Well I think I'm just going to do it!

From what I've heard if the LPG all goes horribly wrong, I'll need new hardened heads from JE, probably after 30-50k miles. this would cost maybe £3,000. In that time I'll have saved £4,000-£7,000 in fuel costs, IF I still have the car. The conversion costs around £1,550 plus VAT, this will be recovered within one year. One year warranty on the car, two years on the LPG conversion.

I think it's a no brainer, as fellow LPG owners will confirm, there's nothing like being able to enjoy a fantastic powerful engine whilst knowing that you're paying half(ish) price for the fuel! Range Rover-less at the moment - Pining!

It's not the hardened heads and valves that bother me it the engine light problem and the possible niggles that may happen and possible loss of power. You never here about a good conversion just the bad.

Good look to ya mate and please keep us informed as rather than risk mine I'm just gonna get a second car that the wife will use so the range is only for me at weekends! Hopefully once or if a conversion has been perfected I can sell the second car and still have money left to get the conversion.

Cheers

Bozmandb9,

I'm sure there are many excellent LPG conversions out there - however, having experienced LPG conversion on a previous 4Litre off-roader I had, I certainly wouldn't let a converter anywhere near my beloved Range Rover! All I'm saying is think really hard and do lots and lots of due diligence before taking the plunge. On my old vehicle (a Ford Explorer) I had a never ending chain of problems with the car after conversion, even when running on petrol. Prior to the conversion the car ran sweet as a nut and was a pleasure to drive, after conversion (which was a "premier" job costing nearly £3000) the car never ran well again, often stalling at innapropriate times (a nightmare in an automatic!) and sufferring loss of power and horrible gas smells. The theory sounded great, but in practice the whole thing was a nightmare that led to me having to sell the car - something I otherwise wouldn't have done as I loved the ol' wagon.

Just be careful!

If I'm following this thread correctly the OP is getting a gas conversion on an SC for £1500 ish

I'm on my second SC and did enquire about the gas conversion a couple of years ago and for a decent one it was £3k to £4k - so I'd be a bit worried about somebody doing it for half that now

My personal opinion is leave well alone as you may well ruin a good car and I doubt that it will make it any easier to sell on when the time comes just enjoy it as it is - even with AT tyres fitted I get 17.5 mpg average which given the price difference of petrol to diesel makes it pretty close in economy terms to a td6

Too late now anyway chaps, I'm hoping to pick it up tomorrow if it's completed.

The conversion place have done a couple of 4.2 supercharged. To be honest if they'd had problems with them, why would they want to do more? There are plenty of engines which convert easily, like the M62 4.4 engine, so if the Jaguar Supercharged was problematic, why would they offer to do it and have the headaches when it comes back?

I'm sure there were plenty of problems with the early conversions on the Supercharged 4.2. I've read of installations where there was no fuel return line, leading to poor running and engine lights on (which seems to be very common, but not where it's done properly), it's being fitted with a flashlube system, which may or may not protect the heads, if not then worst case scenario I'll get the hardened heads from JE after 30-50k miles.

Can't wait to pick it up now! Range Rover-less at the moment - Pining!

Well this is getting interesting now! Fingers crossed that it's all good. I'm just about to get the wife a fiat 500 for her to potter around in. Hopefully once a conversion kit has been successfully tested I'll sell that and get mine converted so really interested in your results.

You have to keep us informed.

Cheers

bozmandb9 wrote:

Too late now anyway chaps, I'm hoping to pick it up tomorrow if it's completed.

The conversion place have done a couple of 4.2 supercharged. To be honest if they'd had problems with them, why would they want to do more?

I was in JE on Friday last week and this came up in conversation. They mentioned they had done an early SC but it was problematic due to the hardened heads required.

As the SC are generally cheaper to buy than the TDV8s, I'd notionally put that saved money in the purchase towards petrol and leave as is (IMHO)

But, if we didn't try these things we wouldn't know for the future so please keep us informed and let us know if you have any issues. Discovery 4 HSE
1998 110 TUM HS FFR Hard Top XD WOLF
1982 Series 3 Hard Top

*Gone:L462 D5 HSE LUX, L663 Defender 110 HSE, Discovery 3 HSE, 2014MY Range Rover Sport 5.0 Supercharged AB Dynamic; L405 Exec Vogue SE 4.4, 5.0 Supercharged Autobiography, Defender TDCi XS CSW, Defender TD5 HT, Vogue SE TDV8, Vogue TD6, RRSport SC 4.2V8, Classic 3.9 Vogue Auto, Land Rover Series 3 SWB

There seem to be plenty of Jags and RRS s/c which are happily running on lpg, and they all have the same heads. To be honest if its all going to go wrong then the sooner the better, since if its within two years then its down to the conversion place to stump up for the new heads!

