Our Direction for ICE (Internal Combustion Engine) – Consideration of Engine Displacement

Authors

M. Hitomi, Fellow of the Japan Society of Mechanical Engineers, Mazda Motor Corporation, Hiroshima, Japan

Year

2015

Print Info

Fortschritt-Berichte VDI, Reihe 12, Nr. 783

Summary

Based on the availability of high octane gasoline fuel as standard fuel in Europe the worldwide trend of turbocharging and reduction of engine displacement is deduced to increase engine efficiency (downsizing).The primary factor of fuel consumption reduction through downsizing is the reduction of engine mechanical friction losses and pumping losses. At the time, the compression ratio must be reduced. To compare the reduction of compression ratio against downsizing rate while keeping same engine power by turbocharging and same knock resistance by compression ratio reduction finally the trade-off among engine mechanical friction, pumping losses and compression ratio requirement need to be considered versus the efficiencies at each engine load. The result is as follows: In the low load range, downsizing engines with turbocharging have advantages in comparison to large displacement and naturally aspirated engines with high compression ratio. In the medium and high load range, large displacement and naturally aspirated engines with high compression ratio have advantages.