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A6 4.2 Quattro on LPG?

Discussion in 'A6/S6/Allroad forum (C5 Chassis)' started by reggieroo, Aug 14, 2010.

  1. reggieroo

    reggieroo Member

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    While looking at A6 Avants last night I cam across a really nice fully loaded A6 4.2 Quattro. It had recaro leather, tv, dvd, sat nav well the list goes on. It also said it was 340bhp, is this correct?

    Anyway I was looking for a 2.5TDI 180bhp to begin with but when I came across this I thought Mmmmm LPG it & I will have a nice V8 with diesel economy & all that power.

    I looked at some figures online & it said that the 4.2 V8 gives a combined 21mpg so I figured take a few mpg off for the lower efficiency of LPG & double it as it's half price should give you equal to 36mpg. Isn't that about the same mpg as a 2.5TDI 180bhp?

    Anyone got one of these on LPG as it needs real ownership to truly confirm what it returns in real life?
     
  2. Herald

    Herald New Member

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    I have a 2004 4.2 allroad. I'd love to get 21mpg out of it. Mine does 15-16 around town and 19 on a run at 90-95mph or 23 at 70-75mph. I know as a write down every drop of fuel that goes through it and have 15000 miles or records. Would I have another one? You bet, it's a V8 and you forgive it everything when you hear it.
     
  3. Mudplugger

    Mudplugger Member

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    I'd advise you to do some very careful research into the life expectancy of valves & seats, without the lubrication effects of petrol in there.

    Many DIY (i.e. not original manufacturer) LPG converted cars tend to need expensive cylinder head work after 50,000-60,000 miles, and the cost of that far outweighs whatever you think you may save in fuel costs (even before factoring in the cost of the conversion).

    I was at one point considering a LPG-converted 2.7T Allroad, but no matter how hard I looked I couldn't find a single example of one that had covered a proper mileage (i.e. at least 100,000) after conversion on which to base a decision.

    I'm very happy with my 2.5 TDI Allroad :)
     
  4. reggieroo

    reggieroo Member

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    I too looked at several LPG converted 2.7t allroads but none looked any good so I bought a 2002 2.5TDI allroad a few months back & love it, especially now the bad weather is here. I also have a LPG V8 Range Rover classic that only runs on LPG & no problems what so ever with it on LPG for the last few years. I plan on getting the petrol system back up & running one day, as I'm sure it won't be helping having no petrol to lubricate but it does show that it is not as much of a problem as people think.
     
  5. The Slug

    The Slug Active Member
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    Standard S6 4.2 V8 is 340bhp.....i think the A6 variant is just under 300??
     
  6. a6george

    a6george Member

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    to run lpg the valves and valve seats have to be hardened, if the engine can run unleaded it has a good chance to be able to run lpg as it was the lead in petrol that acted like a cushion for the valves and seats. lpg runs hotter and so eats plugs,( put platinium plugs in). but if you get a good system and get it tuned/serviced at regular intervals you cant tell the difference between petrol and gas. I had a 3.2v6 frontera on gas and had no probs with apart from running a bit hot in summer, but I changed antifreeze/summer coolant mix to 50/50 and that sorted it. if I was going to change anything I would of put tanks underneath or in the case of the A6 put dougnut tank in spare wheel well.
     

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