It's cheaper than petrol, so the running costs are lower, and it's cleaner, and the great thing about today's high-tech injection systems is that there is no loss of performance.
The gas revolution began in 2003 when LPG system manufacturers were required to comply with the OBD, On Board Diagnostics, requirements laid down in our exhaust emission laws. To comply they had to be able to isolate the operation of individual cylinders, something that was impossible with the old venturi/mixer systems that had been in use since the 1970s.
They also had to be able to isolate individual cylinders to be compatible with other systems on the cars, such as Traction Control and Electronic Stability Control. Without such control Ford hasn't been able to fit its dedicated LPG cars with electronic stability control.
While the old systems could be made to work perfectly well on the older cars and are still being fitted today to older models by owners wanting to save a few bucks at the bowser, they weren't suitable for newer cars under the new laws.
That was the main motivation for the move to the sequential-injection systems that are now being used. The main sequential injection system in use injects vapour into the engine in much the same way as sequential petrol-injection; the gas is injected through a dedicated LPG injector in the intake port near the intake valve.
As a result the quantity of fuel injected is accurately controlled, and because it's done near the intake valve, the intake manifold isn't filled with an explosive mixture of air and LPG, which reduces the possibility of a backfire to almost nil.
Holden uses a sequential vapour-injection system on its Commodore and Colorado models. When Ford eventually introduces its new dedicated LPG system it will be a sequential liquid-injection one, but test cars have been on the road for at least five years, which suggests there have been issues with its development.
HSV also uses a sequential liquid-injection system, but in HSV's case it's a dual-fuel system rather than a dedicated gas system like the one Ford will use.
The proponents of Liquid-injection claim it to be a more efficient system as the LPG is injected as a liquid the same way the petrol is injected, but those who favour vapour-injection say their system is more accurate and not subject to issues with cylinder bore wetting, or underhood vapour-lock problems or refuelling issues that they claim can affect liquid systems.
Both systems deliver the same driveability as an engine running on petrol, and also the same performance.
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