shown in figure 4. The average increase in brake thermal efficiency for0.5 of water to fuel mass ratio is approximately 2.4% over the use of LPGalone for the engine speed range studied.The variation of the exhaust gas temperature with engine speed forthe different water to fuel mass ratio is shown in Figure 6. It is clear thatas the water to fuel mass ratio increases, the exhaust gas temperaturedecreases. The heat absorbed by the additional water can explainthe decrease in the exhaust temperature, because latent heat of thewater will lead to absorb heat and so cool the charge. Lower exhaustgas temperature is an indication of a lower mean cycle temperaturetemperature through the engine cycle.