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Discussion Starter #1
Hi
Looking for some information regarding LPG, thinking of having it fitted to my 1978 Silver Shadow can anybody who has got it fitted give me the plus's and minus
as to performance and long term effects on the engine, I'm doing about 6,000 per year and trying to work out whether it's cost effective.
Thanks Roger
 

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first you need to answer to yourself how often and how many miles you want to make it yearly. If is under 15K dont even think about it.
But anyway I think is just weird to put to such a majestic cars LPG, or even replace for diesel.
Valuability of this car will really drop down for future and if for sure many LPG positiv people will tell you it has no affect on engine, I am in totally opposite side. Even today 5% of ethanol in normal gasoline is making fuel too dry for our ventiles, LPG is much much dryer even with added lubricants.
Dont destroy such e nice engine please
 

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There's a chap here from Ireland who has a lot of experience with LPG and loves it and he's probably your man to speak to.

Personally, I hate it. And the thought of running a RR on it, for me, is like running a Ferrari on remould tyres. I had a bells and whistles sequential system on a Jeep commander 5.7 Hemi and I ultimately had it removed because it never produced the same performance as petrol and, in the long run, when every cost is taken into account, the saving was not all that significant. When these engines were designed, the engineers didn't spend one second considering it to run on anything other than petrol. For this reason, I don't believe you will ever get the same performance.

Notwithstanding the fact you have to sacrifice a load of boot space with a very heavy tank that you'll get very few miles from.

It's also a declining market because there are less and less vehicles around that offer themselves as typical candidates for conversions. The big V8 engined 4x4's like Jeeps and Range Rovers have been superseded by big diesels that perform good enough, or even better and whist there are one or two big petrol V8 4x4's still made, they are very low production niche vehicles like the Range Rover SVR or Jeep SRT - what I'm saying is, there are less and less conversions being done, less LPG cars on the road and the result of this is the number of places to buy it are contracting - so you often have to make detours to buy it.

This is what I heard anyway - and also anecdotally, when I was running the Jeep on LPG I regularly pulled into service stations to find the LPG pump out of action.

I think also you need to be doing more miles than 6000 to justify financially.

Anyway, just my personal opinion. Others may have a strong argument for doing it!
 

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LPG will only make about 80% of the power that gasoline (petrol) will make in heat so less power.
Runs very poor at low temperatures. Will not vaporize (vapourise) from liquid to a gas fast enough.
At very low temperature -40c will stay liquid. So you will need a block heat to help on very cold day.
To help with starting. LPG will run on engine with compression ratio 5:1 through to 20:1 very best is 14:1
Rolls is around 8:1 or 9:1 I would guess. 6000 miles seams a little low for the cost and limited
availability. Do you need fuel system inspection in England
 

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Even though I have no experience of LPG motors and will never have, I agree with the comments made so far.
Apart from the cost of the equipment you have to add on the amount of depreciation of the Shadow. I think most Rolls Royce enthusiasts would not even think about buying a converted car.
If you were going on a long journey it would need some planning to know where you could get LPG. I can see these will get fewer as they make way for electric car charging points.
Having less power on LPG than it already has and that's not a huge amount, would not be beneficial in any way at all.
Its a no from me as I cannot see any advantages at all, but like I said, I have no knowledge of LPG powered car engines.

Jake.
 

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Simple maths dictate a big NO if your only travelling around 100 miles per week - Cost of fitting £2000 - average saving per week on fuel will be £20 providing your getting over 12 mpg at the moment,if you think you will gain more saving on petrol your deluded - Time to recover fitting cost based on fuel saving is 2 years so savings will only begin in year three providing the unit is reliable and you dont have any leaks. Loss of power is also a factor and you will only manage a small hand luggage bag in the boot - Ive had LPG cars with big engines and to be honest its not a saving unless your keeping the car for 10 years plus
 

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Discussion Starter #7
Hi All
Thank's to all that have replied to my question, I was sitting on the fence about doing this conversion, but I have now fallen off.............on the side of not doing it
Thanks again for input.

Roger
 

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I am a bit late replying to your thoughts on LPG ,I have it on a spirit 1984 and I have done About 12,000 miles on LPG.
I don't find any noticeable difference in power,the car runs smoother on LPG than petrol.
I fitted LPG on a Bentley eight in 1988 and drove it for 25,000 miles on LPG without any problems
My Bentley was doing 18 mpg on petrol and 16 on LPG ( I FITTED A 2.28 DIFF ) the high miles was due to the diff ratio @ 1000 rpm with the standard diff =26 mph and with the 2.28 1000 rpm = 35 mph.
I have it on my Spirit now which is a 1984 and it is doing 15 mpg on petrol and 12 on gas.
70% of my driving is on motorway's.
The price to fit a unit in Ireland is 1400€ or 1150£
LPG is .70c or petrol is 138c
I have retired now and I am doing 6000 a year I am going to change the Rolls for a B 8 which I prefer,I don't know if it is worth putting LPG on the new car.tke pay back time would be just over a year.
I would not consider fitting LPG if I had to pay 2000£ (2400€)
 

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I have a 1975 Jaguar XJ5.3C that was converted to run on LPG and the first thing I did was convert it back to run on fuel. It took some effort because the PO ripped everything out (fuel rail, computer, wiring, tanks etc).
Why? Simple reason is that if I run out of fuel, I want to be able to walk to the petrol station and bring a Jerry can back.
 

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Discussion Starter #10
I am a bit late replying to your thoughts on LPG ,I have it on a spirit 1984 and I have done About 12,000 miles on LPG.
I don't find any noticeable difference in power,the car runs smoother on LPG than petrol.
I fitted LPG on a Bentley eight in 1988 and drove it for 25,000 miles on LPG without any problems
My Bentley was doing 18 mpg on petrol and 16 on LPG ( I FITTED A 2.28 DIFF ) the high miles was due to the diff ratio @ 1000 rpm with the standard diff =26 mph and with the 2.28 1000 rpm = 35 mph.
I have it on my Spirit now which is a 1984 and it is doing 15 mpg on petrol and 12 on gas.
70% of my driving is on motorway's.
The price to fit a unit in Ireland is 1400€ or 1150£
LPG is .70c or petrol is 138c
I have retired now and I am doing 6000 a year I am going to change the Rolls for a B 8 which I prefer,I don't know if it is worth putting LPG on the new car.tke pay back time would be just over a year.
I would not consider fitting LPG if I had to pay 2000£ (2400€)
Kevin. Thanks for replying, as they say better late than never I decided the mileage I do and the cost involved wasn't worth it.
 

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does anyone have any recommendations for someone to do a LPG conversion on a bentley turbo r 1989 i am in birmingham (midlands)
Seems foolish as i am not allowed to do 160mph anyway to worry about a little power loss, and you can always use petrol anyway if you need that extra bit you will never notice anyway
And 8 mpg is immoral (cool but immoral) when we can change it
And of course its going to be £6500 per year extra in birmingham for the clean air thing so with lpg i wont need to pay that

any help or history of experience with your own would be apprecciated
 
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