: In order to investigate the effect of ignition advance angle and LPG injecting methods on an LPG engine performance, three methods of injecting LPG were tested on an LPG engine. The injection methods were gaseous phase LPG injection at intake port, liquid phase LPG injection at intake port, and liquid phase LPG in-cylinder direct injection. The maximum torque developed with liquid phase LPG engine direct injection, was 12.6% higher than gaseous phase LPG injection at inlet port. The ignition advance angle clearly affected LPG engine torque and emissions. The optimum ignition advance angle for LPG engine torque was about 26º CA. The LPG engine emitted many HC and CO emissions when the ignition advance angle increased greatly.