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01/03/2011
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The new Range Rover Evoque will offer drivers both on-road excellence and off-road adventure, in a package that addresses the push for lower CO2 emissions, as Ian Adcock reports.
Four decades have passed since the original Range Rover broke cover. Spen King's radical four-wheel drive design created a new vehicle sector that has spawned imitators around the world and there are few manufacturers – apart from top-end luxury and supercar brands – that don't have an SUV within their product portfolio.
It could be claimed that, while the Land Rover and Range Rover brands have stubbornly clung to their core DNA of engineering vehicles that are peerless off-road performers, rivals have compromised that for on-road superiority. That has changed with the latest generation of Land Rover and Range Rover models. But what has also changed is the drive to reduce CO2 emissions. Four-wheel drive systems are heavy and consume energy; to be able to compete in the modern world of eco-motoring, both brands have to offer more efficient models.
Land Rover now sells a front-wheel drive Freelander and, in the Evoque, Range Rover is offering its customers a smaller, lighter model that will also be available in front-wheel guise, as well as part-time, all-wheel drive. It will still deliver class-leading, off-road ability, if customers want to do more than simply bump up a kerb when parking in crowded urban streets.
"We wanted a product that was dynamic, fun to drive, but still have the expected Range Rover credentials for off-road ability, refinement and plushness, but make it a sportier, dynamic vehicle. That's quite a significant departure in engineering for a Range Rover product," says David Mitchell, chief programme engineer, and the reason why he and his team evaluated cars such as the Audi TT and A3, Mini and BMW X1, which must be a first for a Range Rover product. "We wanted that sporty handling and chuckability, but also the ability to cross a sandy beach or grassy field, and we think we've got an excellent balance."
The easy option would have been to simply reskin Freelander underpinnings, especially as the two products share the same production line at Halewood. However, for numerous reasons, not least styling, this was never going to be an option, as Mitchell explains.
"At least 80% of the car is unique to Evoque, compared to Freelander; there are some small body-in-white panels that are common. The difference in the roofline between the two products drives the occupancy positioning, and the 'H' points of the passengers and driver are lower. That then drives the driveline's location, while the engine position also drives the pedal box and the steering column's relationship to the driver. If you change that, you change the instrument panel and pack, and then the cross car beam is different.
"In the bulkhead area, a few panels are similar, while the area along the tunnel is subtly different and everything rear of the back seats is new, because we have a unique fuel tank, due to packaging challenges. Although the two cars share some of the electrical harnessing, we have different suppliers between Evoque and Freelander.
"All of a sudden, you're changing a substantial amount of the vehicle to get the contours, in terms of overall package size and roof height."
Even when it comes to engines, there's commonality, although "the diesel is very similar between Freelander and Evoque but, clearly, there's a lot more refinement to get the Range Rover DNA we wanted and there's a new petrol engine that's a four-cylinder, rather than the six-cylinder in Freelander," he adds. Laughing, Mitchell says the only commonal point he can think of "is the road wheel nuts…"
Evoque first appeared at the 2008 Detroit Show as the LRX Cross-Coupe concept. Range Rover, perhaps stung by the criticism it received over the sensational-looking 2004 Range Stormer concept morphing into the much more conservatively styled Range Rover Sport, has adhered closely to LRX design. "It's difficult for people to tell the two apart," Mitchell states. "One thing that's obvious from LRX to Evoque are the door mirrors; we had some small, sexy ones, almost like an F1 mirror, but legislation, which is driven by the occupants' 'H' point, didn't allow me to use them."
Physically, the two cars are very closely aligned. "You wouldn't believe the amount of effort that went into making the car the right height, the design around the hood and the bottom of the 'A' post to comply with pedestrian impact," states Mitchell. "We kept trying different solutions to the packaging challenges and it was very difficult to get the roof height correct – especially on the three-door."
The body is a combination of steel, aluminium and thermo-formed plastics: following Range Rover tradition, the bonnet is made from aluminium, as is the roof, the latter laser welded and bonded to the steel body sides, using twin adhesive beads to ensure craftsmanship and rigidity. Body stiffness was a major challenge, especially in those models fitted with the optional one-piece Webasto full-size panoramic roof.
