lpg vs. diesel

[poohbear]

OK, not wishing to start a debate here but -

Which will be cheaper to run fuel wise for a regular 5 mile commute - mostly through town and twice a week on dual carriageway, plus the odd journey to shops and out of town - a 1996 DSE manual or 99 HSE 4L V8 with multipoint lpg?

My guess is the diesel has it due to warm up time on petrol with the v8.

Dave

[Dave W]

From experience there will be very little in it in running costs, if anything the V8 on LPG will have a slight edge but that will depend on your local LPG suppliers and how aggressive they are on pricing. In some areas LPG suppliers tend to overprice the LPG, particularly if there's not much local competition. If you're in an area like that the sums may not add up for you.

I would spend some time looking at the local LPG stations and what they are charging compared to the cost of diesel.

The warm up time will probably give the V8 an advantage, the diesel will take MUCH longer to warm up, especially at low speeds/around town.

[poohbear]

Thanks Dave,

any chance the MPG of either would be comparable to a 110 200Tdi, which is currently around 24'ish? I'm desperately trying to convince myself that I can make the figures stack up!

At this rate I might be sticking with the Defender and running it on veg oil!

Dave.

[Dave W]

I would have thought either would be better than a 110 200TDi. Even at 15MPG on LPG it would still be cheaper to run than a 200TDi getting 24MPG.

The P38 Range Rover will get better MPG anyway than a 110 with the same engine, especially over 50MPH. The P38 has something called "aerodynamics" whereas the 110 treats air with contempt and just barges it out of the way.

I get up to 22MPG in my 4 litre V8 P38 auto on a motorway run but combined it drops to around 18MPG or 16MPG if I really try hard In very rough figures for LPG knock 2MPG off the petrol MPG as, even with a sophisticated LPG system they all seem to lose around that much. Double it for the comparative diesel cost. On LPG in a manual P38 you're probably looking at the equivalent of around 32MPG on diesel, cost wise, 36MPG on a motorway run.

The same engine and gearbox in a Discovery gave me 16-18MPG, the same engine and gearbox in a 90 gave me 12-16MPG, air resistance is a bitch.

On a DSE I'd expect to get somewhere between 30MPG to 35MPG, as I said before, the cost of LPG locally relative to the cost of diesel can make the difference in cost. Having said that the V8 will be MUCH nicer to drive

[poohbear]

OK - final dumb question: I'm assuming all lpg converted engines have to warm up on their native fuel before being able to run on the lpg?

[duncmc]

My RRC is giving me the equivalent of 28mpg on diesel when I take into account the cost of diesel and LPG locally. Its an auto, and is less aero than a P38. I also get warm air coming out of the vents after about 1.5miles.

As Dave says much nicer to drive than a diesel too.

[Bowie69]

OK - final dumb question: I'm assuming all lpg converted engines have to warm up on their native fuel before being able to run on the lpg?

No not all, some are dumb, and have no ECU, and can run without warming up on petrol first, my RRC being a good example, I didnt use petrol really ever, even down to -10C.

[p76rangie]

Mine is a smart closed loop system and does not warm up on petrol

[Cynic-al]

Mine starts on petrol but as soon as you take the engine over 1000rpm it switches to gas and runs fine. I know people who have no petrol in their engines at all. Biggest problem I find with LPG systems from people who slag them is because they have never set them up properly or serviced them, they just assume it will work.

[zim]

For approximately 300 - 500 miles a month you'll do just go for the V8. Not sure which will work out more, but the difference won't be a lot. However you'll prefer driving the V8.

I've done about 40 - 50k in my 4.6v8 on lpg and no real complaints.

G

[geoflse]

OK - final dumb question: I'm assuming all lpg converted engines have to warm up on their native fuel before being able to run on the lpg?

We ran a 110 fitted with a 4.6 RPi engine and didn't even carry petrol. In fact the only petrol tank in it was from a speed boat!!

My P38 4.0 SE starts and runs ok on LPG only, however, it does start easier on petrol and doesn't crank for quite as long as it does starting on gas.

Comparing LPG and Diesel, my Wife has a Freelander td4, 2001 (manual), and I feel that my P38, (4.0 auto) on LPG seems to be a tad cheaper to run and it's definately nicer to drive!!

I used to have a P38 DSE and it was nice to drive, too. I didn't find it particularly sluggish. I did fit the cold start fix, which definately helps if you do short runs.

P38's are cheap as chips nowadays and a lot of car for the money.

Geoff

[poohbear]

Thanks gents - some interesting reading there!

Dave.

[poohbear]

Right, off to part-ex the 110 on Tuesday (hopefully!), option of either a '96 DSE or a '99 HSE V8 on LPG - now the V8 has a very good service history with a price to match and the DSE has less evidence of service history but will be a straight swap for the 110. So performance aside, which will prove to be the most hassle free motor?

Answers on a postcard to......

But in all seriousness, is there anything in particular I should be looking at when giving them both the once over. One of the advertising photos of the DSE dash shows a yellow/amber warning light which is a picture of the vehicle over an arrow pointing upwards, is this anything to worry about?

Dave.

[Dave W]

The main thing with any P38 is making sure everything electrical works.

