Abstract:The use of hydrogen as an engine fuel has great potential for reducing exhaust emissions with the exception of a small amount of carbon containing emissions originating from the lubricating oil, NOx is the only pollutant emitted. In this paper by using a turbulent flame speed method, a quasi-dimensional thermodynamic model of an SI engine fueled with hydrogen is developed. In this work, simulation results are validated by experimental data. Then the effect of spark advance, A/F ratio and valve timing on emission and performance characteristics of the modeled engine has been investigated. Hence, remarkable effects in emission and performance characteristics observed. And the behavior of the modeled engine against the above parameters has been investigated and the reason of that is discussed.