lpg how far to your tank

ive got a 3.9 disco with twin under slung tanks , now ive been told there 36 ltr each how far do you get out of your tanks , ive just got back from corwall and from full to empty 175miles iwas hoping for a little more lol , or is this right also struggled like hell whilst towing (16ft caravan ) so not huge ???????

I've just got 170 miles on a single tank which holds about 70 ltrs (3.9 Rangie)

99 3.9 auto disco average 150 miles on 60 litres lpg [2x36l tanks] if this helps so yours is good

OK, well, first of all, tank 'Capacity' and tank volume aren't the same; there is a cut off valve that shuts off the fill at 80% full to allow for expansion, so two tanks with a 'volume' of 36l each will have a 'capacity' to hold 0.8x36=29l or 58l between the two.
Next up, towing, rule of thumb is to expect 2/3 'normal' fuel consumption.
Vans vary in the 'drag' they apply, and weight and length aren't actually so much important as the frontal area, which isn't much different whatever size of van you have.
Some longer vans actually cause less drag becouse the length helps smooth out the flow before the big void behind the back.
Fuel figures vary hugely for the RV8, and the disco doesn't fare quite as well as the Rangie, but you should be expecting figures in the mid-teens.
60l is 13 1/3 gallons; so 175 miles by 13.3 gives a rough MPG of just over 13mpg.... which doesn't sound too good, but taking into account the caravan, that puts your normal figures up to something in the 16/17mpg range, which is about right to on the good side.
Its the perennial problem of tank sizing for range or convenience. Bigger tanks mean less ground clerance, or filling the boot with them, or loosing the petrol tanks.
Small tanks can be a pain, BUT the problem is in having to fill up more often, and when you are on a long run, away from home and in unknown LPG terratory, that can be a problem and a wack in the wallet.....
But, its how you look at it; dragging a van away on holiday, you KNOW that you are going to be using more fuel, and that extra should be budgeted as part of the cost of the holiday, like the pitch fees and ice-creams etc! What you have to do is switch the accounting around, budget your holiday on full price fuel, and look at any saving from finding LPG en-route as meaning more ice-creams!

Hi
I have twin 40 ltr tanks on a d2 v8 . as Teflon said that will be approx 64l usable tank space. I get around 17mpg on a 'run' and 11/12mpg running around. Thats not towing so you sound about right.

fireman-andy said:

Hi
I have twin 40 ltr tanks on a d2 v8 . as Teflon said that will be approx 64l usable tank space. I get around 17mpg on a 'run' and 11/12mpg running around. Thats not towing so you sound about right.

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What speed do you cruise at on a run?
I'm doing a run on Friday on gas and wondering whether to cruise at 55 with the box locked up or run slower at say 45/50Dont know which would be more economical with a medium sized trailer.

I'm hoping for 15 + mpg or better. What are my chances at say 55mph.


by the way I told porkies earlier about my 170 miles on 70 ltr tank, it's actually 90 ltrs (checked it today)

Hi Landowner
I tend to sit at 65(ish) this is around 2250rpm I have only just fixed my cruise control (perished pipes) so this wasn't constant. 60mph when i was concentrating but often 70 and occasional 80. I do intend to set cruise at around 60.
I dont tow so I dont know what impact it will have. I know 50mph is around 1750rpm and the box is only just locked up. this may load the engine and increase consumption?
I dont know how heavy your trailer is but I would have thought 15mpg is reasonable at 55mph
What system do you have. mine is an AG sequential which is 5yrs/60000miles old but just been serviced and tuned. be interested in how you do.
good luck
Andy

Hi Landowner... in a 3.9, 57 would seem to be about the point that you can have it in 4th with the TC locked up and avoid it shunting gears too often.....
At that speed, doing a run from Nuneaton to Keithley & back, almost entirely on M-way, I managed near 25mpg on gas, with a single bike bike trailer on the back, and a 750-four on it on the way home! (bog all waight or drag tho!)
Taking the Caravan down to Somerset, trying to hold 55/57 on the motoway is a pain, with all the hills, and the load on the back, its constantly shunt-shifting between 3rd & 4th. Done that run a few times, and tried variose alternatives, cruising at 60, rather than 55, or selecting 3rd rather than D, to stop it shunting..... with 15ft van on the back, didn't make much odds either way, and I got around 12/13mpg whichever.....
So I guess depends on your 'run' and your trailer!
if its not too big or heavy, and you can hold 4th without it shunting, and its reasonably level, yeah, 15 should be do-able, I'd have thought, if not more.

