Volvo XC70 D5: Scandinavian Diesel
Until recently, Volvo didn't have a decent turbo diesel that could be installed on the latest SUVs like the XC90 or XC70. But the company had enough engineers who were able to convince the management not to buy the diesel from the neighbors of the Premier Automotive Group, but to find application for their own forces and developments.
Not having a diesel engine of your own in the range of engines is now considered a crime against the consumer with a deliberate punishment in the form of low sales volumes. Over the past decade, the German carmaker's solar-powered fashion has brought up a whole generation of drivers in Europe for whom the economy and eco-friendliness are at the top of the list of priorities. And while these enthusiasts have not seized the sole leadership throughout the Old World, the non-Aryan brands are looking for valuable personnel - specialists in diesel engines.
Until recently, Volvo didn't have a decent turbo diesel that could be installed on the latest SUVs like the XC90 or XC70. But the company had enough engineers who managed to convince the management not to buy the diesel from the neighbors of Premier Automotive Group, but to find application for their own forces and developments. For example, to use a five-cylinder aluminum cylinder block from model 850 from far 1991, which was already developed for diesel parameters. As the cylinder head of the new D5 engine block is also made of aluminum, the engine without an attached gearbox weighs only 163 kilograms - a significant contribution to the achievement of decent performance and economy. In addition, the in-line five-cylinder engine is still very compact, leaving enough space under the hood for deformable safety zones in the event of an accident.
When the work on the engine was completed, it turned out that in many respects it is in no way inferior to the five-cylinder gasoline T5. Developing 163 hp and allowing to reach a speed of 195 km/h, it produces 340 Nm of torque at 1750 rpm, while the 250 hp T5 makes 330 Nm at 2500 rpm. And even more so for the gasoline engine and did not dream of such figures for the economy (8.4 liters per 100 km/h), allowing the all-terrain vehicle XC70 D5 to drive with a full tank of at least 810 kilometers. This excellent result was achieved due to intensive work to reduce internal friction, which included maximum simplification of the internal architecture of the engine, weight reduction of parts, especially pistons and connecting rods, reduction of vibration, which usually have a negative impact on engine performance.
The VNT (Variable Nozzle Turbine) turbine contributes to the excellent torque data, whose blade guides, which change their configuration at the command of the engine control unit, allow optimizing the amount of air entering the turbine as the engine runs. This solution allows us to achieve high boost pressure even at low speeds and make the torque curve more convenient. Like all modern diesel engines, this turbo motor is equipped with a common-rail system. However, the XC70 D5 is debuted with the second-generation system, which is not only able to supply fuel under higher pressure than before, but also to react adequately to the greater load of the car. As before, the amount of fuel and injection time is controlled by electronics and high-speed solenoids, but the diesel fuel now enters the cylinders at higher pressures, up to 1600 bar.
Equipped with an automatic five-band adaptive transmission, the motor allows the sprinter to travel from 0 to 100 km in 11.5 seconds. The manual transmission will be installed on the vehicle from the second half of 2003.
According to the company's plans, the new engine was prepared specifically for the all-wheel-drive system, which is equipped with the XC70 D5. It includes an electronically controlled friction clutch from the Swedish company Haldex, which gives the chassis an instantaneous reaction to slippage or skidding - only 1/7 of the wheel rotation is enough for the system to redistribute the torque to other wheels.
The Haldex friction package is reminiscent of a multi-disc clutch in an oil bath that distributes torque between two axles. At the slightest mismatch of speeds of rotation of shafts in a transmission, the piston pump begins to work, instantly increasing the pressure of oil in the system, thanks to which the friction closes and balances the speed. The oil is then returned to the tank using a special valve with an electronic oil pressure controller.