Hydrogen internal combustion engine (H2ICE) easily occur inlet manifold backfire and
other abnormal combustion phenomena because of the low ignition energy, wide
flammability range and rapid combustion speed of hydrogen. In this paper, the effect of
injection timing on mixture formation in a manifold injection H2ICE was studied in various
engine speed and equivalence ratio by CFD simulation. It was concluded that H2ICE of
manifold injection have an limited injection end timing in order to prevent backfire in the
inlet manifold. Finally, the limit of injection end timing of the H2ICE was proposed and
validated by engine experiment.