Fuel consumption

BenS · Post by **BenS** » Thu Nov 26, 2009 7:49 pm

Running on LPG mine returns ~12mpg driving 25 mile each way journeys into the Peak District (on road) and once hit the heady heights of 15.5mpg on the motorway at 60. Does this sound reasonable? It no longer has a roofrack and has michelin xzy tires so not too much rolling resistance.

It has a luminition system although I will swap that for a Mallory Dizzy and RPI amp so that I can run more ignition advance on the LPG. I'm wondering whether I need to replace the camshaft (and associated gubbins). The gear box is from a range rover so I have higher (too high?) gearing.

Any thoughts or suggestions?

5988 · Post by **5988** » Thu Nov 26, 2009 10:28 pm

sounds rubbish then
does it rattle a bit , take look in the rocker covers that will give you a good idea how dead the engine is or isnt

my dads 3.5 RR would return around 20mpg most of the time (more with the 4 barrel webber )

ok its more aerodynamic but id imagine your not driving around at 60/70 all the time

my 2.25 petrol will do over 17mpg on gas when running at 65-70 for long periods ...id expect the V8 to at least match that

i think ill be able to beat that though once mine on the road ....i reckon about 5mpg is possible .....well have to try

ive managed 9mpg from a 2.25 before

sebking · Post by **sebking** » Thu Nov 26, 2009 10:31 pm

You don't ask questions about fuel consumption and drive a Stage 1 it's wrong!

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Mrs Bingham · Post by **Mrs Bingham** » Fri Nov 27, 2009 11:04 am

A Stage 1 was never intended to be kind on the pocket when it came to mpg. Gas only really provides less penny’s per litre and only marginal mpg gain at best. Add to that the extra weight of the tank etc then it makes no surprises that you return 12 mpg – I would accept that. As long as the old girl is running ok 13 mpg is as good as it gets increasing slightly on a good run. I’ve had as much as 19.2 mpg on a good run and as bad as 9 mpg on a stop start heavy traffic run without any change to tuning. I do run super unleaded with the timing set to 12 degrees btdc. It is worth checking out the cam but I’m sure it would be noisy if it were excessively worn.

Larosto · Post by **Larosto** » Fri Nov 27, 2009 9:50 pm

Hi,

I`ve fitted LPG too, and the consumtion is about 18 to 20 ltrs(100 km (sorry, `don`t know how many mpg this is at the moment).
In Germany it is much cheaper than running on unleaded fuel. Fuel costs about 1,30/ltr, LPG is 0,56/ltr. When I switch over from fuel to LPG the ignition point is earlier than on fuel.
I have SU`s fitted, restrictors out and engine overhauled. I use an overdrive.
If you have fitted a Range gearbox, you have to look at the ratio. Maybe you have overgeared. I did the same, and fitted a RR box with 0,9:1 ratio. The car had bad acceleration, so I changed ratio to original Stage One. You should notice that with the RR gear box your speedo is underreading, so maybe consumption isn`t as bad as you think.

regards

Horst

5988 · Post by **5988** » Fri Nov 27, 2009 10:56 pm

^^ works out at 14-15.6 mpg .....owch

was thinking they be around about 20 ish .....

going to be investing in a gas kit me thinks

BenS · Post by **BenS** » Sat Nov 28, 2009 6:08 pm

sebking wrote:You don't ask questions about fuel consumption and drive a Stage 1 it's wrong!

Fair point, I think it might be lacking power then!

larostos wrote:If you have fitted a Range gearbox, you have to look at the ratio. Maybe you have overgeared. I did the same, and fitted a RR box with 0,9:1 ratio. The car had bad acceleration, so I changed ratio to original Stage One. You should notice that with the RR gear box your speedo is underreading, so maybe consumption isn`t as bad as you think.

I don't know what a Stage 1 with a standard box is like to drive so can't comment, mines still faster than any other series I've ever been in! Speedo was reading out by ~25%, replaced with a 1000tpm speedo from a Triumph Herald which only under reads by 12%, but I correct fro this if I work out the mpg.

Mrs Bingham wrote:A Stage 1 was never intended to be kind on the pocket when it came to mpg. Gas only really provides less penny’s per litre and only marginal mpg gain at best. Add to that the extra weight of the tank etc then it makes no surprises that you return 12 mpg – I would accept that. As long as the old girl is running ok 13 mpg is as good as it gets increasing slightly on a good run. I’ve had as much as 19.2 mpg on a good run and as bad as 9 mpg on a stop start heavy traffic run without any change to tuning. I do run super unleaded with the timing set to 12 degrees btdc. It is worth checking out the cam but I’m sure it would be noisy if it were excessively worn.

Not too much additional weight since my LPG tank replaced the big rear petrol tank. I thought LPG had a lower calorific value so should actually lead to reduced mpg? Quite a noticeable ticking sound at low rpm, I'll have a look under the rocker covers when I've some spare time.

5988 · Post by **5988** » Sat Nov 28, 2009 6:19 pm

it does , but burns better so more of the energy in it gives you power ,you will lose some - probably a couple of mpg over petrol

V8_Disco · Post by **V8_Disco** » Mon Nov 30, 2009 9:53 am

My Stage 1 has LPG, I get about 12/14 on gas, dont realy run on petrol that much just enough to lube the carbs

I dont get 20 out of my Disco 2 when running on petrol, 19 was my best and I was drving like a saint after my mum

A

Jamie_grieve · Post by **Jamie_grieve** » Thu Dec 10, 2009 11:51 pm

On a 1 hr motorway run I get 18-20 mpg. Stop start 4 mile runs I get about 12-14. Off road, messing around, 30 mins/gal. Strombergs, 3.9litre, standard gearing, 900x16 tyres. 95Ron petrol. My Volvo gets nearly 12mpg (4Km/l) on a good day

It's my daily driver while I fix the stage 1!

Stage 1 V8

Fuel consumption

Fuel consumption

Eh