For the first time in a Range Rover, there's extensive use of thermo-formed panelling, from Plastic Omnium, for the front fenders and a one-piece tailgate that saves six kilograms over a conventional metal one. "Significant engineering went into getting rigidity into the top of the tailgate, because we have powered tailgates on some derivatives," explains Mitchell, adding: "There's a lot of webbing in there and we did a great deal of finite element analysis. It wasn't an easy task, because we've also moved the rear wiper assembly from where you would see it on the waistline and hidden it under the rear spoiler. We also put a lot of rigidity into the tailgate to mount the motor and mechanisms and the harness to it. Then we've got the power struts for opening and closing the tailgate."
An additional 30mm rear headroom in the five-door necessitated unique body sides, compared to the three-door with taller 'C' posts, although it still retains the same silhouette and floating roof graphic.
Other weight-saving techniques include boron high-strength steel in the 'A' posts and magnesium in the steering geometry to take weight out of the ball joints.
"There's a lot of aluminium in the suspension geometry components, but the frames themselves are high tensile steel. We looked at aluminium extrusions, but, by the time you've got the stiffness you want, there's no real weight saving." Mitchell's team also considered aluminium door skins, but concluded that the projected £20 million cost could be spent better elsewhere. "I'd rather spend it on something the customer can see and feel. We ended up doing the rear bumper beam in aluminium, as that saved 3.5kgs, versus doing the doors. Pound for pound, it was a better investment."
So far, all quite conventional, and, as an indication of the way Jaguar and Land Rover are merging their technologies, the Evoque gains the eight-inch TFT dual view screen that debuted in the Jaguar XJ, but with unique graphics. Meanwhile, the rising knob gear shifter on autos is a development of that first used on the XF and then developed for MY11 Range Rovers.
Where it does depart – to score a first in SUVs, as well as the first UK-European application at all – is offering the latest generation of BWI's MagneRide magneto rheological (MR) suspension as an option.
"One of the challenges for off-roading is to make sure we can get maximum bump and rebound," says Mitchell, " and sometimes, with passive dampers, you find that, at extremes, it goes into resistance and you can't get the full articulation. Of course, with MR, depending on how it is set, we don't get any suspension frictions that could restrict the amount of bump and rebound travel. Essentially, we get about an extra 4mm articulation with MR at bump and rebound."
The MR system is also linked in to Range Rover's Terrain Response, which includes a new dynamic response for the first time. Concerns about MR's durability in extreme temperatures that form part of the marque's stringent sign-off procedure were, says Mitchell, unfounded.
Using ZF's electric power-assisted steering has resulted in a 2% CO2 improvement and given Mitchell's team the opportunity to develop Park4You parallel parking ability that will squeeze an Evoque into a slot just 1.2 times the car's length. More importantly, peripheral sensors detect kerbs, allowing the Evoque to park within 100mm, while preventing expensive alloy wheels from being scuffed.
"Clearly, refinement was key," comments Mitchell, "and we spent a lot of time refining the aerodynamics to reduce wind noise," as well as eliminating pathways through the bulkhead, "We've redesigned the lower steering column seal at the bulkhead, not just because of the EPAS, but we stiffened the bulkhead in that area to get the right sealing. In terms of air paths, the 'A' and 'B' pillars either side of the front and rear door edges have been re-engineered to close gaps down and include more sealing."
The Evoque is a long way from Spen King's vision for Range Rover, but it's clear that it shares the same DNA. But there's more to Evoque than a new interpretation of that DNA; it also heralds a new direction in powertrain strategy.
Smaller, leaner, lighter engines
Evoque shares its diesel engine with the new XF (see page 6), albeit in a different state of tune, as Gary Reid, senior manager diesels explains.
"The peak 420Nm torque met the character we needed for Evoque; we didn't need the overboost with the calibration optimised for the performance and driveability you'd expect from a Jaguar.
