However, as can be observed from Table 6 that for loads of 132 N m, 103 N m and 89 N m at 3000 rpm effective efficiency increases slightly with (4–10%) water additions compared to NDF. As previously stated, water injection in the intake air does not show any significant change in the bsfc and effective efficiency of the engine for selected loads and water ratios at 2000, 2500 and 3000 rpm. Similar tendency has also been reported by earlier researcher [4,18]. As can be seen in Fig. 5d that, for all of the loads at 3500 rpm, effective efficiency increases approximately at the level of 4% by WI.