Secrets of the XC90
The Volvo XC90 is claimed to be a vehicle designed for all types of roads. Even though it is not basically intended for off-road driving, the combination of electronically controlled 4WD and 218 mm of ground clearance creates the right preconditions for continued progress when the going gets rough.
The feeling of safety that the high seating position gives the driver is supplemented with the knowledge that he or she can control the car with the help of instant, well-weighted response from the chassis, engine and brakes. Progress is thus more relaxed and comfortable.
The chassis in the XC90 is designed to give the vehicle the same ride and roadholding as a passenger car. It is based on the chassis of the S80, S60 and V70; for the XC90, however, the suspension has been beefed up and dimensioned to handle heavier loads and higher ground clearance.
The rear suspension is of the multi-link type and is completely insulated, with the dampers and springs attached directly to the subframe. This results in a quieter ride, since road and transmission noise is largely filtered out before it reaches the bodywork. The front suspension has MacPherson struts and, together with the new ZF steering gear, increased precision and sharp response are promised.
The XC90 has an extremely wide track (1634 mm in front, 1624 mm behind) and a long wheelbase (2859 mm). This makes for exceptional stability, with the vehicle behaving very consistently and dependably even on curving, twisting and uneven roads. XC90 wheel options go right up to 18 inch diameters.
The brake system has a size and specification which will provide adequate stopping power even when the XC90 is fully loaded with seven people and their luggage. This is achieved with an optimised brake system and EBA (Emergency Brake Assistance). This system monitors how quickly the brake pedal is pressed, and can thus determine if the driver is panic-braking. In such a situation, the brake pressure is boosted to maximum in the shortest possible time, thus reducing the stopping distance.
Electronically-controlled AWD
One important ingredient in the recipe for safe driving pleasure in the XC90 is its electronic AWD (All-Wheel Drive) system, developed in close cooperation with one of the foremost experts in this area – Haldex of Sweden. Just like in previous AWD models from Volvo, the 4WD system in the XC90 operates entirely independently of driver input, meaning that power is distributed automatically between the front and rear wheels for best possible grip on all types of road surfaces.
The electronically-controlled AWD system is intelligent. It monitors the vehicle’s contact with the underlying road surface and assesses the signals that the driver receives through the steering wheel, brake pedal and accelerator. This information then helps determine whether, and if so how, the system should respond.
In normal driving on dry roads, almost all power is delivered to the front wheels. If the road surface causes the front wheels to slip, power is proportionately diverted to the rear wheels. With electronic-activation, AWD engagement takes place extremely quickly – after just 1/7th of a wheel turn, which eliminates wheelspin and ensures reliable road grip.
As a result, the AWD system in the Volvo XC90 has all the benefits of permanent four-wheel drive, without the accompanying disadvantages such as higher fuel consumption and heavier weight.
The electronic AWD system interacts in the Volvo XC90 with the active chassis systems DSTC – Dynamic Stability and Traction Control. This is an anti-skid system that automatically counteracts any initial tendency towards a skid before the driver even has time to notice. The system continuously compares the vehicle’s direction of progress with the driver’s steering wheel movements. If the vehicle shows any tendency to start skidding, the brakes are instantly applied to one or more wheels as necessary until the vehicle stabilises and the skid is avoided. DSTC also includes an anti-spin system that automatically brakes the wheel that spins, so that drive is diverted to the wheel with the best grip. It also controls the engine torque.
Engine choices
The XC90 engine options number three at this time, all having aluminium cylinder heads and blocks. An in-line 6-cylinder petrol engine with a displacement of 2.9 litres, equipped with twin turbochargers. It produces 200 kW (272 bhp) and has no less than 380 Nm of torque from just 1800 rpm.
Next is an in-line 5-cylinder 2.5-litre petrol engine with a light-pressure turbocharger. This has a power output of 154 kW (210 bhp) and maximum torque of 320 Nm from 1500 rpm.
An in-line 5-cylinder 2.4-litre common rail turbodiesel engine with 120 kW (163 bhp) and 340 Nm from 1750 rpm is also available for those who prefer oil-burners.
All three engines come from Volvo’s passenger car range, but they have been re-tuned to suit XC90. In particular, the petrol engines produce far more torque from lower down the rev range.
The 6-cylinder engine is the same unit that powers Volvo’s largest sedan, the S80 T6. It has a parallel turbo system – two small and highly efficient turbochargers that are installed alongside each other. They are driven by and feed three cylinders each.
In the XC90 application, the T6 engine’s displacement has been enlarged from 2.8 to 2.9 litres and it is equipped with variable valve timing (CVVT) on both the inlet and exhaust sides. CVVT adjusts valve timing to suit the engine’s current revs and load, and it thus exploits the engine more effectively, reducing fuel consumption and emissions. More significant, however, is that maximum torque is available from just 1800 rpm, compared with the 2000 rpm of the 2.8-litre version.
Best of two worlds: Geartronic
The XC90 T6 is fitted with a 4-speed Geartronic automatic transmission as standard. With Geartronic, the driver gets the best of both worlds: on the one hand, the transmission can be left to take care of gearchanging entirely automatically, or the driver can over-ride the system to change gears manually without a clutch pedal.
The automatic transmission is adaptive, which means that it monitors the driver’s driving style and adjusts the gearchanging pattern accordingly. It also features a “W” setting for winter driving on slippery surfaces. In this mode, the car starts off in a higher gear to avoid wheelspin and loss of control.
Top level safety
Customers expect Volvo to retain its lead in the field of safety irrespective of vehicle type. With the launch of its first-ever SUV, Volvo enters an entirely new segment with the aim of also leading the way in terms of safety.
With the entry of Volvo into the SUV market, there is increased focus on several new areas. One of them is roll-over accidents, where the vehicle rolls over onto its roof one or more times.
In order to help reduce the risk of a roll-over situation, the XC90 is equipped with an active stability-enhancing system known as Roll Stability Control or RSC. The system uses a gyro-sensor to register the vehicle’s roll speed and roll angle. Using this information, the terminal angle is instantly calculated and thus also the roll-over risk. If the calculated angle is so great that there is an obvious risk of rolling over, the DSTC (Dynamic Stability and Traction Control) anti-skid system is activated. This helps reduce the risk of a roll-over accident initiated by extreme manoeuvers. RSC is the only active stability-enhancement system on the market to measure the car’s roll angle. It was developed jointly by Volvo and Ford.
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