Enhancement of i.c. engine performances in terms of fuel economy and environment and human health preservation is an increasing key factor of the research in recent times. Mainly, that is due to the more and more stringent European and worldwide regulations tending to limit pollutant emissions to carbon monoxide, unburned hydrocarbons, nitrogen oxide, and particulate matter. Development of direct injection strategy (DI) in spark ignition (SI) engines partially fulfilled these tasks, as they run at higher compression ratios, with respect to port fuel injection (PFI), and operating with different injection strategies, so a greatest control over the air-to-fuel ratio is achieved. However, today the engines’ complexity and the number of sub-systems have increased, so the traditional techniques used for their optimization are often inadequate for the required challenges of high power output and low environmental impact. In this change of perspective, deeper experimental approaches such as numerical simulation tools, as CFD models, are becoming increasingly important to accelerate the time to market of high-efficiency clean power units for transportation. The heat transfer during the injection and the combustion phases plays a fundamental role in engine development as heat losses influence the combustion efficiency, the exhaust emissions, and the thermal stresses. Therefore, this phenomenon has to be taken into account if a well prediction of engine performances want to be performed. Present work aims at giving a contribution to the validation of 3D CFD models for the simulation of the in-cylinder thermo-fluidynamic processes underlying energy conversion, and comparing with settled experimental measurements carried out insight the dynamics and the impact over walls of multi-hole sprays for DISI applications through combined schlieren and Mie scattering techniques.