Optical characterization of bio-ethanol injection and combustion in a small DISI engine for two wheels vehicles

► We performed optical measurements in a GDI engine for two wheels vehicles. ► We investigated two injection pressures in two engine condition using two fuels, gasoline and pure ethanol. ► Gasoline spray was more sensible to changes in injection pressure than ethanol's. ► At low speed and load ethanol combustion showed faster burning rates and so higher peak pressures than gasoline. ► Ethanol combustion shows less diffusive flames than gasoline, associated with lower levels of soot.