• Improved performance and lower emissions
• Larger, electronically controlled turbocharger
• Improved fuel-injection system
• More powerful engine management system
• More efficient EGR system
• Maintenance-free particulate filter
• Six-speed automatic gearbox
• All Wheel Drive with Instant Traction for XC90
• Class leading fuel efficiency - 9L/100km

The Volvo Car Corporation in 2005 unveiled a new generation of its own five-cylinder diesel engine. The five-cylinder engine has been extensively improved and refined and debuts in Australia in the XC90 D5.

The result is an improved engine with a new driving character offering considerably higher performance and improved drivability. At the same time, there is a sharp reduction in tailpipe emissions.

This new diesel engine is offered in Europe at three power outputs. However, Australia will see only the most potent variant - the 136kW, 400Nm D5.

Via several technical improvements, the D5 engine produces an additional 16kW to achieve a maximum output of 136kW. The increase provides excellent high-speed performance with responsive acceleration and efficient pulling power.

Torque improves dramatically from 340Nm to 400Nm, and the D5 engine is easily capable to pushing the large XC90 with impressive urgency. Low rev engine response is considerably improved and the D5 engine revs willingly to 5000rpm.

"We have improved nearly everything in the engine," says Jörgen Svensson, Chief Program Engineer. "The driver will perceive it as a lively petrol engine, only more powerful and more environmentally efficient."

New-generation turbocharger
The new-generation turbocharger is electronically controlled to achieve precise control of charge pressure. A larger compressor wheel provides higher torque and output. Furthermore, the variable vanes have been cambered for a more efficient flow of gas at all compressor speeds, resulting in an increased level of turbo efficiency. The improvements contribute to faster acceleration and better high-speed performance.

The turbocharger's centre bearing housing is now water-cooled, which is unusual in diesel engines. Water cooling is necessary because of the higher performance of the new engine and provides continued cooling of the turbocharger after the engine has been switched off. This is particularly beneficial during short stops after high-speed driving.

Refined injection technology
The use of a new electronically controlled multi-throttle system in the inlet ports allows for infinitely variable regulation of the swirl level, and combustion can be adjusted extremely accurately according to the driving situation and the current engine speed and load.

"We have also made the combustion chambers larger, thereby lowering compression," says Svensson. "By doing so, we have gained two things: higher performance and lower emissions."

The injection system now uses new injectors with seven finer nozzle openings as opposed to five in the previous engine. This results in a more finely atomized fuel mixture and more efficient combustion. Injection takes place in three steps: pre-injection, primary injection, and post-injection. The injection phase is new and contributes to cleaner combustion and also to regeneration of the particulate filter.

A completely new, electronically regulated quick glow system results in considerably reduced glow times, also making it easier to start the engine in cold weather.

New management system contributes to reduced emissions
The new diesel engine has very low emissions, thanks to a number of new and refined functions. For example, emissions of nitrogen oxides (NOx) have been halved.

A new-generation engine management system, with increased capacity and a greater number of sensors, offers more accurate control of the engine's functions. This includes electronic control of the throttle and the new, more powerful EGR (Exhaust Gas Recirculation) valve for more precise regulation of the air supply and recirculation of exhaust gases.

"We also have a completely new EGR cooler," says Svensson. "This lowers the combustion temperature very efficiently, thereby reducing emissions."

The catalytic converter is now fitted nearer to the engine to promote faster warming and thus faster startup of the exhaust cleaning process. The catalytic converter is also larger than before. In addition it has been supplemented with an oxygen sensor that precisely regulates the fuel mixture and emissions.

Particulate filter is standard
Volvo's new diesel engine has a particulate filter as standard equipment. It very effectively removes soot particulates from the exhaust gases, with filtration efficiency above 95 percent. The filter is a CDPF - Coated Diesel Particulate Filter - in which a special coating helps burn the particulates. Therefore, no additives are needed, and the filter requires no maintenance. Burning away soot particulates takes approximately 20 minutes and occurs automatically at 500km to 1000km intervals, depending on driving conditions.

Six-speed automatic gearbox
A standard pairing, the D5 engine combines with a six-speed automatic to accommodate the engine's high torque loads. The six speeds contribute to sportier driving and improved NVH.

The new six-speed automatic transmission contributes to the model-year XC90's agility and refinement. The engine's broad torque curve works in harmony with the quick shifting automatic to achieve quite impressive throttle response at nearly all engine and vehicle speeds. In particular, the gearbox is able to kick down without delay.

The torque converter features a lock-up that is allowed to slip over a wide range of engine speeds for effective pulling power and good drivability, particularly when transporting heavy loads or towing a caravan.

All Wheel Drive with Instant Traction
The improved AWD system with Instant Traction, which was introduced on the Volvo XC90 V8, is now combined with the D5 diesel engine. Instant Traction makes starting easier on slippery surfaces by immediately distributing the right amount of power to the rear wheels the instant the car starts to move.

"The D5 engine with a six-speed gearbox and All Wheel Drive is a nearly unbeatable combination," says Svensson. "It offers enormous driving pleasure while also providing power and low-rpm capacity for the most demanding uses."

Summary
Most of the measures taken on Volvo's new diesel engine result in an increase in performance and reduced emissions. The primary purposes are explained in the following summary:

For increased performance

• The injection system has been improved with new injectors and a more advanced injection process
• A new-generation turbocharger, with larger compressor wheel, cambered vanes and electronic control
• The gas exchange system has been upgraded for optimum flow of air and exhaust gases, with low pressure losses

For lower emissions

• A new-generation engine management system with a greater number of sensors for more precise regulation
• The EGR (Exhaust Gas Recirculation) system is new, with faster regulation of the flow
• The EGR cooling is new with higher capacity
• The air throttle is new and electronically controlled in order to more effectively control EGR flow, reduce noise and regulate the temperature
• Air swirl in the combustion chamber is infinitely variable for more efficient combustion
• The lowered compression ratio (from 18:1 to 17:1) with new and larger combustion chambers lowers compression temperatures and reduces emissions
• The quick glow system is new and electronically controlled for faster cold starts
• The catalytic converter is larger and fitted with an oxygen sensor for precise emission control
• The Coated Diesel Particulate Filter (CDPF) is standard on all versions