Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
The Downsizing of internal combustion engines (ICE) is al- ready recognized as a very suitable method for the concurrent enhancement of the indicated fuel conversion efficiency (IFCE) and the break mean effective pressure (BMEP) while also decreasing the CO2 and NOx emissions , . The Ultra-Downsizing concept was introduced in  as a still higher development stage of ICE and implemented by means of real Atkinson cycles, using asymmetrical crank mechanisms, combined with a very intensive multistage high- pressure turbocharging with intensive intercooling. This allows an increase of ICE performance while keeping the thermal and mechanical strain strength of engine components within the current usual limits. The investigations from  were carried out using the simu- lation tool BOOST (AVL Co). The three-stage turbocharging with intensive intercooling used in this process and the release of heat during combustion are controlled by numerous parame- ters. As a consequence, it is very difficult to harmonize them in order to optimize concurrently IFCE, BMEP and emissions. For this reason, the ideal V,p,T-model presented in  has been revised, improved and adapted to better meet the BOOST simu- lations. With help of this new, ideal V,p,T-model, it is possible to evaluate adequately the potential for improving the perfor- mance of Ultra-Downsizing.