Abstract
Keywords - downsizing, diesel engines, CO2 reduction, power density, emissions
Regulated emissions, CO2 values, comfort, good drivability, high reliability and cost effec-tiveness: this is the main frame for all future powertrain developments. Diesel powertrains for passenger cars and also for commercial vehicle applications face some challenges in order to comply with the future European and current US emission legislation while keeping fuel-efficiency, good drivability, and an acceptable cost level.
One widely discussed approach for fuel consumption improvement within passenger car applications, in addition to the implementation of further engine and vehicle measures, is to incorporate the downsizing effect; some publications have already discussed strategies for Diesel engines with reduced displacement and the correlating impact on fuel consumption, emissions, and the necessary hardware re-configuration. Still under discussion is the question as to what extend downsizing passenger car Diesel engines is possible and what the margin are for further performance improvements with downsizing.
In this context, this publication deals with the further potential of increasing the specific power for HSDI Diesel engines. In detail, this includes the topics of measures necessary to achieve a higher specific power output while keeping the engine-out emissions favorable for legal demands and fuel economy on a superior level. In addition to that, by means of cycle simulations, the achievable degree of downsizing, dependent on the specific power, is ana-lyzed and consequences for engine-out emissions and fuel consumption are formulated. The shown results are based on theoretical pre-studies, representative single cylinder measure-ments, as well as test cycle simulations.