Average MPG for 1995 3.9l

Talking about mpg I've got 4.6 with LPG . Having trouble with LPG can anybody recommend good man in ol post code
Ps sorry for butting but don't know how drie this forum yet

From my 3.9 '93 Vogue SE, she would return between 12-14mpg on gas and between 13-16mpg on petrol, best she returned was 17mpg on gas on a run to bedfordshire.

Any more Pro's + Cons of LPG?

Found out ive got torpedo tanks, replacement petrol tank and boot tank in the car im looking and a 60 mile petrol tank and it automatically switches to petrol wen you run out.

A few cons ive heard so far...

To refuel with LPG takes alot longer that normal fuel

and my car will smell of fart inside.

Any more P+C apart from obvious ones ?
]
What about servicing costs etc? Can i still service the whole vehicle myself or does the LPG need checking regular ?

bigwilly said:

Any more Pro's + Cons of LPG?

Found out ive got torpedo tanks, replacement petrol tank and boot tank in the car im looking and a 60 mile petrol tank and it automatically switches to petrol wen you run out.

A few cons ive heard so far...

To refuel with LPG takes alot longer that normal fuel

and my car will smell of fart inside.

Any more P+C apart from obvious ones ?
]
What about servicing costs etc? Can i still service the whole vehicle myself or does the LPG need checking regular ?

Click to expand...

Yep depending on ambient temp and fuel station pressure, fill level of tank etc, it can take a while, and yer hand hurts after a while as you have to keep the button pressed....I learnt from a fellow RRC driver to lean on the button instead of holding it...helps a lot

Only if the tank is mounted internally, I had twin 40L tanks underslung where the main tank would have been and never had a gas smell inside....if they are external and you can smell gas inside, check all the piping and the vent valve for leaks ASAP.

Gas is 15-20% less efficent than petrol due to a lower calorific value (energy created during the burn) but is 50% the cost so expect a little less mpg on gas than on petrol.

Insurance companies like to see a test cert or installation cert for the LPG system, I never had one so had to pay a little extra premium for them to cover it (Admiral).

Always run the RR on petrol for a day to ensure the Injectors don't gum up, as burning gas all the time can cause the injectors to stick due to no fuel flowing through them...I used to run mine once every two weeks for 20 miles or so on petrol to keep things hunk-dunky.

Single Point Gas systems are prone to backfiring when the gas level gets low due to insufficent pressure, this can ruin the MAF unless you have the lovingly titled 'Fart-Flap' fitted....basically this is a one way valve that prevents the backfire from ruining the induction system.

LPG stations are getting more common, but check your local area and the areas you travel to often to make sure you have one available to you.

keep the system maintained (like the rest of the RR) and it will provide you years of trouble free motoring....I would love to still have my LPG converted RRC, but some nob-end thought nicking it and torching it was a great idea....

I will get gas for my 72 rrc but I have to have the single point style all be it with two mixer rings as its on twin SU carbs

I have the single point on me '92 3.9 and it works a treat. Get the gas system serviced though to keep it all tidy and stop back fires.

Cool . Had a look on LPGmap and there is enough for me. Presumably underslung + torepos + boot tank will give me a good few miles range between fill up - any idea how much ?

Going to have a look at it tomorrow - any thing i need to be looking it/for etc. cant test drive it as insurance isnt in place but going to have a good nosy and drive it up and down his yard abit.

I am running a carb converted 3.9 on LPG. at motorway speeds up to 70 mph I get around 18-20 mpg on petrol and 16-18 on LPG. Above 70, this drops to 15-17 mpg on petrol and 12-15 mpg on gas. Around town, the mpg is roughly the same for both, usually around 12 mpg max, but often quite a bit lower.

bigwilly said:

Cool . Had a look on LPGmap and there is enough for me. Presumably underslung + torepos + boot tank will give me a good few miles range between fill up - any idea how much ?

Going to have a look at it tomorrow - any thing i need to be looking it/for etc. cant test drive it as insurance isnt in place but going to have a good nosy and drive it up and down his yard abit.

Click to expand...

From a pair of 40's (most I squeezed in was 73L) I could get at a pinch 185-225 miles from it - never went more than 150miles though to prevent backfire and to ensure I alsways had a few spare miles in it....

Is that all

how big is the biggest spare wheel tank sutable for rrc?

how many miles would it bring on its own?, luckily my new house is minmum safe distace from an expensive lpg convertor who has cheap lpg for sale

bigwilly said:

Is that all

Click to expand...

225 miles out of 73L is 14mpg...

As I said I would get between 12-15 or so on gas....it is slightly less efficent than petrol, but 50% the cost....

Gas
73L @ 78.9p = £57.59
57.59 / 225 = 25.59p per mile

Petrol
73L @ 142.9 = £104.31
104.31 / 225 = 46.36p per mile

or 55% difference at 14mpg....

My LSE (4.2 not 3.9) averages between 10 and 12 mpg around town and between 16 and 20 on a run (depending on weight) when running on LPG. That's a bigas single point system that's only 14 months old and tuned regularly (you can do this yourself with the software)

Its fitted with 2 torpedoes and an upright tank where the spare wheel should sit. That gives me 130 litres usable gas with a range of about 290/300 miles around town and 400/500 miles on a run. It also has a full size petrol tank so on a trip to Spain last year when we couldn't find gas we managed over 800 miles between fill ups.

What you have to remember is that whilst running a V8 on gas is cheaper than on petrol, its still bloody expensive. And despite having a rumbling V8 under the bonnet don't expect performance to match from an aging Classic.

Buy one of these because you're an enthusiast or as a hobby or like the rest of us just plain mad!! Don't get one because you think running one on LPG is a viable option to an economic family saloon. If you do you will be disappointed.

^Wise words.

I considered the LPG conversion a few years ago but I seem to remember working out it was going to take me about 20,000 miles to get it to pay for itself. That was when petrol prices were lower than they are now though so have no idea how long it would take today. Not being a daily driver she only does 5K/year so it certainly wasn't worth it.

Apart from it being completely nonsensical for a sports engine the other thing that put me off was the range (not rover). I checked for stations that sold LPG near me and at my London address the only 1 I found was 2 postcodes across form me and I couldn't find one anywhere near where I live in Dorset.

I'd say it's well worth checking locality and the estimated return costs of the LPG conversion. Mine was based on a few people telling me not to spend less than £4K, the decent conversion may be cheaper now though.

Sorry to but in again. Dose anybody know of an LPG man in OL post code

Gasman62 said:

Sorry to but in again. Dose anybody know of an LPG man in OL post code

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