How It Works

The heart of the system is the ECU – the Engine Control Unit.

Click here to view a larger version of the system diagram.

The ECU measures engine parameters such as rpm and load. It has an advanced Digital Signal Processor which produces a 3D map to determine the exact amount of LPG gas which should be added to the engine. The ECU then opens the gas valve to the precise position to inject the LPG gas under pressure into the engine manifold, where it mixes with the air.

The diesel engine draws the air/gas mix into the cylinder where it is compressed, and then the engine injects diesel which ignites, burning the LPG gas at the same time.

Because engine power increases the engine’s own electronics thinks that too much diesel is being injected and throttles it back. The total amount of fuel being consumed goes up slightly, and engine power goes up slightly, but because an amount of diesel is replaced by cheaper LPG the fuel costs come down.

Installation

Fitting is very easy.

First of all the ECU, the electronics which control the whole system, is fitted (usually in the cab). The valve which controls the flow of LPG vapour and a reducer which converts liquid LPG into vapour are mounted in the engine bay. The LPG tanks are fitted within the chassis.

Two small holes are drilled into the manifold, one to sense manifold pressure and one to inject the LPG gas. A knock sensor is also mounted on the engine block.

After that the electrical items are all connected together and the various LPG liquid and vapour hoses are connected, and the system is installed.

The beauty of this installation is just how little it interferes with the engine and how few modifications are made to the engine.