... minimise engine emissions and safe knock limit by changing some operational and design parameters such as equivalence ratio, spark plug location, compression ratio, and cylinder diameter by ... speed and 360 bTDC spark timing. These figures illustrate that NO and CO concentration levels increase by increasing XDS value and compression ratio. XDS is the ratio of cylinder diameter and ... Valiev and L.E. Eriksson. Numerical Modeling of the Propagating Flame and Knock Occurrence in Spark-Ignition Engines. Combust. Sci. and Tech., 177: 151-182, 2005. [21] J.C. Livengood and P.C....