The results of the simulation and the test stand investigations of the 170.A1 engine fed by the injection of a liquid phase of propane-butane or pure propane and pure butane have been reported in the article. A modified serial single point gasoline injection system and an engine controller of own design engine have been used and discussed. The Comparison of selected engine parameters for given cases of fuelling confirmed the possibility of the use of the evaporating heat of fuel to improve the cylinder filling. The effective parameters of an engine fuelled with pure propane or pure butane were more beneficial than for gasoline fuelling.