Teflon said:

Hi Landowner... in a 3.9, 57 would seem to be about the point that you can have it in 4th with the TC locked up and avoid it shunting gears too often.....
At that speed, doing a run from Nuneaton to Keithley & back, almost entirely on M-way, I managed near 25mpg on gas, with a single bike bike trailer on the back, and a 750-four on it on the way home! (bog all waight or drag tho!)
Taking the Caravan down to Somerset, trying to hold 55/57 on the motoway is a pain, with all the hills, and the load on the back, its constantly shunt-shifting between 3rd & 4th. Done that run a few times, and tried variose alternatives, cruising at 60, rather than 55, or selecting 3rd rather than D, to stop it shunting..... with 15ft van on the back, didn't make much odds either way, and I got around 12/13mpg whichever.....
So I guess depends on your 'run' and your trailer!
if its not too big or heavy, and you can hold 4th without it shunting, and its reasonably level, yeah, 15 should be do-able, I'd have thought, if not more.

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That sounds promising then
I'll fill up and then see how far it goes on the tank. It's a 90 ltr tank so should hold 70 and I've got a 160 mile round trip over the pennines so cant see it getting me back without having to switch to petrol, but, you never know there's as many ups as downs
Watch this space.

Well, filled up the gas tank from empty and got 74 ltrs in it. Set the trip and off I went towing an empty medium sized galvanised twin axle trailer. Ran up the motorway (M62) at 55 mph which was showing 1900 rpm.
Collected a small ride on mower from a place near the Drax power station over on the wild side of he pennines about 80 miles away.
Came back along the M62 at 55 mph and lost all the green lights near Barton Aerodrome after covering about 134 miles, well 134 on the trip meter anyway.
I recon that I've got about 20 odd miles left at this point so the 3.9 V8 is doing no more on a run than it does knocking about town so I'm very dissapointed.
Neighbour was happy with his mower though.

My old 3.9 auto had the twin underslung tanks total 72 litres capacity, I could just squeeze 66 litres in if I ran them completely out.

As for fuel economy, when I first got it and it was unmodified on road bias tyres 18mpg was easy to achieve on a run with LPG.

After a 3" lift, 265/70 mud tyres, winch bumper, roof spots etc I think I blunted the fuel economy somewhat as 12 to 14 mpg was then the norm

I found towing, (particularly down here where it is so hilly and most roads don't allow you to maintain a high enough speed to lock up the autobox) an absolute nightmare - got the economy down as low as 9mpg!!:doh:

The 3.9 I have now is a manual gearbox, I get 21 mpg on a run to Kent (on very aggressive mud tyres), hoping for a lot more now I got my girlie 'summer' tyres on - not bothered to gas this one, happy with things as they are for now.

Ta for that, I'd be more than happy with that but I only get 12 on gas which I think is bad especailly as I drive carefully and rarely excede 2000 rpm.
I think I'll have to tune the gas a bit as it could be running rich, there are no leaks anywhere so the gas has got to be eaten by the engine.
This lot of gas hasn't run out yet though and I've done 190 miles on 74 ltrs with still a bit left.

room for improvement I think.

i get about 48 ltrs in my twin tanks and that usually gives me a range of 100 miles so roughly 8 mpg... very bad i know but i do rag it silly lol
talking of routing your journey via gas refilling stations i find that this
Go-Autogas - LPG Station Map with Refuelling Garages on Map with LPG Prices and Sat Nav Download
is one of the best free links as it lets you know where the nearest is

My 4.6 hse Rangie typically does 200 miles before it asks to switch back to Petrol. No idea on the overall capacity of the tank but a refill from "Empty" is about 68 litres. It seems not to matter whether I drive gently or not, it doesn't really vary.

The onboard ECU seems to indicate it thinks we are getting 15.4MPG on a long run.

Not stunning MPG by any means (i guess the "BRICK" aerodynamics don't help)

Regards to all.

Dan.

Hi , i have a 4.6 rangie and a 95litre lpg tank, i get 240 to 265 out of the 80 lites of usable gas, i had the installers to tweek the float a bit for me.

hi, ive a 3.9 1997 disco, on a recent run here in ireland i got 177 miles for 62 litres of gas, towing a large caravan and doing 55 to 60 most of the time.

cheers

metropolis2 said:

Hi , i have a 4.6 rangie and a 95litre lpg tank, i get 240 to 265 out of the 80 lites of usable gas, i had the installers to tweek the float a bit for me.

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OK, this sounds decent. Although, looking at it, I've managed to get 390 miles out of my petrol tank before needing refilling. Seems like most people running on LPG need to fill up more than twice to get this distance. Gas prices round here is £0.64 p/l, making it £1.28 p/l to go the same distance as me on petrol.....I dont see the advantage of LPG anymore.

52.9p /ltr here in surrey

lpg only 45p around here happy days

Mines working out at 11 or 12 to the gallon on gas which is only just better than using petrol. I was expecting 15 mpg on gas but with a lot of town driving then that isn't going to happen.
Happy days indeed.