Converting your Vehicle to LPG

What are the advantages of using LPG?

The major advantage in using LPG is the potential for cost saving – it can be up to 50% cheaper than petrol, litre for litre.

Other advantages are reduced exhaust emissions, longer engine life and in some cases better performance.

Are there any disadvantages?

Yes, there are a few disadvantages to consider. The cost of conversion is probably the major point. Expect to pay up to $3,000 depending on the application. Also, in some cases, the installation of the gas tank in the car’s boot may take up considerable space. LPG is also not as widely available as petrol.

What effect does LPG have on economy and power?

Because LPG does not contain the same amount of energy as petrol, both fuel consumption and power will suffer. However, later model vehicles are generally less affected.

Up to 30% increase in fuel consumption may be expected but this is offset by the lower cost per litre of LPG.

What does an LPG conversion involve?

The conversion itself does not alter the car much: new equipment is added but very little of the existing equipment is changed or removed. All conversions will, however, include a dedicated gas fill point.

During most conversions:

1. A steel LPG storage tank is installed, usually in the boot but it can go under the floor in vehicles with enough clearance (e.g.; four wheel drives). This tank must be fitted with an automatic fill limiter (AFL) which ensures you cannot fill your tank past the safe fill limit of 80%. This is necessary as LPG requires room to expand with temperature changes.
   

2. A converter/regulator is added. This converts the liquid gas into a gaseous vapour, as well as regulating the process.
   

3. A special air/fuel mixer is installed to ensure the correct amounts of LPG and air are mixed together during combustion.
   

4. A fuel lock is fitted that lets fuel flow when the engine is running but shuts off the fuel supply as soon as the ignition is turned off.
   

5. If the vehicle is post-1986 (i.e. built to run on unleaded petrol), it must be fitted with an LPG Fuel Control Processor.

What does dual-fuel mean?

Dual-fuel means the vehicle can operate on either one of two fuels, usually petrol or LPG.

Should I choose LPG only or dual-fuel?

It costs no more to have your car converted to dual-fuel than it does have it converted to LPG only. So if it’s possible, it makes sense to go dual-fuel and give yourself the added flexibility of being able to use two types of fuel.

Post – 1986 vehicles (i.e. those built to run on unleaded petrol) present no problems. With these vehicles, the engine tuning is the same whether it’s running on LPG or unleaded petrol.

Do engines with E.F.I systems operate efficiently on LPG?

Yes, but only provided the equipment to be used is selected carefully. Ensure that it is designed, intended and can be tuned for the particular vehicle. Most, but certainly not all EFI systems, can be converted effectively to either “Dual-Fuel” or “Gas Only”. There are many technical factors which should influence the final decision on type of conversion.

Is much of the vehicle manufacturer’s equipment altered?

No, especially not where the conversion is to “Dual-Fuel”. With the new breed of engine management systems the vehicle emission controls, sensors, catalytic converter and computer modules must continue to function correctly. The new gas control system may need to be interfaced with the existing engine control electronics.

Vehicles must continue to comply with relevant Australian Design Rules and installation must meet Australian Standards.

Some makers, like Ford, Holden, Toyota and Mitsubishi offer factory fitted or approved LPG systems.

How is LPG normally stored in cars?

An LPG container is manufactured to comply with AS 3509 and installed to meet the stringent safety requirements of AS 1425. It is normally installed in the forward area of the vehicle’s boot. The installer should fully discuss the type and size of container that best suits your vehicle when presenting the quotation.

When can I convert?

You can convert your vehicle to LPG any time after the run-in period specified by the vehicle manufacturer or 5000 km after an engine rebuild.

If you are buying a new car and want to run LPG, it’s worth checking to see if there is a factory system available.

Does LPG have an effect on engine wear?

An appreciable reduction in overall engine wear is normal when using LPG. This is particularly applicable during cold starting, because LPG does not wash lubricating oil from cylinder walls.

Modern ULP engines are especially suitable for conversion to LPG. However, you should check
with the manufacturer of your vehicle to ensure that it is suitable for use with LPG.

Will my new car warranty be affected?

Unless it is a factory fit or factory approved system, we recommend you check this with the vehicle manufacturer before converting. Remember also to ensure that the gas installation comes with a warranty covering its fitment, the equipment and any related problems.

Is it difficult to change from petrol to LPG?

No, in most cases it is only necessary to move a switch to change from one fuel to another. Many late model EFI vehicles start on petrol then automatically switch over to gas. Obviously each system is different and operating instructions are usually provided.

Does running an engine on LPG require any special treatment?

No. LPG engines should be serviced just like a normal engine. There are however special engine oils available for LPG engines.

The only point to remember is that in a dual-fuel application it is still necessary to use a petrol regularly to ensure the petrol system components remain in working order.

As a guide, use petrol weekly with a minimum of 20 litres being used every 3,000km. A minimum petrol level above ¼ tank should also be maintained at all times. It’s worth checking with the manufacturer or gas installer for specific instructions on this point.

Can my local garage still service my car after conversion?

Yes, normal servicing is unaffected by the conversion: however, as Queensland has strict controls on the quality of installations, only licensed LPG installers may work on LPG systems.

Is LPG right for me?

The economic viability of conversion will depend on your vehicle's fuel consumption, the number of kilometres travelled each year and the actual difference in price between LPG and petrol. We will show you how to do your own calculations.

Will conversion be cost effective?

The calculation table below will help you determine how much converting to gas will save you and how long it will take to repay the cost of conversion.