© 2018, Springer-Verlag GmbH Germany, part of Springer Nature. In the last decades, the need of cleaner and renewable fuels has increased the use of alcohols to power internal combustion engines. The ABE (acetone–butanol–ethanol) method to produce purified biobutanol and bioethanol is the most known and well-studied method to produce those alcohols. Nevertheless, it is not yet clear how the bioethanol’s content in the biobutanol stream could affect the engine’s biofueled performance. Thus, this study focuses on (1) the performance of an internal combustion engine and (2) on the different compositions of n-butanol/ethanol mixtures, up to 20 vol%, to assess the operative issues of the use of both alcohols instead of pure n-butanol. In order to get the most reliable results of the engine’s performance, we conducted three different experiments for each alcohols’ composition, including conventional gasoline testing as reference. The experimental tests were carried out in a CT 150 Internal Combustion Engine Basic Module and conducted at various speeds—from 700 to 1500 rpm—resulting in load variation. In general, the changes in the composition of ethanol in n-butanol do not seem to affect the performance of the engine considerably, as variations occur at an approximate rate of 3.7% in effective power, 3.3% in torque and 5.4% in specific fuel consumption.