Low cost LPG Conversions
When I bought my 2.0 16v Scorpio I knew that it would be quite thirsty being
a big car with an automatic gearbox. I also knew that I could easily make the
car affordable by converting it to LPG. I have discovered many benefits with
LPG, smoother running, less emissions, lower fuel costs and of course it
provides the opportunity to run a bigger more luxurious car and still be in
pocket. I nearly went as far as buying a Jag but the cost of spares (and my
Wife) ruled that out. I have only owned my Scorpio for about a month and checked
out the price of the LPG kit and ease of fitting before I made the final
decision to buy.
I had previously converted my Citroen Xantia to LPG and run it for over 8000
miles with no problems, although ironically after fitting the LPG it never ran
quite as well on petrol. That was no real problem though as once youíve paid 35p
for a litre of gas you only run on petrol as a very last resort!
The Scorpio has had no problems with the LPG or when switched back to petrol. I
do not yet have accurate mpg figures for the Scorpio but I am keeping an
accurate check of running costs, which I will give feedback on. One of the best
things about the DIY conversion is that the kit price has come down
substantially. For my car the price including postage was less than £500!
I considered getting one of the new injection kits but the price of these is
still very high at over £1000 and I was also told that there is not one suitable
for the Scorpio. The equipment I fitted is low tech and effectively turns the
car back into a carburettor set-up but works well and gives smoother running
than when on petrol.
There is said to be a loss of mpg and power when on LPG, but by very careful
adjustment over a period of time I found that I was getting the same mpg on the
Citroen when on gas as I had been on petrol (About 28 mpg overall)
As for the loss of power, I never noticed it with the Citroen and havenít with
The car gets better the more miles it does on LPG as the engine starts to get
cleaner, so the fine tuning shouldnít be done until after the first 1000 miles
or so. After that the gas can be leaned off. Also in the winter months when the
weather is cooler and the air more dense it can be leaned off that bit more.
By the way my insurance company werenít interested in the modifications as they
consider LPG to be safer than petrol. I am told some may ask for a certificate
of safety for the installation. Provided that you have made a good tidy job most
LPG installations centres will check the set-up and issue a certificate for
|The LPG kit I used on both cars was bought from Nick at FES
Group in Wales (Tel 01286-882097) Nick is very helpful before and after the
installation, being available also in the evenings. Not that I had many real
problems fitting the kit but it took me a while to understand what the various
items did and how they related to my car. The supplied wiring diagrams are
confusing at first because they have more detail and components shown than you
will probably use in the conversion and they have been translated from Italian
by Nick. The wiring itself is straightforward as long as you take your time to
locate the right connection and understand what does what. Nick was right when
he told me ďThe first car you convert is the hardestĒ
The 2.0 16V Scorpio was quite easy to convert really, there is plenty of room to
fit the components and the work can be spread over a period of time (although
the sooner you get on gas the sooner you start to re-coup your money). If you
take the plunge you will receive a big grey gas tank and a box of wires, clips,
bolts, electrical devices, copper tubing and other strange bits. The planning
should start well before this though, as your first decision will be the size
and shape of the gas tank, (There is a long list to choose from to suit all
vehicles and needs). If boot space is a priority and you have lots of LPG
stations in you area or on your regular routes then a smaller tank will suffice.
You could opt for one of the doughnut shaped tanks that sit in place of the
spare wheel but these cost more, donít hold as much gas and you still have the
problem of what to do with the spare wheel.
|In the Scorpio I opted for the longest tank that would fit
behind the rear seats and still leave me just over half the boot space, this
turned to be an 82-litre tank. You have to allow for the fact that the tank will
only fill to 80% of its
capacity for safety when doing the calculations. That gives me about 14 gallons
of LPG, even though there are lots of LPG sites near me I donít like having to
fill up all the time and ensures I donít have to use that nasty petrol
|By the way though, the car always starts on petrol because, the
gas has to be sucked from the regulator and it takes slightly longer to start on
LPG, if you start on LPG there is a slight risk of a backfire in the air filter
ducting which has been known to damage some components. Once you pull away and
the revs increase, or you rev the engine at standstill, the LPG automatically
cuts in as the revs drop down again. This ensures a smooth changeover from
petrol to LPG. If you run out of petrol you can switch over manually to LPG and
vice versa, but the dash switch is normally left in the central auto position.
|Anyway back to the tank. I began by fitting the tank first,
which again on the Scorpio is quite easy as with a little careful planning the
bolts that go through the boot floor miss any voids or components. The next best
thing to fit is the Gas Regulator and the front shut off solenoid (The system
uses two shut off valves that close off the
gas when the engine is switched off or stalls, for safety) There is room for
both off these under the bonnet next the nearside strut turret.
