Go LPG! Research
172 XJ6 (X 300) conversions completed

Go LPG Research - Jaguar X 300

Jaguar XJ6 ( X 300 ) 4.0 and 3.2 - Seriously cheap cars to run!

X 300 conversion number 100 - Our own Daimler Six LWB

The X 300 is often called the last 'true' Jaguar. It has all the best attibutes of cars past in one model. The traditional Jaguar designed 6 cylinder in-line engine (AJ16) was a development of the monumentally reliable XJ40 AJ6 unit. Although the X300 bodyshell is very similar (doors are interchangeable for instance) the angular XJ40 style bodywork has gone, curvaceous Jaguar body styling returned to mirror earlier models. Significant improvements in drive quality and performance were made over comparable sized XJ40's. Experienced Jaguar Enthusiasts will tell you that the car drives more like the older Series 3 XJ6 which was rather special, if unreliable. The AJ16 Engine and 4 speed automatic gearbox combination is well know to be 'bombproof' with some examples now close to 400,000 miles without incident. Secondhand AJ 16 engines and gearboxes are easily found because they rarely get sold - No-one ever needs one!

X 300 conversion number 172 - Beautiful Daimler Six LWB brought all the way from Edinburgh for conversion.

All of the X 300 models are catalysed, demanding a closed loop LPG conversion. There is just a little to be gained from fitting a multi point gas injection system. Closed loop single mixer systems do a perfect job on this car (as long as they are properly installed) although a multi point system will remove any risk of backfiring due to igntion faults and give almost total automation of fuel switchover. Go LPG have converted many X300 examples to date, some having done mileages in excess of 60,000 on LPG with no problems at all in either system.

The X300 has only a few problems to watch out for, the most important being the tendency for rear axle noise in high mileage examples. Watch out for this if buying a car, it is very expensive to repair. At the other end of the scale, in terms of seriousness and cost. one rarely sees an X300 digital clock that actually works. Corrosion is not really a problem although wheel arches that have been shotblasted by road grit for thousands of miles can show blistering or loss of the angled edges.

As we have a lot of experience with the X300 model we have described the most common faults to watch out for when buying one - Common X 300 faults

Getting back to LPG, our Jaguar conversion customers vary enormously in the uses they put their cars to and the mileages they cover, but all of them agree on one thing - Performance of the X 300 on LPG is every bit as good as it is on petrol whilst they save half of their fuel costs. Overall fuel economy on LPG (Mixed Town and Motorway) has been estabilshed as 20 mpg over millions of miles. Use the difference in price of petrol and LPG to come up with a conversion factor (e.g. 2.3x) and you'll likely discover that LPG X300 owners are enjoying equivalent fuel economy exceeding 40mpg.

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

Here are a few pictures of the X300 conversion -

4.0 litre X300 in nice condition, now taught the economy trick.
The fuel choice switch fits neatly into the coin pocket. Nice and easy to reach but does not interfere with your night vision.
Some choose the single hole 70 litre spare wheel replacement (toroidal) tank to preserve boot space. A 70 litre tank holds around 56 litres of LPG.

For a modest increase in cost we can fit an 88 litre single hole toroidal tank.

For those that need increased range on LPG we now offer a 4 hole toroidal tank having a water capacity of 91 litres ( actual LPG capacity circa 75 litres). This option does have additional cost.

Filler points

Bumper mounted filler

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 X 300 model. 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 bumper filler with dust cap in place

Recessed box filler

This picture shows another option for X 300 filler positioning. Although more expensive, this recessed type of filler point also does not need an adapter for use with UK filler pumps. We'd prefer not to cut holes in your shiny rear wings and note that 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.

Note that there is a hidden disadvantage in having a filler mounted on one side of your car - You have to wait for the chance to get to an LPG pump on the same side as your filler. If you have a rear mounted filler like the one on the bumper above, it is likely that you can use a pump from either side. This can be a great benefit on a tight garage forecourt.

Find out more about Filler Points

Here's a third option, mounting the filler on a towbar.

(requires towbar)

Conversion of the X 300 3.2
and 4.0 litre 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 X 300 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 simple inavailability. He or She may then be pushed into using inappropriate equipment, 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.

Suggested link - X300 conversion in under an hour

Go LPG X 300 Conversion

3.2 or 4.0 models require a Closed loop conversion to protect the catalytic converter.

This can be either a Closed Loop Single Inductive Mixer system


a Multi Point Gas injection system.

Closed Loop Single Inductive Mixer System

All of our X 300 conversions benefit from our own specially developed mixer unit which is not available anywhere else in the world. To date we have converted many examples 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.

Multi Point Gas Injection System

As time moved on these systems have become cheaper and better. We now offer alternative multi point systems from just a couple of hundred pounds more than an inductive mixer system. They do give the benefit of more automation and remove any risk of backfiring if an ignition fault were to develop.

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