What kind of range should a 3.9v8 be getting on LPG? (mine may have problems)

[Young Angus]

I've had my v8 for a while now and I've been logging the km's every time I fill up. According to my calcs I use 25.7 litres per 100km. From what else I've read this seems high.

I just had the gas serviced and tuned and I haven't filled up since but it's looking like similar millage. The converter was replaced (apparently it was all gummed up) and they gave it a proper tune (not sure if it was a dyno tune though) over at Range Rover Automotive in Vermont who claim to be LPG experts.

I put new Bosch plugs and leads on it not too long ago and it hasn't backfired since, I also attempted to set the timing to 10 deg BTDC but I'm not sure if the garage would have changed that during the tune.

It's running really well and I hardly notice much difference between gas and petrol so I'm not complaining there, but from what I've read I should be getting better millage than that. It's all city driving and it's a manual, and I don't drive it hard! It's not gas injection or anything just a standard gas setup I think (photos will probably tell you).

[Landover]

That's about what I get on the hwy. Usualy get around 33l per 100km combind hwy and low range driving when out for the day. Gives me a range of 150 to 170 out of 55L. It's lucky I still have the full size petrol tank to give me some range. I run 31" tyres and have a bit of bar work front and rear and roof racks putting a bit of weight on. It's a good thing it's not my everyday driver.

[discostig]

hey mate i have a 94 series 1 3.9 on gas too, i have a 45 litre tank and on highway i get 400 k's havent really tested out the fuel cause the gas is too cheap at moment. you have got a similar set up to me under the hood but i have a defender air intake not the rectangle one you have.

[Duffman]

I have a 96 v8 5spd with the twin tanks in place of the fuel tank and i get 400k's.
my under hood setup is the same as yours.

[Young Angus]

So something isn't quite right. Would the advanced timing have anything to do with it? (10 deg BTDC)

[blitz]

I have a 60 lt tank and after a year of running it in the city and in heavy hills in a 94 disco with a 4.6 in it with an auto gearbox I get 250km per tank.

Having said that Busy Bee just tuned it for me after I had it done at a "reputable" landrover specialist about 4 months ago, the difference is spectacular so I will have to do it again to see what it is now.

My advise is ring around and find a LPG service specialist because if you have had the timing set back to 'standard' by the people who last did it for you, then they don't know what they are doing when it comes to LPG

[Young Angus]

Well I can set the timing myself if need be but from everyone's findings it sounds like my LPG economy should be a fair bit better than what it is currently. I just filled up for the first time today after having it tuned and I got 220km out of 65 litres...from what I've heard everyone else gets that sounds like pretty rubbish economy.

The place that tuned it claims to be LPG specialists, and a dedicated Land Rover place to boot (Range Rover Automotive in Vermont) so I don't see why they wouldn't have it all under control but surely there must be more to it than that, even without going all out with a dyno tune and oxy sensors or whatever else I've heard people doing.

Any suggestions for LPG specialists who people have had good economy results from after a tune?

[bee utey]

Hey why don't you try adjusting it yourself. The main mixture is on the mixer right by the 1 inch gas inlet hose. Look carefully and you will see L and R marks. Move the adjuster 1 notch towards the L and try again.

[Young Angus]

I take it L is for lean and R for rich?

[101RRS]

I would say that is poor economy though 10 degrees BTDC is about right.

My 101 brick with its extremely poor aerodynamics does better than what you are getting - just covered 1000km in the 101 in two days and averaged 23 l/100km on gas.

Garry