For the purposes of design of a turbocharger centrifugal compressor, a one-dimensional modelling method has been developed and applied specifically to electrically-assisted turbochargers (EAT). For this purpose, a mix of authoritative loss models was applied to determine the compressor losses. Furthermore, an engine equipped with an electrically-assisted turbocharger was modelled using commercial engine simulation software (GT-Power) to assess the performance of the engine equipped with the designed compressor. A commercial 1.5 L gasoline, in-line, 3-cylinder engine was selected for modeling. In addition, the simulations have been performed for an engine speed range between 1000 and 5000 rpm. The design target was an electric turbocharger compressor that could meet the boosting requirements of the engine with noticeable improvement in a transient response. The results from the simulations indicated that the EAT improved the overall performance of the engine when compared to the equivalent conventional turbocharged engine model. Moreover, the electrically-assisted turbochargers (EAT) equipped engine with power outputs of 1 kW and 5 kW EAT was increased by an average of 5.96% and 15.4%, respectively. This ranged from 1000 rpm to 3000 rpm engine speed. For the EAT model of 1 kW and 5 kW, the overall net reduction of the BSFC was 0.53% and 1.45%, respectively, from the initial baseline engine model.