Will keep you all posted! Care not ready yet, hopefully Mon/Tues (hope they're not already having problems!  Range Rover-less at the moment - Pining!

sharpm wrote:

If I'm following this thread correctly the OP is getting a gas conversion on an SC for £1500 ish

I'm on my second SC and did enquire about the gas conversion a couple of years ago and for a decent one it was £3k to £4k - so I'd be a bit worried about somebody doing it for half that now

My personal opinion is leave well alone as you may well ruin a good car and I doubt that it will make it any easier to sell on when the time comes just enjoy it as it is - even with AT tyres fitted I get 17.5 mpg average which given the price difference of petrol to diesel makes it pretty close in economy terms to a td6

bozmandb9 wrote:

Fantastic economy, is that from the computer or manual calculations? If I can get that from lpg I'll have a 30 mpg s/c!

bozmandb9 wrote:

There seem to be plenty of Jags and RRS s/c which are happily running on lpg, and they all have the same heads. To be honest if its all going to go wrong then the sooner the better, since if its within two years then its down to the conversion place to stump up for the new heads!

Will keep you all posted! Care not ready yet, hopefully Mon/Tues (hope they're not already having problems!

Phil. wrote:

bozmandb9 wrote:

There seem to be plenty of Jags and RRS s/c which are happily running on lpg, and they all have the same heads. To be honest if its all going to go wrong then the sooner the better, since if its within two years then its down to the conversion place to stump up for the new heads!

Will keep you all posted! Care not ready yet, hopefully Mon/Tues (hope they're not already having problems!

It's not just about the heads, it's the set up that will cause most problems unless you are very lucky.

For some reason (probably software) the engine management on the 4.2 S/C RRS is different to the 4.2 S/C FFRR. Most of the RRS 4.2 S/C LPG conversions set up well. The FFRR 4.2 S/C seems to be more complex and it's very difficult to get a good balance between running on Petrol and LPG. It's often ok for one but not the other. This makes for all sorts of problems because a cold start is always on petrol and then it switches to LPG at a pre-set temperature. So in practice both set ups have to work and if one of them isn't working well then all sorts of running problems occur. The 4.2 S/C engine management software is also constantly adjusting itself, making a good set up even more difficult to achieve. You may get a good set up for a while and then it automatically adjusts and problems occur again, often different ones. If you have half the issues I did then you will be driving around with the yellow engine management light on or waiting for it to come on every time you start it.

If your LPG guys get problems setting up the system initially then you may consider asking them to remove it completely and immediately before it ruins the petrol operation. It will be a lot cheaper and less hassle than trying to make the LPG system work in the longer term.

I did exactly what you are doing now 2.5 years ago on a 55 plate MY2006 with 20k miles, so appreciate your reasoning and enthusiasm. Best of luck!

PS While I'm thinking about it. Due to the calorific value of LPG, when making use of the 400bhp 4.2 S/C, the LPG has to switch to petrol on high load and then back again to LPG. This change over point can also be a point that set up problems occur.

I don't know if mine had a fuel return line but it does seem to be the holy grail for the 4.2 S/C according to the LPG forums.

I read that post earlier. It's about the RRS and Jag XJ rather than the FFRR.

My understanding is that the need to switch to petrol when at full load is not due to which LPG injection system is fitted, it's due to the calorific value of LPG which can't provide the energy to achieve the required power at high loads.

Mine was fitted by JE and they were great throughout. Give them a call and ask about Phil's S/C conversion. They will remember, so will be able to answer your question about whether a fuel return line was fitted.

And let us know how yours is as soon as you get it! It will be great if someone has found a solution.

I haven't got my car yet, but I have found a very successful prior conversion to a 4.2 s/c FFRR. It's a guy on Pistonheads, I found one of his posts and e-mailed to enquire about his gas conversion and received the e-mail below:]


Thanks for the e-mail. I've done the best part of 70,000 miles in mine since the conversion and its not missed a beat. There are always people who say you shouldn't do this or that but to be honest I haven't had a moments trouble. There is no loss of performance on LPG and changeover on running out is seamless. The only real bug bear is the rising price of LPG. Two years ago it was down at 47p, now its over 80p and they reckon inflation is at 3%!! I've been thinking about changing it for a Bently GT or a Phantom, but to be honest its such a great car I'm going to keep it for another 12 months. I recently drove it down to Monaco as I have a boat down there and used the continental LPG adaptor so I had cheap fuel there and back.

I generally on average get 15 mpg either on petrol or LPG around town and 20 on a run. So I guess if you take into account the reduced price of LPG that equates to about 20 and 25 mpg.

Anyway hope your conversion goes well. Range Rover-less at the moment - Pining!