Topic: LPG, is it worth it? (Read 9667 times)

Andyp · « **on:** May 22, 2019, 09:38:23 PM »

I've had a 2001 V8 for nearly four years which was LPG converted before I got it. Over that period I added 80,000 miles. It may be the end of the road for this now at 205k with low oil pressure and tapping noises. I'd always thought that a good quality, well fitted conversion would be fine with any engine but before I buy another I'd like to get opinions from others with experience of LPG on different engines. As I do 20k a year I don't think a diesel Jeep is financially viable at under 30mpg so if I go back to the dark pump it will probably be something like a Kia Sorento or Hyundai Santa Fe (35 and 38mpg respectively). This means my options, as far as Jeeps are concerned are: WG 4 litre or 4.7, WH 5.7 or either diesel if there's a way to sneak mpg into the mid 30s. What are experiences of the three options on LPG? Does anyone have experience of chipped diesels that actually get the claimed economy increases? I look forward to a lively discussion!

Dutch · « **Reply #1 on:** May 23, 2019, 10:01:31 AM »

Andy,

Over the years these 'lively'discussions have been had.

Economy, single point/multi point, lube systems to prevent the valves on the 4.7 burning up ....... etcetera.

Try a forum search 'LPG' there's 29 pages of it - not all relevant but a lot are.

what did your last slave die of ......

Hillbilly · « **Reply #2 on:** May 23, 2019, 12:08:19 PM »

Hi, Andy. I can only speak from personal experience. I'm on my 3rd LPG 4ltr. The current one is an 03 WJ with a multipoint system which I've had for seven years. It has a 100ltr donut tank which fills 80 ltrs from empty. Depending on conditions, ie. urban or motorway it will cover between 270 and 300 miles. Do the maths with LPG at 57p-65p per litre I think it's pretty economical for a 4 ltr shed.

johnnyboy · « **Reply #3 on:** May 23, 2019, 05:17:21 PM »

Having done a bit of arithmetic with your figures to make them more "old school", I make that 15-17 miles per gallon.

At 60p / litre 10,000 miles would cost £1,600 - £1,780

With Petrol at £1.30 / litre that would come to £3,470 - £3,850

ie. a saving of between £1,870 and £2,070 over the 10,000 miles.

One niggle though: my old 4.2 litre CJ does a solid 20mpg on petrol (22/23 on a good day...), so I would have thought a nice 4.0l injection would have done more.... Do I remember reading that a litre of petrol has more energy than a litre of LPG and will do an extra 20% mpg?

If we say 20/23mpg on petrol, the savings halve so over 10.000 miles come down to £979 - £1.170

- which is not so good, but still viable[size=78%]?[/size]

Andyp · « **Reply #4 on:** May 23, 2019, 07:29:32 PM »

I've spent bit of time going through the search but nothing definitive really. My question relates more to longevity of the 3 engines when run on LPG with a good conversion and flashlube. The financial case, in terms of at the pump costs, is a no-brainer as LPG is less than 60p a litre round here. However, there are the niggling voices that keep telling the LPG is what hastened the issues I've had and I'd rather not put money into a vehicle that could be big trouble in as little as 2 years time. It seems that most people have been Ok for a while but then had issues on the 4.7 so I was really trying to find out if the 5.7 or 4.0 were better for LPG.

There's then the question of what mpg a chipped 2.7 or 3.0 would do...

Brynjaminjones · « **Reply #5 on:** May 24, 2019, 10:17:57 AM »

I have heard that the 4.7 can have valve issues on LPG, but I think it's somewhat prone to similar problems even on petrol. I have a feeling the 4.7 (and related 3.7) might actually be on the "black-list" provided by one of the LPG kit manufacturers for that reason.

We have a 4.0 on LPG and I don't think I've known anybody have an LPG-related failure with that engine.
We also have an old AMC 5360/5.9 on LPG which has just had the heads off. Interestingly, there was no LPG-related wear at all.
Neither of these have ever had flashlube.

JamesH · « **Reply #6 on:** May 24, 2019, 11:17:59 AM »

The 4.0 is the perfect for LPG, never gets wear from it. The 4.7 seems to be a bit fragile and there was a period a few years ago when there were several on this forum having trouble with them.
I don’t know about the 5.7 but in theory if it can use LPG and still close down valves for more efficient running like it does on petrol then it could be really good economy.

Andyp · « **Reply #7 on:** May 24, 2019, 11:58:17 AM »

Yeah, the MDS was definitely a concern. I could live with a 4.0 but I'd rather have a V8 if possible!

ChrisS · « **Reply #8 on:** May 30, 2019, 05:18:02 PM »

Converted our 5.7 to LPG shortly after getting it. Went for one of the most expensive systems on the market at the time. Conversion was £2500. Sadly, given we've still only done 15k miles since getting it back in 2011 it STILL hasn't quite broken even....

But FWIW, I've kept a spreadsheet since day 1. On our mostly short trips, mpg was averaged out at 13.7, cost-equivalent mpg works out at 25. Still pretty shocking, but given 99% of our use is on trip[s under 10 miles, not all that surprised. When we do ever go further than the local shops, it usually does 20mpg on petrol. It did 22 the day we bought it and given a steady motorway run, will still do the same.

No issues with MDS.

Was told it wasn't necessary, but I had the 'flashlube' add-on fitted too.

