In this study, a four-stroke carburettor spark-ignition (SI) engine was run using a specially designed, electronically controlled gas-phase manifold liquefied petroleum gas (LPG) injection system in a set of experiments conducted to compare the performance of different fuels and mixing systems. Experiments were carried out at 2000-4000 rpm and fixed throttle positions of 25% and 50% of full opening to determine performance parameters. During the tests, carried out in a test bed with a specially designed, electronically controlled LPG injection unit, the excess air coefficient was maintained within the range of 0.95-1.05 because the best emissions results are generally obtained in this range. The results obtained with LPG injection were compared with the results obtained for gasoline and LPG carburetion. The test results showed that the LPG gas injection system developed in this study can help to achieve higher engine power outputs, lower specific fuel consumption and lower exhaust emissions. Crown Copyright (c) 2013 Published by Elsevier Ltd. All rights reserved.