At the beginning, all of the experiments were started after running the engine during approximately 30 min until it reached steady state conditions and cooling water temperature became 70 C ± 5 for warming. At 2000 rpm, firstly the load of the engine was adjusted as 149 N m (525 N loading force). Then, carburetor mean jet opening was adjusted to the 1st opening and it was fixed. This opening gives approximately 2% water ratio. Then, tests with approximately 2% WR were performed for loading moments between 149–77 N m;