In unrelated news, was actually discussing with the missus when we should sell the old girl. December 2006 Overland 5.7, approx 95k on the clock (haven't looked recently). Offers??

wildwood · « **Reply #9 on:** May 31, 2019, 02:50:06 PM »

Had one on the YJ until it became a trailer queen then there seemed no point......enjoyed filling up for cheap for 5 years ....

Reduced space on the YJ as I went for the biggest tank possible..... Only when I took out the tank did I realise how heavy it was.....

Sold it to a gent on here.....think he still has the system.....complete with instructions and pre drilled manifold.....l

LPG around me has closed down so it's a 15 mile drive so not worth it.

Andyp · « **Reply #10 on:** June 01, 2019, 12:11:08 PM »

Quote from: ChrisS on May 30, 2019, 05:18:02 PM

Converted our 5.7 to LPG shortly after getting it. Went for one of the most expensive systems on the market at the time. Conversion was £2500. Sadly, given we've still only done 15k miles since getting it back in 2011 it STILL hasn't quite broken even....

But FWIW, I've kept a spreadsheet since day 1. On our mostly short trips, mpg was averaged out at 13.7, cost-equivalent mpg works out at 25. Still pretty shocking, but given 99% of our use is on trip[s under 10 miles, not all that surprised. When we do ever go further than the local shops, it usually does 20mpg on petrol. It did 22 the day we bought it and given a steady motorway run, will still do the same.

No issues with MDS.

Was told it wasn't necessary, but I had the 'flashlube' add-on fitted too.

In unrelated news, was actually discussing with the missus when we should sell the old girl. December 2006 Overland 5.7, approx 95k on the clock (haven't looked recently). Offers??

PM sent.

Andyp · « **Reply #11 on:** June 02, 2019, 03:51:32 PM »

As I suspected a good 5.7 is out of my budget. It sounds like all straight sixes will run LPG so it's whether I run the risk of another V8 or accept I have to have a 4 litre. Would multipoint valve ever be a better option that at the throttle body like I had before?

wildwood · « **Reply #12 on:** June 02, 2019, 05:19:12 PM »

Always,...... for many reason......go multipoint.....

Andyp · « **Reply #13 on:** June 02, 2019, 06:11:55 PM »

I meant multipoint valve saver, but missed some of the words! I wouldn't entertain a single point LPG system after the one I had on a Ford Explorer (converted before I got it, I hasten to add) kept backfiring and destroyed the air filter housing.

Allante666 · « **Reply #14 on:** August 14, 2019, 07:46:59 PM »

I know this is a bit of an old topic but just to add my two penneth worth, My last 7 cars have all been LPG and all but one have been V8's (mainly american). I currently have an old 2002 WJ GC 4.7 HO which was converted before I had it. Ive done nearly 50k in it (its now pushing 140k)and its never missed a beat, still drives like it should.
In all those cars Ive only ever had one with valve wear and that was a 2.5 litre Subaru which fortunately was real easy to get to and adjust the clearances.
I honestly wouldnt have anything else. Mine does a lot of short journeys around town and works out at around 24 pence per mile. We also have a 4.8 BMW V8 X5 on LPG and that worked out to 22 pence per mile.
Wife has a 3.7 V6 Cherokee which is petrol but will probably have that converted if we can find a combination fuel/LPG tank to go underneath. Anybody got one kicking around?

Andyp · « **Reply #15 on:** August 16, 2019, 07:06:18 PM »

There are a couple on Ebay that don't have the tank in the boot. Depending where you are in Lincolnshire you may be able to view one to see the setup or see where they were converted to get an idea of who can supply a split tank?

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F113834975472

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F193049734777

johnnyboy · « **Reply #16 on:** August 18, 2019, 08:12:09 PM »

Anybody recommend a suitable (multi point...) setup for a 4.2 CJ7? And where should I get one from?

Dave69 · « **Reply #17 on:** August 25, 2019, 10:37:41 AM »

to be fair you will get away with a single point system on a 4.2 especially if its still uses the carb. Multipoint only gains if you have fuel a fuel injection system like the 4.0ltr or have the head conversion and control system

Dave69 · « **Reply #18 on:** August 25, 2019, 10:38:57 AM »

considering ripping out the single point injection system on my jeep, only time it failed is when it had no gas in the tank.

wildwood · « **Reply #19 on:** August 25, 2019, 11:28:04 AM »

Going V8 then Dave?

Ooooer pics needed

Dave69 · « **Reply #20 on:** August 28, 2019, 09:51:47 PM »

will be, once i've found time to do all the other little jobs first. Just work and no time at the moment. The 2.5" OME springs have fantastic flex and coupled with 35s the jeep looks just at the right height.

have an old mopar 360 waiting to be fitted, just need to fork out the 750$ for the adaptor plate to allow the installation of the turbo 400. that might be next year as awaiting outcome of current plans which may involve a relocation so a realistic target is get jeep mobile first.

So yes LPG will be going

sorry to hijack thread

@jonnyboy my LPG might be up for sale, not sure value but will consist of two tanks and all stuff required to make it work. sensible offers will be considered

wildwood · « **Reply #21 on:** August 29, 2019, 10:36:42 AM »

Sold my multipoint YJ system to UK Jeeper for £250..... If that's a help.... They don't fetch much as people don't know how to fit em at home.....

Mopar 360 sounds like a great plan.....

Dave69 · « **Reply #22 on:** August 29, 2019, 11:37:40 AM »

Single point is even easier. Worst thing is I did a better job than the approved guy who installed it previous to my ownership.

Author Topic: LPG, is it worth it? (Read 9667 times)