THE VLB ENGINE & LP GAS

Low pressure liquid gasses such as methane or propane, are easily and safely stored in reasonably light and small containers. The injection system developed for the VLB engine is also adaptable for these fuels, and is able to deliver the gas to the engine cylinder, still in its liquid form.

Because these gasses are essentially single molecule fuels, they have very precise combustion characteristics, making their dispersion throughout the chamber air predictable, a useable adiabatic zone definable, and spontaneous combustion of the bulk of the charge easy to arrange. In fact, they sound ideal, and so they are, for most purposes.

The LPG injectors and fuel preparation system differ somewhat from their mixed molecule fuel equivalents, but not to any remarkable degree. However, gasoline injectors cannot be used for liquid gas. Having said that, it is practical to fit a vehicle with an 'emergency' gasoline tank, as the LPG injectors will allow reasonable performance from gasoline.

The VLB engine runs well on LPG, provided that no gas is allowed to enter the fuel lines. This means that if the fuel gets low enough to slop around in the tank, misfiring will inevitably result. Steps can be taken to minimise this, but running too low is not a good idea.

An empty tank is fine, as is starting the engine with some gas build-up in the injector supply line. When set up and programmed to use LPG, at switch on, a tiny valve in the injector opens, to allow the gas to escape into the air inlet system, closing when the liquid arrives. No pollution results, since the gas is drawn into the engine and simply 'marginally enriches' the first few charges. The very large excess of air ensures enough oxygen to effect combustion.

To sum up, the standard VLB engine requires only the injectors to be changed, the ECU's program to be set to the type of LPG, and the physical supply plumbing to be changed or modified. The engine itself requires no additional modification.