LPG CONVERSION PROS AND CONS QUESTIONS.

Discussion in 'Mech Tech' started by Poptop2, Jun 22, 2013.

  1. You don't have to be too cynical to agree with this. As soon as there's significant uptake of LPG, it'll be taxed to the max, I'm afraid.
     
  2. The best way, of course, of getting almost limitless amounts of energy to push your van along is to install a small nuclear reactor. I've never seen them in Halfords, but GSF is worth a try.

    You may have to get permission from someone to do this.
     
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  3. Someone I know said this to me many years ago. I'd suggested that his small fleet of diesel vans running 200,000 miles a year could save him a fortune by changing to LPG.
    10 years on, he's still working around the clock funding all the diesel he's burning LOL
     
  4. Moons

    Moons Moderator

    Been out today so late on the reply!

    Just for clarity, Vauxhall themselves claim 38mpg for combined cycle for a gen 2 1.8 Vectra, your claimed figure nearly matches their figure, despite the physics of the fuel sources, that's remarkable.

    I suspect there are two points where error is creeping in to the maths:

    If you do a lot if extra urban miles then the mpg improves, just as it would for petrol.
    If you don't factor in the petrol used to start most LPG conversions, and this runs the engine at its least efficient cycle (cold start up, short journeys before LPG kick in) then maybe the 20% -25% drop in efficiency is being cancelled out .

    So I'm guessing can someone confirm based on the figures listed if either vehicle only ever runs on LPG and LPG only?


    I'm trying to establish accurate and repeatable maths so that people can genuinely work out the point at which a conversion makes economic sense.
     
  5. Poptop2

    Poptop2 Moderator

    My problem is the initial cost hence the buying secondhand thoughts . The van will defo not do enough miles to justify a properly fitted new system job , no way!

    That is why i am asking questions on what to look for when buying s/h!
     
  6. Moons

    Moons Moderator

    This thread reminds me of the nutty one last year about the undertray pan things and tail sections for vans!!
     
  7. Birdy

    Birdy Not Child Friendly

    I'm beginning to not see the point of them. As previously mentioned by me I've seen LPG at stupid prices and it's bound to go up inline with unleaded which will soon make it totally pointless. An you get worse to the gallon with it and am l right in that it isn't great for sustained high speed cruising?? And in that I mean 60mph for hours on end?? I'm sure I read that. Someone correct me if that is wrong.
     
  8. Moons

    Moons Moderator

    Must confess mine was fine at sustained motorway speeds...it was urban driving it struggled with.
     
  9. Poptop2

    Poptop2 Moderator


    i am beginning to think the same re tax tbh!
     
  10. Are we talking about nuclear reactors, or LPG? Propane does burn hotter. Aircoolers don't really like hotness.
     
  11. Birdy

    Birdy Not Child Friendly

    It will happen. I'm not being cynical (I lie like a cheap rug) but considering its seen as a clean environmentally better fuel you would have thought it best that they keep the prow down in order to encourage more to retro fit it. However the price has jumped 90% in recent years and it will soon be no cheaper than unleaded. I predict in 4 years it will be priced the same as unleaded.
     
  12. Over the past 11 years, LPG has cost a consistent 60p-65p a ltr less than unleaded, this is the same throughout the EU.
    And over the past 11 years, people have talked about the tax benefit being abolished but it ain't happened.

    Yesterday I drove 170+ miles on the motorway using an lpg Vectra 1.8 estate enjoying the equivalent of 72 mpg. This car drives about 18,000 miles per year, all on LPG, and it doesn't take long to pay for the installation.

    The 18,000 miles average about 34mpg on gas, which is the equivalent of 66 mpg including local trips. That's a total cost of around £1700.

    On petrol (maybe 40 mpg average on petrol, probably a bit less) , the cost would have been around £1k more
     
  13. Moons

    Moons Moderator

    Bizarrely - I'm unsure (I say bizarrely as my replies in this thread sound very anti LPG - whereas I prefer to establish some facts which (with the exception of my esteemed co-forumers) seem in short supply - i.e. the web is littered with figures and confusing maths that the LPG industry has put out there).

