Nowadays, several researches are being performed to replace diesel oil with alternative fuels in compression ignition engines. Ethanol is a strong candidate, thanks to its extensive raw material, low emissions and low cost. Although it also has easy adaptability to engine technologies, there are some difficulties that need to be eliminated regarding your direct use in compression ignition engines (Diesel cycle). The present work is focused on evaluate the ignition delay of additive ethanol in a four-stroke compression ignition engine, relating to energy efficiency, maximum pressure and maximum pressure variation rate under different experimental conditions. Parameters such as engine speed, load and compression ratio, besides fuel injection time and additive percentage were analyzed in order to find patterns that justify the evolution of macroscopic parameters. For this study, a code was developed in Matlab computer software capable of reading the data from the tests performed at PUC-Rio s Centro de Desenvolvimento em Energia e Veículos. From the data generated, it was possible to prove that the use of additive ethanol can be performed without major modifications to the diesel engine, however, adjusting the parameters mentioned above is essential to optimize the combustion process, increasing the engine s thermal efficiency and reducing emissions.