The paper reports the research activity related to the development of a High Exhaust Gas Recirculation (EGR) Spark-Ignition (SI), 8 valve engine equipped with a variable valve timing (VVT) device. The latter imposes an equal phase displacement on both intake and exhaust camshafts (dual dependent cam phaser).
Both experimental and theoretical analyses are carried out to characterize the performance of this engine architecture, and particularly to analyze the combustion process arising at low load and high EGR conditions. To this aim, a quasi-dimensional model for the simulation of the burning process is included as an external user-defined routine in a commercial 1D simulation code (GT-Power®).
The whole model is validated at both wide open throttle (WOT) conditions and part-load, and then it is mainly utilized to find, by means of a parametric analysis, the lowest fuel consumption at low load. Proper values of camshaft phasing, spark advance, butterfly-valve opening and EGR ratio are so defined in these operating conditions.
In addition, the user modified 1D code is also linked to an external optimizer (ModeFrontier®) to verify if additional improvements can be gained when a different phasing is specified for intake and exhaust camshaft (dual independent cam phasers).