"Range Rover is geared more towards low end torque, trailer towing capability and off-roading performance. So, whereas the curve on the Jaguar will get peak torque of 450Nm at 1750-2000rpm and then it tails off, in the Evoque peak torque is a lot flatter all the way through to 3000+rpm."
The Evoque's engine went through the same acoustic camera analysis that the Jaguar version did, with largely the same results. Common componentry, such as sound deadening socks around the injectors and sound deadening material around the starter motor, is shared. Differences include a bung in the lower pulley that was developed for, but not needed on, the XF, whereas the transverse location of the Evoque's engine brought the pulley closer to the driver and front seat passenger, so the bung was used to damp unwanted sound. Likewise, a sheath round the fuel pump is used on Evoque, but not on XF, due to packaging constraints.
One of the big challenges for any Range Rover engine is to meet the brand's unique off-roading requirements. "We didn't want to tool up for a new oil pan, "says Reid, "and we knew from Freelander the engine's capabilities, so it will tolerate fore and aft movement of ± 30° and ±27° lateral. From a DNA perspective, it would have been nice to get 45°, but the cost to achieve that would have been prohibitive and, anyway, people wouldn't take the car to those extremes."
The other major test is sealing the engine, but, as Land Rover-Range Rover had specified their sealing requirements with Ford and PSA at the start of the engine's development programme and, based on market experience since 2007, Reid and his colleagues were confident it would withstand off-road abuse.
However, says assembly set engineer Rob Carvell, the new two-litre GTDI petrol engine was a bigger challenge. Effectively, this is Range Rover's take on Ford's new EcoBoost engine that produces 176kW at 5500rpm and 340Nm from 1750rpm through to 4000rpm.
"The torque curve," Carvell comments, "suits Range Rover characteristics and the way the turbo selection went was to choose the minimum size necessary to achieve headline power figures that gave us the right characteristics for off-roading, which is, basically, low speed.
"The benefit of a small-sized Borg Warner KO3 turbo is time to torque characteristic, or lag, which is hugely reduced. "We were looking for 6-cylinder performance from a 2-litre turbo, with exceptional flexibility, thanks to its wide torque band.
Class leading
"The big message for GTDI is sustainability, with reduced friction and pumping losses, and state-of-the-art Direct Injection from Ford. But the way we have tailored its calibration and the emissions work in-house are class leading," claims Carvell.
Development of the engine started back in 2007 when Land Rover/Range Rover was still part of the Ford family. So, from the beginning, the off-roaders' prerequisites for oil, dirt and slurry ingress were engineered into the engine, as was its ability to withstand 45° angle of tilt fore and aft, as well as lateral, for five seconds. "Evoque was considered the worst-case scenario for this engine," says Carvell, "although meeting the 600mm deep water wading proved a challenge. We got round that by using a semi-sealed Denso starter motor."
Range Rovers are put through some brutal tests, including a ditch drop which puts excessive stress on engine mounts. To meet that, Carvell and his colleagues insisted on a four stud layout at the front of the engine, which has been carried over to the EcoBoost range. As with the diesel, special attention was paid to sealing, including a labyrinth seal for the front crankcase to survive the slurry test, as well as optimising belt drive for mud resistance and a plastic cover for the tensioner.
While twin balancer shafts smooth out the four cylinder engine, there were some NVH issues created by the DI systems injectors. "The injector itself has isolators that help to seal it against the cylinder head structure. There's also a 'rag and fluff' cover on the fuel rail that further reduces the tick. The pump body is exposed on an east-west engine, as it's driven off the exhaust cam, so it is sheathed in high density foam, reducing tick to an acceptable level for us. There's an acoustic engine cover as well."
Being an all-aluminium structure helps to keep weight down to 138Kgs shipped to Range Rover, but Carvell is particularly pleased with the plastic cam cover and intake manifold with honeycomb stiffening ribs, and fabricated exhaust manifold produced from pressed and welded sheet with hydroformed outer shells, and four internal runners going into a single collector that not only saves weight over a cast manifold, but also accelerates quick light off the catalyst.
Four decades on, and Range Rover is setting a new challenge to its rivals – Spen King would approve.
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Author
Ian Adcock
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