Effects of ozone addition and octane sensitivity on combustion characteristics of gasoline compression ignition engines

•Ozone seeding and octane sensitivity significantly affect the combustion of GCI engines.•High octane sensitivity enhances low- and high-temperature combustion and heat release.•Ozone seeding initiates more reactive radicals and induces earlier combustion phasing.•Ozone seeding reduces combustion disparities under various octane sensitivity conditions.