What is an LPG Conversion?
An LPG conversion involves the installation of a secondary fuel system. Below is a guide to the components that are installed in the vehicle with a basic description of their function.
The LPG Tank
As the LPG system is separate to the petrol system, it requires its own fuel tank. This is normally a toroidal (dougnut) shaped tank, fitted in place of the spare wheel so there is no loss of boot space.
For a small number of vehicles, a cylinder tank may be the only option. Both toroidal and cylinder tanks are manufactured in many sizes.
LPG drivers carry a can of ‘tyreweld’ so the tyre can be re-inflated
quickly, easily and safely in the event of a puncture or carry their
spare wheel seperately so they are able to create more boot space if
To fill the tank, a filler point is mounted to the exterior of the vehicle, usually in the body work, the bumper or fixed to tow bars.
The filler cap can be sprayed to match the vehicles paintwork, although not all installers offer this service.
Under the Bonnet
The LPG passes through a ‘reducer’ to vaporise the LPG before it reaches
the engine. This is controlled via the LPG ECU, calibrated to match the
same level of power and performance of the petrol system.
The gas is fed into the manifold through the LPG injectors. There is
an LPG injector for every petrol injector. During changeover, the LPG
injectors open sequentially as the petrol injectors close to give a
smooth and unnoticeable transition.
Inside the Car
The vehicle will start in petrol and switch over to LPG automatically. Should you run out of LPG, the system will revert back to petrol whilst you are driving. The changeover is smooth and unnoticeable.
A small switch is installed inside the vehicle which allows the driver to changeover manually. There are normally a number of options as to where the switch can be positioned.
An LED located at the top of the switch informs the driver when the vehicle is running on petrol (red) or LPG (green). The light will temporarily be orange during the changeover.
There are 4 lights at the bottom to indicate the level of fuel in the LPG tank.4
lights = full tank, 3 lights = 3/4 full, 2 lights = 1/2 full, 1 light =
1/4 full & 1 light (flashing) = reserve level of LPG