the suspension for handling ability, roll stiffness, steering precision and occupant protection, as well as low NVH levels. And the body mounts that bring all the pieces together-10 in Range Rover and 14 in Discovery Series II-have been specifically engineered to isolate the passenger cabin from noise.

AIR SUSPENSION SYSTEMS
Myth: Several SUVs offer air suspension, and the systems are all pretty much the same.
Reality: Range Rover's Electronic Air Suspension (EAS) system is one of the most sophisticated systems available, offering five modes of operation and both automatic and manual control.

Using computer-controlled air springs located at each wheel, Range Rover's EAS system automatically levels the vehicle, no matter what the load, and offers five modes of operation with an adjustable height range of 5.3 inches.

The air springs are adjusted automatically via an on-board compressor, and are computer controlled, based on data received from a driver-selectable switch and height sensors mounted at each corner of the vehicle. An air distribution box mounted to the left of the engine houses a compressor, the solenoid valve block and the solenoid driver pack. The EAS system's electronic management system (complete with self-diagnostics) controls system pressures and regulates airflow to and from the individual air springs. The compressor even has intake and exhaust filters to keep the system clean.

EAS can lower the vehicle when stopped, for easy access. It also automatically lowers the vehicle at highway speeds for even greater stability and improved aerodynamics. When traversing difficult terrain, EAS can be called upon to raise the Range Rover higher, and will even help a tire reach for additional grip under exceptionally severe off-road conditions. Any of the driver-selectable modes can be locked into place using the inhibit switch-for example, drivers who want to keep the vehicle in Low mode even at lower-than-highway speeds can select that mode and inhibit any other mode.

The Electronic Air Suspension system's five operating modes are:

Discovery Series II's optional Self-Leveling Suspension (SLS) is a simpler system than Range Rover's EAS system. SLS uses air springs at the rear while retaining coil springs in front. Unlike the Range Rover system, it does not have an air reservoir-it relies on an electric air compressor to increase ride height-so changes in suspension height take place at a slower rate. SLS offers automatic load-leveling and three modes of operation. Standard mode holds the vehicle at normal ride height. Off-road/High mode is 1.6 inches above Standard mode and is driver selectable at speeds below 19 mph. Extended mode, like that of Range Rover's EAS, engages automatically if the vehicle becomes high-centered.

ACTIVE CORNERING ENHANCEMENT
Myth: The suspension systems SUVs employ aren't very sophisticated.
Reality: Discovery Series II's optional Active Cornering Enhancement system is an award-winning active anti-sway bar system that is exclusive to Land Rover.

Two of Land Rover's initial goals for Discovery Series II were reduced vehicle body lean on-road and plenty of axle articulation off-road. These goals at first seem to be mutually exclusive. But Active Cornering Enhancement (ACE) achieves both objectives. ACE is a unique Discovery Series II option that measures vehicle speed and lateral "g" acceleration and automatically adjusts special two-piece roll-control modules during cornering. The roll-control modules replace conventional anti-sway bars.

Anti-sway bars are designed to limit body lean in curves by restricting the overall movement of suspension components. Making the anti-sway bars too thick increases the harshness of the ride over bumps and limits the ability of the axles to articulate-travel in opposite tilt relative to each other and the vehicle. On ACE-equipped vehicles, two accelerometers-one mounted in the vehicle's headliner and the other near the floor-detect cornering forces before the body begins to lean, making the system truly active, not reactive. These sensors instruct the ACE computer to apply hydraulic pressure to a set of actuators, one on each anti-sway bar. These actuators-basically hydraulic cylinders with multiple links-apply torque to the anti-sway bars, giving them added ability to counteract vehicle body lean. It all happens in a flash. ACE can build up sufficient hydraulic pressure to counteract 1.0 g of lateral acceleration in less than 130 milliseconds.

The system is designed to virtually eliminate body lean up to about 0.4 g of lateral acceleration. Above that value, the system progressively allows more body lean to give the driver positive feedback on the vehicle's handling. This results in dramatic stability in corners, a definite benefit to driver control and passenger comfort. It also aids steering response since it keeps the vehicle's body more level to the road. And unlike conventional anti-sway bars, ACE does not affect spring rates over bumps. ACE is even sophisticated enough to vary its action depending on whether the road is rough or smooth.

Off-road, the system goes into a different mode. At speeds below about 25 mph in low range, when the accelerometers determine the vehicle is driving off pavement, the system eliminates ACE assistance, allowing the suspension to offer additional wheel travel (as if the anti-sway bars had been eliminated.) This additional wheel travel helps the vehicle's body maintain a consistent attitude, parallel to the ground.

HILL DESCENT CONTROL
Myth: You have to be a real expert driver to control an SUV on a steep downhill trail, especially if the surface is loose or slippery.
Reality: While expert training is required before attempting any serious off-road driving, Discovery Series II's standard Hill Descent Control (HDC) system takes the trepidation out of steep downhill trails.

Hill Descent Control (HDC), standard on Discovery Series II, is an ingenious system that can help the vehicle safely descend inclines. HDC uses the vehicle's brakes as necessary to supplement the normal engine braking that occurs naturally when first gear, low range is selected. HDC is activated on Discovery Series II by shifting into low range and pushing the yellow button located on the dashboard. As with 4ETC, applying the brakes cancels out the operation of HDC.

The HDC system detects the degree of the downhill gradient and applies the brakes on the downhill axle. It works in forward and reverse gear. HDC determines the amount of brake pressure to apply-and the appropriate speed to which the vehicle should be restricted-based on the gear selected and the amount of throttle applied.

Its program will vary the vehicle's downhill speed from between 3.5 mph and 7.5 mph with zero throttle. With throttle pressure applied, HDC will vary vehicle speeds all the way up to 31 mph, at which point it will progressively decrease its action. HDC can even compensate for extra rough roads. Hill Descent Control does not operate continuously, but rather activates only as needed.

When HDC is operating, the vehicle's brake lights will illuminate. The system will even work in neutral for about one minute while giving the driver ample warning-via a flashing light and an audible tone-to select a gear before it begins fading out.

With zero throttle, HDC speeds (all in low range) are: