A comparative study using diesel fuel and gasoline has been conducted focusing on the injection process. In this paper an experimental study has been carried out comparing the effects of the different fuels on the mass flow rate, momentum flux and spray visualization in non-reactive conditions with a conventional common rail system with a multi-hole injector and two different nozzle designs. Analysis of the results for both fuels show no significant variations of the momentum flux between fuels while mass flow appears to be higher for diesel with respect to gasoline when the injector needle is fully open. The use of gasoline in these injectors seems relevant in the opening and closing phases of the injector. The high-speed imaging under non-evaporative conditions revealed that both diesel and gasoline spray penetration are "quite'' similar and the statistical analysis of the results shows good agreement with the literature, furthermore new parametric correlation for gasoline is presented in this work. No major differences in the spray cone angle have been found either, showing consistency with the momentum flux measurements. (C) 2012 Published by Elsevier Ltd.