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LPG - Bobbin Threadbare

I have come across a 1980s Jaguar XJS for sale which has been converted to LPG. I'm intrigued by the car and I'd like to go and look at it.

Does anyone have LPG? It wouldn't be a problem round my way with filling it up; there's several stations with it.

I've got my own list of pros and cons with this car and I would like to know what you lot think as well! Before anyone shouts at me and says 'do not buy - car from hell' this is pure curiosity.... ;-P

LPG - unthrottled

Is it the V12? The V12 is a 2 valve engine and they will suffer rom valve seat recession and burned intake valves much more than the 4 valve 6 cylinder. It's not really a suitable engine for conversion, which is a shame because it is in most need of it!

LPG - jamie745

Am i right in saying LPG burns quicker due to it being somewhat "watered down" compared to petrol so actually your mpg isnt as good, but obviously it costs half as much?

LPG - unthrottled

No. Your mpg isn't as good because there's less of it in a gallon. If you take 1 lb of diesel, 1 lb of petrol and 1 lb of lpg, they'll all give roughly the same amount of energy when burned.

LPG - jamie745

I thought a gallon was a gallon. Basic cornerstones of my life now being ripped apart.

LPG - unthrottled

A gallon is a gallon, but the mass of fuel contained in the gallon depends on its density. Diesel has a higher density than petrol which has a higher density than lpg.

That fact alone counts for 10% of the better economy of a diesel car. They're only about 20-25% more efficient than petrols, but the higher density of the fuel flatters the figures.

LPG - jamie745

I got to "mass of fuel" and then fell asleep.

Thanks for trying to explain it but i just cannot spare vital brainspace for it LOL!

LPG - Xantiaman

I ran a V6 Mitsubishi Galant for over 100k on LPG.

Most sites seems to quote a 10% reduction on mpg compared to petrol, my experience was that it was nearer 20%. In my case still worth doing.

LPG - unthrottled

20% is about right.

10%?? Perhaps if you milled the heads to a 13:1 compression and remapped the ignition timing!

LPG - Westpig

It wouldn't be a problem round my way with filling it up; there's several stations with it.

Farms and what have you often have LPG as well. I used to help a mate out who is a balloon pilot. When he was operating away from home, he'd get a list of venues that sold LPG, some of which were most remote. It wouldn't be out of the ordinary to be filling up loads of bottles and then have an old Volvo estate or whatever turn up for its' re-fill.

LPG - unthrottled

I'm puzzled as to why farmers would use lpg when they can buy red diesel for farm equipment which is easier to store.

How does one pilot a balloon?! I thought you were pretty much at the mercy of the wind!

Jamie-why ask a quuestion if you're not interested in the answer. And only Clarkson thinks ignorance is a virtue.

LPG - jamie745

I was interested, but then it got into nonsense i didnt understand so whats the point in reading it? I like to work on a need-to-know basis. I dont know how my engine works, because i dont need to know. Theres qualified mechanics who's job it is to know such things, its what they're there for.

LPG - unthrottled

Density is not a difficult concept though, is it?

Thought you might like the bit about petrol/diesel since you must be one of about 4 people that still hanker after big petrols!

LPG - jamie745

Even at 137.9p a litre i still dont intend to switch to a tractor with heated screens any time soon.

LPG - bathtub tom

I thought the usual answer to LPG was don't, unless it was a manufacturer option and then it was shouldn't.

LPG - Bobbin Threadbare

Thank you all for your thoughts!

The Jag in question is a 6-cylinder manual. I understand that converting to LPG drops the value of the car and it's for sale quite cheaply. What appeals is the fact that the owner has basically decided to undertake an experiment and he says he commutes in the car.

LPG - unthrottled

A manual XKS! They're as rare as hens' teeth! At least it'll stop Jamie getting his grubby hands on it. What's the owner's 'experiment'? Is he selling it?

I doubt that an LPG system would degrade the value-most big petrols have got them installed. On current prices, you save about a 25%* compared to petrol-not the 50% commonly touted by LPG fans.

