New to LPG - feel it should be better?

[2 rocks]

Hi there
So the County has LPG, I thought it might be a bit more economical than it is though...ok, it's hampered I guess by the 4 speed box and I have a 140km a day commute - half of which is in 90kmh zones so a 5th gear would really help.

However, the stamp on the tank says it would hold '81.8 litres of water'. On the two occasions I have now tried to fill it up - the red light was on the gauge - I can only get about 56 - 60 litres in it. I would have thought the ullage space would have been rather less than 20 litres! :eek:

It gave me almost 300km out of the first fill, this fill has just clocked up 200, with 2 "green bars" left on the gauge. So unless it does about 100 - 150 on the red light, hmmm...I'm not too impressed and I think it might be cheaper on petrol!

Any ideas on this? Does it just need a tune? I had hoped it might be about the same to run to work as the Td5, but at the moment it's dearer :eek:

Cheers
Mike

[isuzurover]

18-20 l/100 consumption sounds about right.

Bee-utey is the best person to help with tuning.

[101RRS]

You can expect 20% more fuel consumption on gas - the savings are in the purchase price of gas over petrol and not in its on road consumption.

Garry

[bee utey]

The legally mandated maximum fill level of an automotive LPG tank is 80% so your tank should hold around 65 litres from empty. It could be less becuse of errors are only allowed in the underfilling direction. Now you should get used to running right out of gas, the power drops away over a couple of km as the final tank pressure drops. (You may also hear a whistling noise from the tank) This gives you plenty of time to change back to petrol unless you have just hit a steep hill.;) Then check the fill amount.

Now as for tuning, you should be running more ignition timing on gas than stock, depending on your compression ratio you can run up to 12 degrees advance at idle. If it pings on petrol, run a bit of premium juice in the tank.

Your spark plugs need to be slightly different too, choose plugs one heat range colder than stock, and gap them to 0.7mm.

Finally identify your main gas flow adjuster, tweak it down bit by bit until you lose power, open it again until you have full power but no more. Most common lpg systems will run richer with a dirty air cleaner element so make sure you check the power adjustment after an element change, and anytime your economy drops drastically.

But yeah, gas is no longer the ultra cheap fuel it was 20+ years ago, so expect around 40% saving if well tuned, less if not. Personally as a gas fitter I'd be embarrassed putting such a small gas tank in a V8 truck, 70-80 litres would be better.

[loanrangie]

You can expect 20% less fuel consumption on gas - the savings are in the purchase price of gas over petrol and not in its on road consumption.

Garry

You mean more, the price off sets the consumption. I use to get 5klm/l in my 2dr 4 spd rangie with a useable 70ltrs out of the twin tanks (350klms), on a good run that would stretch to 420klms - this was with an impco 300a on top of a holley 350, bosch holden dizzy, mild porting but otherwise stock 3.5 .

[2 rocks]

B-U
Thanks as always for detailed info! That's good to know about running out - ok, I might sound like a tool - but I was concerned about that, in that I expected some kind of mechanically damaging backfire when it breathed its last.
On the occasions I've run on petrol it has pinged a bit so I'll remember to put some 98 RON in it, but until I can check I assume it's maybe timed for gas.
I'll change the air filter and check the plugs - when I can get through the plumber's nightmare :p:p

Got in to leave work tonight and the red bar on the gauge - odo reading 272kms. Drove with the green/red flashing for about 30kms before I stopped to put some in. Hmmm, filling every 2 days isn't filling me with joy - might be better off driving the Td5 to work after all ;)
Cheers
Mike

[101RRS]

You mean more,

Yep - thanks - edited my post.

Cheers

Garry

[ozscott]

20% for mixer. Basically line ball for injected. I really love paying 62.9 cents per litre. My D2 with roof racks, bar etc is like a 4cyl camry to run on petrol. and more torque than on petrol too:D

Cheers

[ian4002000]

If you are going to run on gas most of the time and you would like the best power and economy get your distributor recurved to suit LPG. You can run more intial advance but you need less total advance. It would pay to get it dynoed if you have anyone good in the area.
Dont lean your mixture out too much or you may burn valves.
And yep 60 something cents a litre is great and makes big savings in the long run.