The next task was to fit the fill point. I chose a round style at an extra
tenner that looks more like a conventional filler point and drilled a big hole
in the wing near the petrol cap. (On reflection I should have fitted it to the
rear bumper at the side, as this would have made my pipe work less complicated).
|I chose to do the plumbing next which is probably the worst job
as you have to uncoil the plastic coated copper tubing and fit it under the car
from rear to front. Itís not too difficult but a bit messy and fiddly trying to
find the right routing. I have found on both cars that there are spare clips
underneath the floor where the brake pipes and fuel lines run, which saves
having to drill for new clips.
You also have to connect the tank to the filler point with slighter thicker
tubing which is less flexible and like all copper tube the more you bend it the
harder it becomes, again plan ahead. The piping to the tank is shrouded in
plastic tubing so that any leaks from the tank fittings are vented out of the
car, so two more holes are drilled in the boot floor at the side.
|The regulator has to be connected into the car heater hoses to
keep it warm and stop the LPG freezing. This is easy enough as all the clips
and pipes are again supplied but ensure you get the connections right so that
there is always a flow, ensuring you connect to a flow and return.
|Wiring is probably best done next. You have to feed the supplied
cables from the tank to the dash for the connection of the rear shut of valve
and the fuel gauge. This is quite easy and just involves hiding the wires under
the trim by the doors.
You need an ignition live and a permanent live supply. (There are both on the
cross strut on the drivers side behind the lower trim) easy to do.
Two connections to the car ECU, one to the coil feed and one to the computer
car ECUís have the ability to constantly learn the best settings for the engine
and monitors and changes these settings many times a second, it then stores the
last settings until we start the car again. The theory is that the car gets
confused when it has been running on gas and we start it on petrol, so we
install a device, which wipes the memory as if we had disconnected the battery.
Personally I didnít fit the device to the Scorpio as it didnít need it and other
than a few seconds every time I start I donít run on petrol so why upset the
cars learned settings.
(The Citroen needed the device as it began to hate petrol) The ECU is easy to
get at once youíve removed the glove box but has to be removed by drilling out
the pop rivets. Take your time making the right connection for the coil. The pin
number is marked on the inside of the connector plug so is very easy to find.
|The only other connections are from the loom of the main LPG
control switch/fuel gauge to the injector emulators, the Lambda sensor and the
front shut off valve and on my car one to a small electro/vacuum device. In the
end there are only four wires that pass through the front bulkhead. Thatís most
of the wiring now
complete (As the Scorpio does not have a fault warning light on the dash I did
not in the end wire in the Lambda sensor relay. It is only there because the
sensor and the ECU can get confused by the sudden change to LPG from petrol and
vice-versa and bring on the warning lamp for a while until the ECU adjusts)
|There are a couple of more jobs to be done that are easy but
need care. The injector emulator device needs fixing to the bulkhead and wiring
into the shut off valve circuit, also the cables from this that connect to and
from the cars petrol injectors.
As we no longer need petrol squirting into the engine when on gas this device
shuts off the supply for us.
The last items to be fitted are the mixers that mix the LPG as it enters the
mouth of the throttle body and then the rubber gas pipe from the regulator to
the mixers. There is a small branch that splits the pipe into two which also
acts as the gas mixture adjusters, these need to be open about one and a half
|There is a fiddly job to be done now on the 2.0 16v. It involves
removing the idle valve from the top of the throttle body and drilling a hole
where shown in the instructions, much care has to be taken to open the hole up
gradually so as not to do any damage to the throttle butterfly valve. (Or get
someone to hold the throttle open as you drill.
The instructions say that this job is necessary but Nick told me to try the car
first and only drill the hole if the car would not idle. I found the car would
idle but there was a hesitance to pick up from idle and drilling the hole cured
it. With care itís any easy job.
All of this can be done in a weekend but I spread it over two and the car was
still useable throughout.
The car would cut out when on the overrun. I had read of this problem elsewhere
and thought I had the answer which Nick confirmed, Ram air effect. Even though
the throttle was shut, the ram air effect at the mouth of the air filter ducting
in front of the radiator was causing gas to be sucked out of the gas regulator
giving an over-rich mixture. It was easily cured by removing the ducting up to
the point where it goes behind the plastic shroud by the nearside headlight.
As I said at the beginning, I am still setting this conversion up but am
expecting to get somewhere near the MPG figures I had on petrol. I only ran a
couple of tanks of petrol through the car before the gas conversion but estimate
I was getting about 28 mpg. I worked out some figures when I had the Citroen and
reckoned that even if petrol prices continued to fall by a couple of more pence
and I lost as much as 5 mpg when running on LPG I would still be saving a
minimum of 40% on fuel, in the event I saved about 45%
A DIY conversion to LPG is well worth the time and effort and when you sell the
car there will be lots of interested buyers. Alternatively you can remove the
main components and re-use them on your replacement car.
There are lots of web-sites offering conversions (at great cost) and several
sites that list all the LPG sites in UK and Europe many give excellent
explanations of the benefits of LPG.
Did I just hear on the news that petrol prices have begun to rise again? Who