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
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
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
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:
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.
A converter/regulator is
added. This converts the liquid gas into a
gaseous vapour, as well as regulating the
A special air/fuel mixer
is installed to ensure the correct amounts
of LPG and air are mixed together during
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.
If the vehicle is
post-1986 (i.e. built to run on unleaded
petrol), it must be fitted with an LPG Fuel
What does dual-fuel
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
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
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
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
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
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
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.