Kirchheimbolanden, July 28, 2005 – Commercial vehicle engines are the "marathon runners" among internal combustion engines. They need to develop tremendous torque to allow the vehicle to pull away on a hill, while at the same time having to provide sufficient power even at low engine speeds in order to maximise fuel economy when driving on highways or motorways. Power output, fuel consumption and emission control in particular will make extreme demands on the turbocharger technology of the future, as the stricter Euro 4 emission standard also comes into force for commercial vehicles from 2006.

Now that the exhaust turbocharger with variable turbine geometry (VTG) has become the state of the art in diesel engines for passenger cars and to some extent for commercial vehicle applications, the limits of single-stage turbocharging have almost been reached. A further increase in the rated power usually leads to a reduced starting torque.The developers of new turbocharging systems are therefore faced with the following challenge: achieving a further rise in the rated power of an engine would require the use of a relatively large turbocharger. However, in order to ensure that a high boost pressure is generated even at low engine speeds, the turbine and compressor would have to be made much smaller. The ideal solution would therefore be a combination of both. With its R2SÔ, BorgWarner Turbo Systems has developed a regulated 2-stage turbocharging system that provides exactly such an ideal solution. This technology, which following its successful debut in the BMW 535d is now also conquering the commercial vehicle market, allows an infinitely variable adaptation of the turbine and compressor side to any engine operating point.

High Power Output with Reduced Emissions

In regulated 2-stage turbocharging, two differently sized turbochargers are arranged in series: a large low-pressure turbocharger and a small high-pressure turbocharger. Unlike the system used in passenger car applications, regulated 2-stage turbocharging for commercial vehicles has only one bypass valve as an actuator on the high-pressure turbocharger. In this arrangement, the turbochargers are tuned in such a way that both of them are active at all engine operating points. The boost pressure is controlled by the external bypass. This allows continuous control without any drop in boost pressure, as occurs, for example, in register turbochargers.

"Regulated 2-stage turbocharging can now provide commercial vehicles with a technologythat meets the highest power requirements and complies with future emissions standards," said Hans-Peter Schmalzl, Vice President Technology at BorgWarner Turbo Systems. These are the main benefits at a glance:

· Pronounced and high torque characteristic
· Increase in rated output
· Reduction in rated speed
· Improvement in boost pressure characteristic
· Potential for reducing NOx emissions
· Improvement in non-steady-state behaviour (acceleration behaviour of the engine at full throttle)
· Use of proven and series-ready components with a long lifetime and high reliability

BorgWarner Turbo Systems already has orders from leading manufacturers to supply regulated 2-stage turbocharging systems for commercial vehicles.

BorgWarner Turbo Systems, a division of the globally active automotive supplier BorgWarner Inc., is the world’s market leader for turbocharging systems for passenger cars and commercial vehicles as well as industrial, locomotive and marine engines. BorgWarner Turbo Systems has a workforce of more than 3,658 employees at twelve locations in eleven countries. The headquarters of the company are located in Kirchheimbolanden, Germany.

Auburn Hills, Michigan-based BorgWarner Inc. (NYSE: BWA) is a product leader in highly engineered components and systems for vehicle powertrain applications worldwide.The company operates manufacturing and technical facilities in 62 locations in 17 countries.Customers include Ford, DaimlerChrysler, General Motors, VW/Audi, Toyota, Hyundai/Kia, Renault/Nissan, Honda, Caterpillar, Navistar International, Peugeot and BMW. The Internet address for BorgWarner is: http://www.bwauto.com.