Autogas Systems – Single or Multi-Point?

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Whilst many autogas systems installed remain the conventional Single-Point mixer-ring type systems, these have now been superseded by more efficient multi-point systems, often incorporating sequential injection technology.

This is necessary for the LPG/Autogas industry to keep abreast of the major advances being made by vehicle manufacturers developing vehicles that conform to the latest Euro III/IV emission standards for petrol engines. The relatively crude mixture control of the early single point systems is no longer able to achieve the low levels of emissions required for the significantly cleaner petrol engines of today, and also cause many engine check light problems on all new vehicles equipped with the EOBD (On-Board Diagnostics) mixture control systems.

Multi-point systems offer additional crucial advantages:

No Performance Restriction

The installation of a mixer ring on the throttle body with single-point systems dramatically reduces the volume of air that can flow – A calculation of a typical mixer ring for a 4.6 Range Rover confirms a massive 70% reduction in the area of the aperture!

No Risk of Costly Backfires

Even the best installation of single-point technology cannot guarantee the system will not backfire. The principle of mixing gas and air at the throttle body means the plenum chamber and inlet manifold will also be charged with the explosive mixture en-route to the cylinders, rather than just the air that the engine has been designed for.

A vacuum leak on the manifold or a spark plug /HT lead problem is all it takes for the system to backfire – often resulting in damage to the vehicle’s air filter housing or air-flow meter.

A word about Plastic Inlet Manifolds

At ACC Autogas we feel it is not our place to decide how you spend your money, rather to present you with sufficient information for you to make your own, informed decision about whether to opt for a single-point or multi-point system, and so long as you make your decision armed with all relevant facts we will be pleased to install whichever system you opt for.

However, more and more cars now incorporate plastic inlet manifolds rather than the traditional alloy variants and these are a particularly bad combination with single-point conversions because they simply cannot withstand backfires. The cost of replacing a shattered manifold will inevitably negate the initial price saving in opting for a single-point system, and also leave you with a bad impression of autogas conversions in general regardless of any fuel cost savings you may have enjoyed.

For this reason we always recommend multi-point systems for such vehicles.