Make sure you put it into low box and back again, (It's a servo motor system and can get stuck)

Check the air con is charged and working, Cycle it through all suspension heights to check the height sensors.

If it has electric seats make sure they are fully operational.

On the V8, listen for any rattles from the cat.

Check all the washers and wipers work - rear as well as front/headlamp (the rear washer pipe often gets crimped and stops it working - a real PITA to find and fix).

Check the carpet, in the front footwell around the tunnel, for damp. The O rings on the heater deteriorate and coolant leaks down the side of the tunnel into the footwells.

There used to be a really good Range Rover site with decent buyers guide on it - can't find it now though, perhaps someone else can find it and post a link.

[task]

This site?

http://www.mez.co.uk/p38.html

[Dave W]

This site?

http://www.mez.co.uk/p38.html

That's the one

[Bowie69]

This is also good: http://www.rangerovers.net/

[Tanuki]

Make sure the LPG setup is a proper one - individual LPG-injectors, closed-loop control and separate ECU.

Anything involving vapourisers-and-venturis is best avoided - they're the equivalent of a rather-poor 1960s-vintage carburettor, with all the starting/running/poor-efficiency problems that implies. I've seen a few exploded airboxes on such systems, and one case where the fuelling was so wrong it made the catalytic converter glow red.

--Tanuki

[Bowie69]

I've seen a few exploded airboxes on such systems, and one case where the fuelling was so wrong it made the catalytic converter glow red.

and so have I for sequential systems!

Draw through systems are great, simple to maintain and setup, get either wrong and you are in a world of pain. I believe though, that the P38 requires a sequential setup to work properly, something to do with the updated ECUs, though I will be happy to be proved wrong

[poohbear]

Thanks gentlemen - some great stuff there.

I'll let you know how I get on.

Dave.

[elbekko]

and so have I for sequential systems!

Draw through systems are great, simple to maintain and setup, get either wrong and you are in a world of pain. I believe though, that the P38 requires a sequential setup to work properly, something to do with the updated ECUs, though I will be happy to be proved wrong

I know a few that work really well with the regular single-point venturi setup.

Plus the GEMS can actually self-tune its spark map a little for the LPG.

[poohbear]

Well that was a wasted day......

Turned up to look at the DSE which would have been a straight swap for my Defender only to find that it was in bits - baring in mind I had been having a quite in depth email exchange regarding wanting to part-ex my defender - alarm bells getting primed and ready to go.

So asked about the LPG HSE from the same yard that I had had previous email correspondence about - "it's over at the gaffers house mate" - Alarm bells now getting well and truly warmed up.

So the HSE gets parked up on the street, seriously, it had one set of wheels in the road, so I tried to have a look round without getting run over. Engine is well hot, not just warm - Alarm bells now making a merry little tune in my head but I've driven 50 miles in the defender to get here so I might as well have a look. Front foot wells are damp around transmission tunnel, C/C display is showing the dreaded book with an exclamation mark and doesn't blow cold and the dash is telling me that non of the windows are set. on the plus side air suspension seems to work faultlessly.alarm bells now playing a merry little tune in the back of my mind.

Under the bonnet - sounds alright, maybe a slight misfire but starts, runs and revs freely. Pull the oil filler cap off and can't find any evidence of the wet black stuff, transmission dip stick similarly vague as to the location of lubricant, also found a random bit of emery paper in the engine bay?! Alarm bells now hammering out at full volume.

Needless to say - turned it off, returned the key and drove away in the Defender.

Oh, and having got back home I have realised there was no fan cowling.

Still I'm now one closer to the one I want.

Thanks to all who have given advice/info or just piped up - I feel I may be at the start of a very long journey. Anybody want to swap a P38 for a Defender?

Dave.

[nicks90]

stick with the defender - give the engine a good going over and run it on veg oil.

much much much cheaper to run than any p38 can ever hope to achieve!

we have just recently gone through the pain of choosing a new 4x4 for towing caravan, dog wagon, daily drive for the missus etc and I really wanted a p38.

even got her indoors to drive one - late model well over budget, but gives you an idea of what a 'good one' feels like - and she liked it!

So the search was on to find one in budget. We didnt find one. Every single p38 we looked at was a nail. Either had terrible electrical problems or had interstellar mileage with dubious history. It was a real shame, if we could have stretched to a couple more £k we could have had a nice one, but under £4k they are all sheds now. Well, at least the 10 we went to see were!

[poohbear]

I had planned to run the 110, as you suggest, on veg oil - but there was no way SWMBO would ever drive it. Compared to a 'proper' car the defender is way under spec safety wise for travelling about with three kids on board and I couldn't justify spending the time fixing it up.

As it is I found a 95 4.0 SE with 155k on the clock, service history to 153k, for a snip under 2k. It was fitted with a sequential lpg system in 2010 and having replaced the MAF and Lambda sensors is giving me around 18mpg.

Yes there are some niggles but I have a background in fixing brocken electrical 'stuff' so am not phased by the presence of numerous computers running things. Spare parts are plentiful and there is at least as much forum support for the P38 as there is the Defender.

I spent Friday working on a waterlogged site and it has towed everything the defender would have towed - 2 weeks in and I'm glad I made the change.

Dave.