Lpg for my Range Rover? advice please

Eggonface · Post by **Eggonface** » Thu Nov 15, 2007 3:30 pm

Ok I have a P38 4.6 hse Rangie (p reg) and i cant afford the fuel consumption anymore because my commute has gone up from 15 miles a day to 55...

I want to LPG it rather than buy something more economical cus it's a great drive and tows my huge car trailer really well...

basically i can spend up to 1500 on the conversion but would prefer to spend less than 1000 on it if poss, what sort of system should i go for and where is a good place to buy it, I am quite capable of installing it myself as long as i have some sort of guide as i am a mechanic but not familiar with lpg systems..

I am aware that there are 2 main types of system and i have been told that the rangerovers dont much like the draw through systems, can anyone confirm this?
Also I get about 20mpg on a run and about 14 round town/hard driving.. what sort of mpg could i expect with lpg...

ChrisJC · Post by **ChrisJC** » Thu Nov 15, 2007 4:04 pm

For a P38 you really need an LPG injection system that fools the existing ECU into thinking that it's running on petrol. I don't think you can go for the crude 'mixer' type systems that work OK on the old 3.5 flapper engines.

I think the reason for this is the difficulty in stopping the existing ECU putting the petrol in but keeping it doing the sparking and all the other stuff that it does.........

£1K probably won't get you a new system.
£1500 might.

Chris.

kiwicar · Post by **kiwicar** » Thu Nov 15, 2007 5:20 pm

From my experience you can expect to see 13 to 14 to the gallon of gas, see a big reduction in performance and you need to replace spark plugs and leads about every 6 to 8k miles and need to do about 15% of your miles on petrol (now at 13 to the gallon) if the engine is over 60K miles old then it will need a top end rebuild in 30k of starting to use gas.
That 1500 is going to take a long time to pay back (mine never did in 80K miles infact it owed me £900 after an initial spend of 1400+vat) and it reduced the resale value of the car. If you are getting 20 to a gallon then I would spend it on a GKN overdrive and get it to 23-24 to a gallon on petrol, you will keep the power and your load space. If that is not enough then I would Diesel it and run it on chip fat

!
Mike

Eggonface · Post by **Eggonface** » Thu Nov 15, 2007 10:04 pm

yeah i thought that would be the case chris.. i was banking on getting a sequential injection system..

kiwicar, you seem to be one of the few taht have been dissapointed with lpg, what system did you use and in what car so i can try not to repeat your mistake!

diamond dave · Post by **diamond dave** » Fri Nov 16, 2007 12:45 am

Can't you sill mount the tanks like the Disco's ?

kiwicar · Post by **kiwicar** » Fri Nov 16, 2007 11:30 am

The set up I had was on a 3.9 RR (K plate vogue SE), the set up was a single Mixer put on the inlet to the plenum, built by the local "expert".
it went through three iterations of mixer and vaporiser to try find a set up that did not lean out over 4500 revs. It backfired if you opened the throttle to fast, the main reason I believe was the ignition was too far advanced on gas for the closing pointof the cam and with the mixer where it was the vac advance pulled in even more ignition advance and .... bang! However if you tried to use less static advance it burt the exhaust valves.
I think you will need as a minimum LPG injection, If you can get a high pressure system then all the better but I don't know if anyone makes a system commercially, you will need alot of CR.... I have stuck this in other posts though.
I would think very carfully about LPG, it does not save money in the way 50p a litre makes you think. The rover engine was never designed to run on the stuff so it hits your incidental maintenence bill hard and particullaly your cylinder head area.
If you have £1500 to spend on the car then think how much petrol that will buy you before you give it to some monkey touting LPG kits, wish I had.
My sister had an LPG kit on a honda civic, first engine converted at 23K top end rebuild at 45k second top end rebuild at 68K (burnt out exhausts each time), new engine as the whole thing was KNKD at 85k next engine lasted to 65k and that engine was a total rebuild at 63K (my sister commuted from Axminster to West Drayton three times a week). This was an injection set up and meant to be the best.
I think you can get it to work, I just think you need to forget dual fuel and spend 75 to 80 years developing it, the way they did with petrol engines (remember an A series bought in the eighties would have struggled to do 85 k before a rebuild!)

