A system for an engine, comprising a cylinder located in the engine, a turbocharger coupled to the engine, a first injector for injecting a first fuel into said cylinder, wherein said first injector is a direct cylinder injector where said direct cylinder injector delivers a liquid including an alcohol, a second injector for injecting a second fuel into said cylinder, wherein said second injector is a port injector, where said port injector delivers a liquid including gasoline, a catalytic device configured to receive exhaust gases produced by at least the cylinder, and a controller configured to vary an amount of said first and second fuel injection during engine operation based on operating conditions, where amounts of variation of said first and second fuels are set to maintain a substantially stoichiometric mixture, the controller further configured to increase a relative amount of injection of the second injector in response to an indication of engine knock during a first operating condition, decrease engine boosting in response to the indication of engine knock during a second condition; and retard ignition timing in response the indication of engine knock during a third condition.