*based upon :

LPG:75p/litre-corrected to £1/litre to account for lower calorific value

petrol:130p/litre

difference=30p/litre~25%

LPG - Bobbin Threadbare

He was selling it and I was going to have a look (the LPG is the experiment really and he'd upped a 3.6L petrol engine to a 4.0L LPG engine - says the drive is better) but alas it has been sold :-(

Edited by Bobbin Threadbare on 16/07/2011 at 12:42

LPG - Ethan Edwards

I run both my current cars on it. I've used LPG without incident for just under five years. Doing 20K a year. Easy to live with it saves me shed loads. Every time someone moans about the price of petrol I smile inwardly and chucklle. Search the threads BT for LPG and you'll find it's a subject that comes up every time the Government or the oily barons decide to rape the motorist yet again.

LPG - unthrottled

Can't really blame 'big oil' for government tax grab or consumer demand. lpg works well on cars with hard valves and seats-it doesn't on cars that are marginal on unleaded.

The snag is that once the volume of lpg sales reach a non negligible proportion, the government will simply close the loophole. I've seen quite a few newly registered flex fuel vehicles on the road recently...

LPG - Westpig

How does one pilot a balloon?! I thought you were pretty much at the mercy of the wind!

There's more directional ability than you'd imagine, something like 20% from memory, although i'm no expert by any sense of the imagination. It depends on your altitude, because the wind does different things at differing heights.

LPG - gordonbennet

That Jag probably not the best car in the world to be converting, you need basic long term reliability as the investment takes years to recoup if ever.

My MB is LPG'd, 3.2 24v straight 6, it runs sweeter on gas than petrol. Will i make a profit, i don't know. It's allowed me to keep and use daily a car i enjoy, at between 17 and 24 mpg depending on use it wasn't viable without the conversion.

Each time i fill up (at 70ppl) i get that lovely feeling of not giving the thieves at Westminster any more tax than i have to for them to fritter or give to foreign dictators.

Don't buy LPG from service stations, rip off prices, search on one of several sites for an out of the way gas supplier that also sells autogas, they are in most areas.

LPG - concrete

I took part in an experiment with a dual fuel car some 15 years ago. It was a Vectra factory built car with petrol/lpg systems. I ran it for 6 months with about 15K miles done. Then handed it over and got my first diesel company car, a Peugeot 406. The Vectra was fine to drive, although the seats weren't the best. The company accountants did the calculations and the company never bought another LPG car. We ran over 50 cars, so running costs were critical and I was told that LPG/Petrol did not work out in our favour. We also went entirely to diesel for the fleet. Maybe the economics are more favourable now for LPG but knowing our company accountant at the time, if it had been financially viable we would have used LPG. Since then I really rate diesel cars and would not like to go back to petrol. I now run my own car and claim mileage so I am out of the company car scheme. Much better all round in terms of money and personal tax, no what fuel you use. Best to all. Concrete

LPG - Ethan Edwards

Derv used to be cheaper than Petrol years ago but thats not the case now. If it's of any assistance. I switched from Turbo Diesel to LPG myself.

My colleague runs a 2007 manual 1.4 Fiesta TDCI and my 2010 1.6 auto N Note (LPG) pound per mile is cheaper to run though admittedly not by much.

It's best application is if you own a thirsty petrol car and don't want to lose it and run a motorised diesel skateboard instead. It makes running a larger engined petrol car (under the right circumstances) a cheap proposition.

LPG - Bobbin Threadbare

It's best application is if you own a thirsty petrol car and don't want to lose it and run a motorised diesel skateboard instead. It makes running a larger engined petrol car (under the right circumstances) a cheap proposition.

Indeed. Which I think was the point of this Jaguar; what more thirsty petrol engine can you get than a big Jaguar from the 80s?! He'd attempted to make it viable to commute in, and there's a number of places to get LPG around here.

LPG - dieseldogg

Hmmmm,

I know a local farmer, he runs two LPG cars, the first was a dual fuel Vectra, the second is a lovely big Honda with a cracking petrol LPG'd engine.

He does not use a filling station cos he got a gadget to fill offen the bulk LPG tank at (as it was then ) about 20p per litre.

Plus he got the VAT back.

flipping farmers (I'm jealous is all)