The V8 Owners Forum -

Hi everyone really enjoy the site and have found it a great source of information.


Anyway have a 2003 4.0 disco auto with a few mods.


4.6 rods & crank
stump puller cam
10.5 compression ratio
Zavoli multi point LPG system

My query is 12 mpg all the time

120 mph = 12 mpg
65 mph = 12 mpg
stop start in town 12 mpg
towing the big caravan 12 mpg

All worked out from full to empty and not on a trip computer. So getting near nye 240 miles to a fill every time.

The question is surely I should be seeing some sort of change in fuel comsuption form blasting down the road to cruising down it.
I know she's a little down on what I used to get (14 mpg) but put this down to needing a service.
Anyone got any ideas

thanks kev

Hi Kev, interesting you say that about fuel consumption...

I have a bog standard 1998 3.9 Disco 1

it is unmodified apart from the old (unknown) single point lpg system

i have owned it for almost 2 years and now covered 43000 miles

i have never managed 120 mph (not capable!) but at a steady 80to 85 mph i get 14 mpg
at a steadyish 65 it gives me 14mpg
stop start round town - 13 mpg
pulling a heavy double axle calf trailer - 13 mpg

yeah hardly any difference with mine either... i had noticed there wasnt much difference in but i've always just put it down to the v8 having so much torque it doesn't even notice that there's a trailer on the back

now I'm as puzzled as you are!

dave

Hello there Dave
Started to think I had the lergy with no relies.
Did have a P38 Range Rover Supercharged Overfinch many moons ago.
On petrol not gas, got just over 21mpg at 70mph and wait for it around 6 when driven hard.
I think your right on the towing side as the disco goes like a freight train and have to keep looking in the mirrors to remind me that I have the van on the back.
Anyway will be dropping her into Energy Shift when I get back from the hols, just to see what they think.
Will post what Mike has to say.

kev

My 3.9 range Rover Classic on gas injection (Bigas) runs @

15mpg steady cruising motorway @65ish

12-3mpg aroung the doors

10-12mpg towing depending on weight carried (3.5t rated trailer/caravan)

Thats the sort of figures that I would expect Royston.
But 12s across the range?
Just can't make it out

kev

I know it's been a while, but what ignition advance are you running?

I couldn't nget more than 10mpg when I first converted to LPG, after a bit of thought and research I advanced the origonal (6 deg BTDC) base timing +10 degrees, the engine note then transformed itself and saw a real improvement

Ignition Advance?
What's that?

It's a late Disco 2 (2004) with the Thor set. No dizzy.
Would love to play with the advance but it's the Bosch Motronics system. From what I know this can't be played with and is always being adjusted by the ECU.

Thanks for the suggestion Softdash3.9 and sorry its been so long.
Still waiting on my brother to finish getting it back together. Keeps telling me hasn't had the time lately. But has the time to buy a bl***y puppy
Anyway as soon as its back on the road will let everyone know what improvements have been found if any.

Thanks again
kev

Im guessing you have a mean average showing on the MPG meter, dont know how yous works, but try zeroing it and the watch it while you drive, if it has been collecting data for a while, it becomes slow to react with the more miles you have on the clock

Not as posh as a Range Rover. Have to work it out from full to empty.

kev

My Disco II 4.0 returned about 15 on cruise, 13-14 on a fairly fast run, 14-15 towing and 12-13 round town. Very little difference really.
My current vehicle (5.7 V8 Hemi) returns 21 on cruise, 18 "spirited driving" and 19-20 towing, all on gas. On petrol it will return up to 28 cruise, but more normally around 24.

I've got a 3.5 pretty much standard apart from a unknown upgraded cam, edelbrock 4-barrel set up, a Mallory duel points and a RPi LPG sysyem with RPi AMP.

I've got this little lump in my Ex Ambulance LDV Convoy with is loaded most of the time weighing in at approx 2.8-3 Tonne! I manually calculate my fuel every fill up and I only use the LPG.

Most of the time and I get 10-11 pretty much all day long short journeys, long journey. When I'm on the motorway I might be lucky and get 12-13 but the motorway is not a place I end up often!

Like yourself I can't work it out

I have an Audi A6 quattro sport on LPG which does 26 on petrol general driving, 31 on a run and 14 around town or having a laugh (which you have to do )

I get 19 on LPG whatever I do.

My P6 will have LPG soon - we'll see what that does to the gallon