The adoption of downsizing and turbocharging in modern spark ignition engines results in a considerable increase of the thermal loads acting on the components facing the combustion chamber, therefore causing higher thermo-mechanical stresses and abnormal combustion probability, with negative consequences on engine reliability. CAE tools (CFD/FEA) can be used in early design phase to estimate the thermal loads and the thermal field of engine components, with significant reduction of time-to-market compared to conventional product development based on try and error procedures. The aim of this thesis work, conducted at POWERTECH Engineering S.r.l. in collaboration with McLaren Automotive, is the development of a 3D-CFD Conjugate Heat Transfer (CHT) methodology for the characterization of high-performance multi-cylinder spark ignition engine thermal field, with particular emphasis on the piston thermal field.