BorgWarner of Auburn Hills, MI has produced a regulated
two-stage and variable turbine geometry (VTG) turbocharging technology for BMW's
3.0-liter straight six-cylinder diesel engine. The turbocharging technology was
designed to boost performance while improving fuel economy by 4 percent.
BorgWarner worked with BMW to unite two advanced
technologies in an effort to accelerate the carmaker's engine downsizing
strategy without compromising power and torque. The turbocharging system consists
of two series-connected turbochargers. A smaller turbocharger engages at low
engine speeds. As the engine reaches mid-range speeds, a larger, low-pressure
turbocharger takes over, providing the boost pressure to reach maximum engine
torque. The combination was designed to achieve both high torque at very low
revs and maximum output at high engine speeds.