Mike

Eggonface · Post by **Eggonface** » Fri Nov 16, 2007 12:25 pm

Ok thanks for that, I shall heed your words

If i go for it i shall be getting a 'toroidial' (sp) tank which fits in the spare wheel well a design feature that classic rangies lack but P38's have a well big enough for an 18" rim with a high profile MT tyre on it... which is handy!

I wouldnt entertain either of the other systems as I need the boot space for my 2 dogs and I occasionally go offroad in it so Underslung tanks would worry me especially when wading or cresting ridges...

£1500 of petrol would only get me 6000 miles at current prices which is less than 6 months use, nearer 5 really, so £1500 of gas should get roud about 11000 miles, and given how easy top end rebuilds are on rover V8's chucking a set of valves in there every couple of years dosn't worry me much as it's less than a weekends work, I really dont see how it can affect the bottom end at all..

Views?

diamond dave · Post by **diamond dave** » Fri Nov 16, 2007 2:01 pm

On reading what Kiwi said, reminded of the exhaust valve problem.

Years ago we had the contract for a fleet of Sherpa vans ( "o" series engines ) that ran on LPG.
They were fine for around 60-70k ( 6 months running), then they started to burn exhaust valves.
After many rebuilds, Rover group came up with sodium filled valves & hardened valve seats to combat this problem, as they said the valves will run cooler.

Always wondered why they replaced the fleet with diesels after that

kiwicar · Post by **kiwicar** » Fri Nov 16, 2007 3:22 pm

you seem to have missed out the much reduced MPG on gas, I would recon you will get about 7800 miles on gas for the same cost as 600 miles on petrol.
LPG 50p/litre and 13 to the gallon as opposed to 20.
Mike

softdash3.9 · Post by **softdash3.9** » Sat Nov 17, 2007 10:09 pm

Bought my sequential injection kit from Tinleytech @ 3 years ago (£1200) and fitted it myself on my 3.9 classic. (tank size make a big difference on price)

on petrol she does @ 12/3 round the doors and @17 on a run

LPG is similar is 12 round the doors, 15/6 on a run

done @ 20k miles since converted, no valve issues but plenty of others

Eggonface · Post by **Eggonface** » Sat Nov 17, 2007 10:13 pm

Sounds good!

I shall give tinleytech a bell!

dit you find install and tuning straightforward?

(i take it youre in favour of the whole thing?)

badger · Post by **badger** » Sat Nov 17, 2007 11:06 pm

P38 engine management needs an SGI gas system, end of.
I'd recommend the OMVL Dream 21-N system with a 90ltr torroidal tank in the boot. I've installed more of these systems on P38's than I care to think about, with no issues at all.
The parts ought to be buyable for around £1100.

softdash3.9 · Post by **softdash3.9** » Sun Nov 18, 2007 6:23 pm

Eggonface wrote:Sounds good!

I shall give tinleytech a bell!

dit you find install and tuning straightforward?

(i take it youre in favour of the whole thing?)

Took a while to plan and execute the installation, gas pipe routing and wiring harness, had to take inlet manifold off to drill and tap for stubs.

Tuned it, Tinley tech supplied the software and lead on load, but I decided to buy a copy and lead at additional cost. So I could modify it if parameters changed.

Did find them very helpful, and they certified it for me, once installed (for a small additinonal cost)

My system is a Bigas, and have had no problems, but do research what systems are available, it is a big investment! there maybe better systems now, and Badger knows what he's on about, had several conversations with him, top bloke!

Eggonface · Post by **Eggonface** » Sat Dec 01, 2007 11:58 am

yup thanks for that had a chat with tinley tech and i think i'll be making a purchase from them in the next month....

Nice guys and very helpfull, top tip softdash!