The integration of CPT’s variable torque enhancement system (VTES) supercharger technology virtually eliminates all perceptible turbo-lag even in the absence of variable geometry turbine technology normally fitted to turbocharged diesel engines. (Earlier post.)

VTES is an air-cooled Switched Reluctance machine, coupled to electronics and an optimized radial compressor, that delivers high airflow, pressure and efficiency. The product is designed for integration into both Otto and Diesel engines to deliver enhanced torque, emissions control and CO₂ reduction.

A system of cooled, external exhaust gas recirculation (EGR), Lambda = 1 operation at all engine loads up to 4,000 rpm and advanced thermal management further enhance the CO₂ reduction potential of the powertrain.

The philosophy of ‘down-speeding’ is fully employed through the fitment of gear ratios more normally associated with turbocharged diesel engines. Successful down-speeding relies heavily on the immediate availability of high torque levels at very low engine speeds in response to driver inputs.

Through careful integration of the above technologies and the implementation of engine stop-start and smart alternator control, AVL is able to demonstrate CO₂ emissions of 159 g/km for a VW Passat demonstration vehicle at 1,590 kg vehicle mass, which also meets Euro 5 emission standards. By way of comparison, a series production Passat emits 165g/km when fitted with a 2.0l TDI (170PS) diesel engine and 194 g/km when fitted with a 2.0l TFSI (200PS) gasoline engine.

At the same time the 200PS engine delivers high levels of performance & refinement while VTES ensures strong transient response even at the lowest engine speeds, equivalent to a naturally aspirated engine of twice the capacity.

Getting a gasoline engine to deliver the lower CO₂ emissions of a diesel engine is something of a holy grail for the motor industry. The challenge is to retain the driveability at low engine speeds in order that drivers can fully realise the benefits of down-speeding. An electric supercharger can react instantly to these transient load conditions, delivering up to 25kW of additional power at the crankshaft in less than a second.

—Nick Pascoe, CEO CPT

The AVL demonstrator will be available for test drives at the International Vienna Motor Symposium, 7-8 May 2009, where the technological achievements of the vehicle will be included in an opening presentation entitled ‘Future Powertrain Systems in a Fast Evolving Global Environment’ to be delivered by Prof. Dr h.c.H.List, chairman and CEO of AVL.