Effects of biodiesel–gasoline blends on gasoline direct-injection compression ignition (GCI) combustion

•Combustion effects of biodiesel addition to gasoline are analyzed in a light-duty diesel engine.•Biodiesel content at 5% and 10% levels reduced ignition delay and intake temperature requirements.•CO oxidation is shown to be enhanced by increased bulk gas temperatures.•Oxidation of CO was not enhanced by increased oxygen content of biodiesel blends at matched phasing.•Varied ignition delay times are inferred to have an impact on mixture strength and therefore on UHC.