Vehicle Refinement Challenges for a Large Displacement Engine with Cylinder Deactivation Capability

Ever increasing challenges on reducing emissions and improving fuel economy has led to the development of not only alternate fuels but also new Powertrain technologies. One such technology employed within the new Bentley Mulsanne is cylinder deactivation, where 4 out of 8 cylinders of a large displacement V8 engine are turned off during light load conditions.

This paper identifies the considerations and technical development that was undertaken to deliver limousine levels of cabin refinement with imperceptible half engine mode operation under cruise conditions whilst achieving the desirable sporty character of a large V8. A practical approach to transfer path analysis incorporating structural path disconnections and exhaust orifice routing and its benefits are discussed. The selection of a dual mode exhaust, employment of specific half engine mode torque converter slip strategy and the development of a power unit mounting system for both isolation refinement and power unit control are presented.