Induction Systems LPG Kit This type of system is the simplest and by far the most common conversion carried out. Suitable for all types of vehicle, the system introduces gas to the engine in a vapour form through the inlet manifold. Older, carburettor vehicles and early, injection models use the LPG Kit reducer to control the inlet of fuel into the engine. Later vehicles use a slightly more sophisticated management system that reads the oxygen sensor in the exhaust. This then controls fuel levels using a stepper motor, which gives the most efficient fuelling at all times.