Patent ID: 7784443

Claim:
A spark-ignition gasoline engine having at least a spark plug and using a fuel having a research octane number (RON) of 91 or more, comprising: an engine body having a geometrical compression ratio set at 13.5 or more, said engine body being operated using a fuel having a research octane number (RON) of 91 or more; an intake valve and an exhaust valve which are provided, respectively, in intake and exhaust ports connected to each of a plurality of cylinders of said engine body, said intake and exhaust valves being adapted to open and close corresponding ones of said intake and exhaust ports; operation-state detection means adapted to detect an operation state of said engine body; and control means adapted, based on detection of said operation-state detection means, to perform at least an adjustment control of an ignition timing of said spark plug, said control means being operable, when the engine operation zone is a high load operation zone including a wide open throttle region, within at least a low speed range, to retard said ignition timing to a point within a predetermined stroke range just after a top dead center of a compression stroke.