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183 XJ6 (XJ 40) conversions completed

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Go LPG Conversions - Jaguar XJ 40 ( XJ6 ) range



Jaguar XJ 40 (XJ6) 4.0, 3.6, 3.2 and 2.9 - Seriously cheap cars to run!

The XJ40 range may be a little dated now, but good, usable examples can be bought for less than a thousand pounds. Spares are relatively cheap and it is feasible to run one on supplies from the breaker's yard. Even low spec. cars bristle with features. Good roadholding and comfort can be found in all models whilst good performance is given by all but the smallest engine option. The very 'top end' of the market does not go much above 5,000, buying you a late fully optioned car with low mileage and full service history.

Early (pre '92) XJ40 models do not have a catalytic converter and only require an open loop conversion for proper operation.

Later XJ 40 models (roughly 1992 onward) are catalysed, demanding a closed loop LPG conversion, but there is little (if anything) to be gained from fitting multi point gas injection. Closed loop single point systems do a perfect job on this car so the much higher price of multi point conversions are avoided.

We developed our own and quite unique gas mixer for this car, which bought huge benefits in reliability and performance.Go LPG have converted over 100 examples to date, some having done mileages in excess of 30,000 on LPG with no problems at all.

Recently (June '04) we have decided to include a vaporiser temperarture sensor on all XJ40 and X300 conversions, ensuring that gas cannot be selected when the engine (and its coolant) are cold. This removes another potential risk of backfiring, the frozen vaporiser (see 'LPG motoring hints') on the left bar.

Our conversion customers vary enormously in the ways they use their cars and the mileages they cover, but all agree on one thing - Performance of the XJ 40 on LPG is every bit as good as it is on petrol, whilst they save at least half of their fuel costs.

We do, from time to time, have already converted Jaguar cars for sale. Click this link to see what we have right now - Converted Cars for Sale

Safety first

We use Italian market leader OMVL Open and Closed loop equipment

We include all of the latest safety features in every job, one of the reasons we are rarely the cheapest when quoting a conversion price. We don't mind that, and would rather not do a conversion than send one out with less than the full safety measures.

Read up on our conversion procedures - Our standards

If you have any concerns about increased fire risk when a car is converted to run on gas, take a look at this item on a car we converted which later caught fire due to a car related electrical fault - Jaguar fire

Go LPG XJ40 conversion number 104 - Fraser Kings' 4 litre Sovereign, completed 21st November 2003
Go LPG XJ40 conversion number 108 - Vincent Handfords' beautiful Daimler 4 litre, converted 21st April 2004.


Conversion of the XJ40 ( AJ6 engine ) and X 300 ( AJ16 engine )

We have a lot of experience converting both of these Jaguar models. We are often asked to rectify faults with LPG conversions or Petrol faults caused by incorrect conversion.

The AJ6 / 16 engines are not the easiest to convert properly, although many profess to get perfect results. We beg to differ, judging by some of the cars we are asked to put right. I have to say that we have not seen one single properly converted XJ 40 to date, although there must be some good ones out there somewhere.

In fairness, the convertor is often let down by sub standard equipment or plain unavailability. He or She may then be pushed into using inappropriate conversion items and Backfiring is often the result. When it happens, backfiring not only disables the car on LPG, but often on Petrol too, making it impossible for the driver to limp home on Petrol. This is totally unacceptable to us.

Incorrect mixers cause blowbacks 
and this sort of damage. The car will
also not run on Petrol if this happens. Incorrect conversions often result in
blowback (backfiring), damaging the inlet
'Bellows' and allowing unmetered air
into the system. This leaves the engine
unable to run on either Gas or Petrol.
Go LPG! customers do not have to
worry about this. We eradicated the
problem and no one gets stranded.

To address the problem we spent 3 months dealing with the main culprit, the 'one size fits anything' mixer which often proves to be of no use at all. The result of that research and development, (our own specially produced mixer unit) removes all of that compromise, bringing optimum performance, economy and RELIABILITY to these cars whilst running on gas. AJ6 or AJ16 conversion owners can now drive their cars confident that they will not backfire when pulling away etc. The risk of damage to the Bellows, Airflow Meter or other inlet tract components has been completely removed by our unique mixer design. None of our owners have ever been stranded as a result.

