With innovative engineering solutions such as sequential twin turbochargers, ceramic glow-plugs and piezoelectric fuel injectors, Volvo's engineers have succeeded in cutting fuel consumption to 45.6mpg, while CO2 emissions are 164g/km. The D5 develops 205hp and 420Nm of torque.
Volvo's new D5 engine has a displacement of 2.4 litres, offering power and response as soon as the accelerator is depressed. The performance and driveability enhancements have been made with the use of twin different-sized turbochargers that operate in sequence to provide added power within a broader rev range. The result is an immediate response and rapid acceleration at all speeds, with smooth power delivery between the two turbo ranges. At lower rev ranges, the smaller turbocharger ensures rapid acceleration without any perceptible lag, while at higher ranges, the larger turbocharger delivers the high levels of power torque not available with a single unit. This power means there are always ample resources for quick overtaking, particularly between 50 and 75 mph.
This twin-turbo technology has also made it possible to introduce higher levels of exhaust gas recirculation (EGR) across a wider rev range than before. This harnesses the two turbochargers' different properties optimally to deliver high performance and low fuel consumption.
Advanced injection technology using piezoelectric fuel injectors provides precise distribution of the atomised fuel in the combustion chamber, resulting in efficient combustion and low emissions. At the same time, this technology and the efficient combustion deliver a refined engine note, bearing a closer resemblance to the noise of a six-cylinder petrol engine. The engine offers excellent results in terms of noise comfort and noise perception, technically known as NVH or Noise, Vibration and Harshness.
The injection system with its piezoelectric fuel injectors and high-efficiency fuel pump also help cut fuel consumption through extremely rapid and precise injection sequences and high injection pressure, resulting in particularly effective combustion.
In addition to twin turbochargers, piezoelectric fuel injectors and improved EGR control, the new D5 engine has been equipped with ceramic glow-plugs, an innovative solution that delivers excellent cold-starting properties thanks to a very quick warm up period. They reach a temperature of 1000 degrees Celsius in just two seconds, making the engine easy to start and thus cutting emissions. In certain driving conditions, such as at very low revs, the heat generated by the ceramic glow-plugs can also be used to increase the temperature in the cylinders, further improving combustion efficiency.
The advanced injection technology makes it possible to supply additional fuel in tiny increments after the main injection charge, a process known as post-injection, with the aim of removing any soot particulates in the exhaust gases.
The engine was developed on a modular basis in terms of both design and building method, using standardised mountings for the turbochargers and other components. This makes it easier to install in other Volvo models and gives more scope for further development to meet future demands.Facelift for Volvo S80
26 February 2009