This study is to examine the performance of diesel engines with dexlite and diesel fuels. The problems in this study are: There is no practical tool for testing diesel engine performance with dynotest load, The effect of time and load variations on dynotest on the performance of Common Rail diesel engines with dexlite fuel, The relationship between torque and fuel consumption, engine speed, and efficiency in testing the performance of Common Rail diesel engines with dexlite fuel. This type of research is experimental research with experimental groups. The results of this study indicate that the practical tool for testing performance on diesel engines with dynotest has been successfully made and can be used for testing the performance of diesel engines with different fuels. The test results show that the longer the test time, the higher the efficiency, and the more load given, the higher the efficiency. Comparison of the relationship between output power and fuel consumption, engine speed and efficiency can be concluded that the greater the output power, the greater the fuel consumption required by the diesel engine, the greater the output power, the engine speed will decrease, and the greater the output power, the greater the efficiency. The results of the comparison of the relationship between torque and fuel consumption, engine speed, and efficiency can be concluded that the greater the torque, the greater the fuel consumption required by the diesel engine, the greater the torque, the engine speed will decrease, and the greater the torque, the greater the efficiency.

Keywords: Dexlite, Dynotest, Diesel Engine, Torque, Fuel.