The Influence of Cylinder Cut-out on High Performance Engines Fuel Efficiency

Cylinder cut-out is a very promising strategy to reduce fuel consumption at partial load on high performance, big capacity S.I. engines. The simplest way to deactivate a set of cylinders is to design an air metering system featuring a separate control on the gas flow delivered by the firing cylinders and the deactivated ones. Particularly, the throttle valve controlling the motored cylinders should be kept wide open, in order to reduce pumping losses, while the opening angle of the other throttle should be electronically modulated in order to meet the load target. In this way, total pumping losses are strongly reduced, thus fuel efficiency is enhanced. The benefit of the strategy described above, along with a traditional VVA control, is evaluated with reference to two high performance naturally aspirated engines, produced by Ferrari and Maserati. The study is carried out by means of 1D cycle simulations, integrated by experimental data. It was found that the increase of fuel efficiency in the European Driving Cycle is consistent (12-19%), while the fully electronic power train management should minimize drawbacks.