    I had mine converted in 2002 and all those fears about an imminent tax hike were as true then as now. I think there is some significance in the grant system for 'green' cars being binned - I suspect though that that is a mixture of austerity and not being able to prove its business case.

    The biggest issue I can see is this, and I'd ask people to forget the financial aspect a moment:
    For one Gallon of Petrol a modern car will do 40mpg
    For one Gallon of LPG a modern car will do 32mpg
    For one gallon of Diesel a modern car will do 52mpg

    Me personal view is that with the exception of maybe Australia, no major manufacturer has made any efforts to improve the efficiency of LPG cars in their own right - all efficiency's are found by the petrol engine car being improved.

    As my earlier posting tries to establish - the two fuels have different characteristics - the more you optimise any machine for one fuel, I suspect this makes running it on something else a compromise. The LPG industry have it that their piggyback ECU's fix this - I still think this is incorrect due to an abject failure of this technology on my own car, and the simple fact that piggybacking any live telemetrics a cars ECU uses incurs error in to that system.

    So long term - petrol engines are getting smaller and turbo charged - with other technologies such as direct injection and improved catalysts improving performance and cleaning up the emmisions - Diesels are getting twin turbo chargers to get more bang for buck - neither of the above engine types would welcome a fuel that burns hotter.

    I think what I am basically saying is that LPG's 'business case' is purely down to financial incentives due to the tax break, whilst it does have environmental benefits there is seemingly little or no work being carried out in improving its actual efficiency.

    At the moment, its very well suited to older cars that have poor MPG anyway - you just need to be ever mindful that it is categorically NOT 50% the efficiency or running cost of a petrol car (btw this isn't just me saying this, the AA do too for example - http://www.theaa.com/motoring_advice/car-buyers-guide/cbg_fuel.html) and need to do the maths for when the install actually pays for itself - you can then factor in the 'unkown' element where the government might hike the tax, and, my main issue, that the technology itself is in the majority not fit for purpose, obviously with some exceptions like Mike!
     
  14. We had an LPG conversion on our 8.0 litre V10 Camper, simply because it only did 5 (yes 5!) to the gallon but it was hideously unreliable.
    Power was down when on LPG as was MPG at sustained cruising (4.2!!! :eek: ), we did around 40,000 miles in that bus half of which was on LPG.
    Availability is another issue, whilst GB has a few stations and France is well covered, there are virtually none in Germany, Spain or Italy, Switzerland use a completely different system as do the Scandinavians.
    If you do high (ish) miles and run a reasonably old car then it's MAYBE worth it.
    We get 60+ mpg from our diesel Audi A4's and diesel you can get anywhere!
     
  15.  
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  16. ONE YEAR LATER............................

    Made a computer diary note to re-visit this thread after a year to re-evaluate concerns about LPG conversions. The main ones were that running a vehicle wrecks engines and the government might cynically abolish the tax advantages of LPG shortly after incuring the expense of fitting it.

    Three things have happened to my lpg experience over the past 12 months

    1. The government has not altered the tax on lpg, in fact it hasn't during the 13 years I've been running it in different vehicles.

    2. Our car has been scrapped at 232000 miles because of the clutch, too uneconomic to repair. The engine still drove like new ;) We now have another lpg car

    3. Our approx 20k miles over the past 12 months have saved us around £1000 compared with running the same vehicles on petrol. That's £1000 towards the Bay fund :thumbsup:
     
    Last edited: Jul 2, 2014
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  17. And...best of all...you're no longer driving a Vauxhall :thumbsup:!
     
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  18. Poptop2

    Poptop2 Moderator

    I looked into it and decided against lpg on the bus has it was too expensive to fit taking into account the limited mileage I do each year in her. That said the new crewcab had lpg fitted back in the 80's and the failure of the gas system caused the engine to fail completely. I have no idea why, it is simply what I was told by the previous owner. it still has all the components in place to work in theory, but I shall be removing them.
     
  19. So far running my T25 on LPG has saved me £1800. Better than a kick in the nadgers.;)
     
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