State-of-the-Art V8 for Volvo XC90
An entirely new powertrain featuring a V8 engine, six-speed automatic transmission and the latest-generation AWD system will make its debut at Paris motor show on 23 September. This leading-edge V8 engine marks a new turning-point in Volvo Cars’ history. It is the first V8 the company has produced since it was founded in 1927, and the Volvo XC90 is the first model to be powered by the new engine.
One requirement for the new V8 engine was that it had to be installed transversely in the engine compartment, just like all other Volvo engines.
“A transverse engine is helpful in maintaining the frontal crumple zones in the XC90 and thus not compromise on protective safety,” says Volvo’s Hans Wikman. For this reason, extremely compact external dimensions were essential for the new engine. This also explains the choice of just 60 degrees between the two banks of cylinders – as opposed to the more conventional 90 degrees.
The imbalance that is a natural consequence of a 60-degree ‘V’ configuration between the banks of cylinders is prevented by a counter-rotating balancer shaft.
To maintain overall compactness, all the ancillary units such as the alternator are fitted directly onto the engine itself without any space-stealing brackets. The starter motor is fitted above the transmission for the same reason.
What is more, the exhaust camshafts are driven by secondary chains running off the inlet camshafts, saving additional space.
The left-hand cylinder bank is offset half a cylinder ahead of the right bank, contradicting normal practice in the automotive world – so the engine can slot neatly into the structural beam network of the XC90 and thus enhance collision safety.
“We’ve tailored this V8 specifically for the XC90,” confirms Wikman. The result is a V8 that is just 754mm long and 635mm wide – the most compact V8 on the market compared to engines of equivalent capacity.
As a result of these compact dimensions and the fact that both the block and cylinder head are cast in aluminium, Volvo’s new V8 weighs just 190 kilograms.
The new engine from Volvo is the cleanest petrol V8 on the market today. It meets the American ULEV II (Ultra Low Emission Vehicle, stage II) requirements and the forthcoming Euro 5 requirements for Europe – which no other petrol V8 has yet managed.
The four-valve engine also features continuous variable inlet and exhaust valve timing (CVVT). This system adjusts the valve opening phasing so they suit the engine’s revs and load conditions. The engine is thus utilised more efficiently, cutting fuel consumption, lowering emissions and increasing performance.
The Volvo XC90 V8 produces 232kW and its torque – the most important characteristic of a V8 engine – is a massive 440Nm at 3900rpm. And at the sort of revs at which most driving takes place, around 2000rpm, no less than 370Nm awaiting the driver’s call.
“We chose to give our new V8 a sporty yet sophisticated appeal, with masses of power in reserve even as the revs rise,” explains Svensson.
Acceleration from standstill to 100km/h takes 7.0 seconds and fuel consumption is 13.0 litres/100km (preliminary figures). Top speed is limited to 210 km/h.
The engine note is an important detail, and this is something to which Volvo Cars paid careful attention during the development of the new engine. In the hunt for that characteristic V8 rumble, it is the position of the inlet manifolds that is the main deciding factor.
“Our new V8 has just the right sort of charismatic off-beat V8 burble, but it is somewhat more muted in the European fashion rather than producing the more traditional meaty American throb. We feel this provides better audio comfort for the car’s occupants,” comments Svensson.
The power from Volvo’s 4.4-litre V8 engine passes through an entirely new six-speed automatic transmission. This compact transmission was designed specifically to handle the high torque loads produced by the V8 without interfering with the XC90's overall structure. Sixth gear is a pure overdrive ratio to ensure quiet cruising and low fuel consumption.
“We get simply massive ‘take-off’ force with this auto transmission,” says Svensson. “And at the same time, it has a very sporty nature and does not change up in the middle of a curve, for instance, but instead stays in the same gear until the bend straightens out.”
The new six-speed transmission is of Geartronic type, which means that it can also be shifted manually. There is also a possibility for Lock-up, and slipping Lock-up, on all gears.
To ensure the optimum balance between driving properties, performance and fuel consumption the engine and transmission are treated as one unit. This is achieved with new software developed by Volvo, called CVC (Complete Vehicle Control). CVC is part of the integrated software package used, both in the engine control module and the transmission control module.
Among the many benefits of this approach was the possibility of integrating an overdrive sixth gear while still maintaining good driving performance by adjusting functionality, gear and torque to suit current conditions.
The third ingredient in the new Volvo Cars V8 powertrain is the electronic AWD four-wheel drive system, which now features Instant Traction. This new technology – which Volvo Cars is the first automaker in the world to introduce – improves the scope for quick getaways and provides enhanced traction on slippery surfaces. It has been developed by the Swedish company Haldex.
“A non-return valve allows us to use software to control the base torque that is programmed into the AWD system. When starting off from standstill, 80Nm of torque is pre-charged in the system since the non-return valve prevents the unit from becoming totally drained of hydraulic fluid.
“This reduces the usual wheelspin of about one-seventh of a turn that the current system permits before the power is delivered to the rear wheels,” explains Svensson.
The AWD system has also been upgraded to handle the power of the V8 engine. Maximum short-term torque at the rear wheels has been increased by 50 percent compared to current XC90.