We don't sell any of the conversion refinements we have developed to any other company, and hope you will understand why we don't show or describe them here. We do, however, use them on every Go LPG! XJ40 ( AJ6 ) or X 300 ( AJ16 ) conversion and assure you that backfiring will not be something you are familiar with when we have converted your car.

As specialists in our field, we are indeed a little more expensive than the many ordinary Garage businesses who pick up LPG conversion as an 'add on', but you just don't get Champagne at Lemonade money, it really is as simple as that.


Here are a few pictures of the Go LPG! XJ 40 conversion -

XJ40 conversion number 162 - Our own manual transmission car.

It runs for roughly the same cost as a Ford Escort.

The fuel choice switch fits neatly into the coin pocket. Nice and easy to reach but does not interfere with your night vision.



NOT the way to do it (in our humble opinion)!



Picture on left - Showing the most popular tank option, the 90 litre cylinder. Good, usable boot space remains. Notice the spare has been moved from its original vertical position and lain down on the boot floor. On post '92 cars the battery and its mounting must also be moved downward, requiring the positive battery lead to be lengthened.


Picture on left - Shows the 70 litre cylinder tank option, for those who want more boot space but can accept less LPG range.

An interesting point is that spare wheel replacement (Toroidal) tanks do not bring much space benefit to the XJ 40 boot, they also have a smaller capacity but cost twice as much. Our advice is to stick with the cylinder.


Lower 2 pictures on left -

NOT the way to do it (in our humble opinion)!

Although this is the same size tank (90 litre) as shown in our top picture, the owner of this car (converted elsewhere) can barely squeeze anything inbetween it and the spare. The boot space is virtually useless whilst the tank itself is prone to damage in a rear end impact. We wouldn't feel safe with a tank placed here, nor do we expect you to.


The last picture on the left shows another half-hearted attempt at fitting a 90 litre cylinder. Once the spare has been carelessly attached to a tank bracket ( against LPGA rules) it renders the remaining boot space practically useless.

Filler points


Nowadays, LPGA regulations call for the use of filler types that need no adapter for use in UK, effectively banning the use of adapter/filler arrangements. The recommended fixed bayonet filler (centre of picture) is mounted on a bracket fitted to the rear bumper on the XJ40. This is one of the only positions that will conform to regulations but remain easy enough to use. A coil is put in the pipe to prevent it rupturing during a rear - end shunt, but even if it pipe where completely severed the multi valve would stop any significant (large scale) leakage. All that can happen in that case is the escape of pipe content since the last fill, rarely more than 30 or 40 millilitres.



The lower picture shows another option for XJ 40 filler positioning. Although more expensive, this recessed type of filler point does not need an adapter for use with UK filler pumps. We'd prefer not to cut holes in your shiny rear wings and the weight of the LPG filler gun can buckle the panel, but it does provide a filler point that is much easier to use, especially for the ladies. It is now offered as a customer choice.


Here is a third option, mounting the filler on a towbar.

(Requires towbar!)

The Go LPG! XJ 40 (XJ6) Conversion

Uncatalysed Cars (Normally built before 1992)

2.9, 3.2, 3.6 or 4.0 require an OPEN LOOP conversion.


Catalysed Cars (Normally late 1992 onward)

2.9, 3.2, 3.6 or 4.0 require a CLOSED LOOP conversion.


For an explanation of these requirements and full description of different types of LPG conversion, visit Which conversion?


To date ( 21/ 11/ 03) we have converted 104 examples of the XJ 40 and not one of them has had a single backfiring occurrence. This will continue throughout the life of the car as long as it is kept properly serviced and maintained. Peformance on LPG is practically identical to that of petrol. 12 months parts and labour warranty is given with every job, along with a nationally recognised insurance certificate.

Contact us to arrange the conversion of your XJ40

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LP Gas burns cleanly.....

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Click here to get a quote for the conversion of your vehicle