To LPG or to not LPG

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Sonnycbr

Active Member
Posts
131
Location
Sunderland
Hi .all, I've owned a very nice P38 4.6L Vogue for about a year now and we are very happy together. It currently has about 70000 miles on it and I'm considering having an LPG conversion done on it to save a few bob. I had a bad experience a few years ago when I had an X Trail converted and the engine was fried inside 2 years.
Has anybody on here had a P38 converted to gas, and if so how did it go? Also, can anyone recommend a good garage in the North East to do the job? I think I paid about £1200 for my last conversion, what is the rough price these days?
Thanks for reading, and any help/advice will be very welcome.
 
My last one was a 4.6HSE converted to LPG.
I put 60k miles on it and only at the end did the LPG cause me any problems (float-valve sensor).
I think there is a huge element of "luck" with LPG on a P38. LPG may run a bit hotter and cause block cracking and liner slippage, but if the car already has 60K miles on it its unlikely to pop ( if they are going to, they usually go before 60K miles).
The LPG/Petrol cost ratio is nowhere near as LPG friendly as it used to be. A decent LPG install may cost you over a grand and that takes a long time to payback unless you are a high-miler.
As they say...."You pays yer money and you takes yer chance".
Good luck!
 
I'm not at all keen and am convinced many block problems are caused by hokey lpg installations. It's simply for £1200 that leaves about £300 pound to provide a convincing fuel map.
Run a big v8 lean( under full throttle) you've got a big issue. These consume 14mpg cruising let alone under full throttle.
Thor engine management are quicker to react and are therefore generally better suited than gems. This is not to say gems is slower just designed not to react to every instant change.
This is not an endorsement of any lpg though if you want to be driving your p38 in another 60000 miles don't do it. I also feel most lpg products are cheap rubbish injectors, vaporizors, pipes even all will fail in five years. The original petrol systems are very durable and of high quality.
Jb
 
Check out thread newb question below "I was surprised to find how rare lpg p38s are" ! The survivors are on petrol.
 
Sonnycbr said:
Thank you so much for the replies. I think that on balance, I probably won't bother with the LPG, if it aint broke, why fix it?
Click to expand...

It'll be fine. Just make sure the cooling system is up to scratch. The biggest issue is will you get your money back? If you're not going to convert it yourself then £1500 is a lot of fuel, even at today's prices.
 
Just thought a bit more: £1500 / £1.20 a litre = 1,250 litres. That's about 300 gallons? 18 mpg gives about 5,000 maybe 5,500 miles of fuel. That's probably all you do in a year if your mileage is that low. LPG is about a half the price of petrol (although you need more of it so that'll offset whatever it really is above the half I assumed)? So it'd take 2 years to get your money back. 3 years to make it worthwhile. If your mileage is higher then obviously it'll pay itself off faster.
 
If I was going to covert I would go the the place just outside Thirsk, I think they run a BTCC car. But I wouldnt do it,
 
I have had an LPG converted:

2003 4.4 L322 - BRC Sequent 54 system, No problems
1993 3.9 Classic - Lovato Single Point, No problems aside from the second ignition amp failing
1996 4.0 SE P38 - Not sure on make, could have been Lovata or Romano, No problems although this was a single point system but had no issues with it
1998 4.6 HSE P38 - OMVL Dream XXI-NG HP, the current one, bought it and the LPG wasn't working, swapped a few pipes around and now she runs on LPG fine, although I think the filters could do with a change
1999 BMW 735 - OMVL Dream XXI-N, No issues
1999 BMW 740 - BRC Sequent 54, again no issues.....

I have never suffered overheating, cracked blocks, slipped liners, worn valves etc etc....just ensure you maintain the system and the car, and there should be no issues!
 
If you're keeping it long term and doing the miles, I think it can be worth it. Had my 4.6 converted (single point, 135 L tank) at 100k and 8 years old. It's now on 285k and 22 years old. I calculate that I've saved around £35k in fuel costs in that time and it feels good to know that the journeys I'm doing aren't costing an arm and a leg. I guess I get more use out of the vehicle because of that. Also having LPG was handy when my fuel pump packed up once - extra layer of fuel redundancy. But it all depends on your individual circumstances.
 
There are pros and cons of LPG, but for me, the biggest bugbear was how long it took to fill up, especially at the older pumps. You have to hold the button in on the garage fuel pump for flipping ages. On the motorway, it would take me over half an hour to catch up with a lorry I'd previously overtaken just before pulling off to refuel. You have to have it serviced every year which adds about £200 to the overall cost.

Col
 
If the cooling system is up to scratch and you use a good quality oil, then any engine in good nick is a candidate.

We have two D2 V8's on gas in the family, both have been reliable, both covered high mileages on gas.

My latest car, a 4.6 Rangie Vogue is on petrol, and not really enough space to fit a decent LPG vtank and keep the full-size petrol tank, which we prefer.

Peter
 
Simple answer from me :
DON'T :(
If you're contemplating conversion purely to save on fuel costs long term ...
Stick to the fuel the vehicle was designed to run on, but if you can't afford it buy something more economical.
 
Last edited:
There's no question LPG makes running the V8 bearable if doing the mileage. Jury is still out for me as to the long term effects of running LPG on the RV8. Mine got through 2 engines during the 85k miles i did despite totally renewing the cooling system when i got her & regular servicing of the LPG system(first replacement LR engine dropped a liner & the second top hat block cracked & regular HG failures). Never got to the bottom of why this was happening but suspect LPG wasn't helping as it could stress an already weak block design with the lean fuel mapping these run on.
 
I remember the first time I did hg on one the mass of rubbish "up top" with lpg was ridiculous. This one had 2 smaller vaporizers for each bank. Pipes and wires were like spaghetti. The lpg loom is about 5 foot long and cable tied in a bunch. It made jags v12 look simple! I think single point can have advantages in simplicity terms and I have known some reliable long lasting installations but they are rubbish power wise and can have backfires.possible only on pre Thor v8s though.
 
johnnyb70 said:
I remember the first time I did hg on one the mass of rubbish "up top" with lpg was ridiculous. This one had 2 smaller vaporizers for each bank. Pipes and wires were like spaghetti. The lpg loom is about 5 foot long and cable tied in a bunch. It made jags v12 look simple! I think single point can have advantages in simplicity terms and I have known some reliable long lasting installations but they are rubbish power wise and can have backfires.possible only on pre Thor v8s though.
Click to expand...

Driven a few GEMS on LPG now and power drop was not even noticeable. One had HG failure at about 110k miles but that seems standard for the 4.6 regardless of LPG. You're right though, all the extra crap on top doesn't help when doing the HG!
 
I've had two V8 Discos and a V8 Classic and two Mercs on lpg. Always kept the complete petrol tanks as up here there aren't that many filling stations and the price grew to be not much cheaper than petrol when you consider the lower mileage from LPG and I lost an awful lot of boot space
 
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