Cheaper than my minis

[Deleted]

After my first long run, 180 miles of motorway/fast dual carriageway work, i got the calculator out and worked out my MPG on the LPG.....22mpg!!!! and at 48p a litre that means the P5B is officially my economy car
I suspect it helps that the ZF keeps the revs right down to 2000 at cruising speed, so the engine isn't really working hard...still, a damm site better than my old P5B that struggled to do 16mpg.

Ian

And no, i wasn't doing 50 all the way before you ask, a steady 70 to 73mph (GPS) with a few dashes to 85 when the need to overtake a modern overcame me.

[dorsetflyer]

That's not bad at all Ian. However if your P5B was only doing 16mpg I would have thought that the engine was way off tune and needed looking at.
On a run similar to yours, mine normally does around 25-26mpg, and that's travelling at road speed limits (hopefully).
The best thing is that LPG is much cheaper than petrol at the moment, so it's an added bonus. Mind you it takes years to repay itself fully.

[Deleted]

25 to 26 is outstanding. LPG is a bit tougher to burn than good old petrol, so i should be seeing 24-25mpg on petrol on a run, not that i use petrol much for obvious reasons, normally just the little trips around town.
Agreed about the cost of installing LPG, but mine was installed by a previous owner, a very nice Dutch man, so he swallowed the cost, it's a rather old an inefficient LPG system, so I may upgrade it...see if I can get close to your 25-26mpg target. Although I doubt it......Is your engine standard?

Ian

[dorsetflyer]

It's totally standard except for 'Lumenition' ignition, and runs usually on Shell Optimax with Castrol Valvemaster Plus added.

[Deleted]

When i do use petrol I'm a BP ultimate man myself, Optimax at a push...not that either make a blind bit of differance to performance, but hopefully the cleaning compounds will prolong the life of the engine.

Ian

[dorsetflyer]

If I wanted BP it would mean a round trip of 20 miles, whereas for Shell it's a round trip of two miles, so for economy Shell wins, although if I'm out on a trip and need to re-fill, then either of those will do together with additive.

Mind you my youngest son is right miffed, his BMW does 28mpg, and as he says, my cars are much more comfortable and roomy than his.
Do I smell a possible Classic Car convert in the future?
I know my eldest son has always been into the classics, but unfortunately cannot afford one yet. He's a Rover fan of P4's, P5's and P6's.

[shed]

Hi All,

After a week of ownership of my P5B Saloon, I've done about 600 miles, a 400 mile round trip from London to Devon and 200 miles on the London commute.

In stop/start traffic rarely getting above 20mph the car averaged 16.5mpg.

On the 400 mile round trip it managed 25.6mpg at steady 70/80mph.

I was pleasently suprised, and a breath of fresh air compared to my Mk1 Jensen Interceptor!

Cheers,

Steve.

[Deleted]

So 25mpg appears to be the benchmark then, the gaunlet has been thrown down

I'm off to Luton today via Leighton buzzard, back tomorrow, should be a good 220 miles at least, I'll see if i can better my rather poor 22mpg

The trouble i have is that my cruising speed has drifted from 70 to 75, and now sits at 75 to 85, best i slow down a bit if I'm going to match these figures.

Ian

[dorsetflyer]

Keeping a light and steady foot on the throttle enough to keep the speed constant is the course I use most of the time on a long journey involving motorways, and it seems to pay off.
On the round trip to the National last Sunday of about 270 miles, I made 24mpg. This is slightly down on my normal figures, but I did play games with 'white van man' and other clever clogs who thought that come the first hill, they could get by me. Wrong, because as they pulled out in the next lane, my foot sunk to the floor, and it was a joy to see them disappearing backwards in the distance. White man van stood no chance whatsoever. So I did have some fun on the journeys at the expense of a couple of miles to the gallon.

In October I will be up at Woburn Abbey with one of my classics, but it's too early to say which one will have the pleasure. That too will involve a trip through Leighton Buzzard.

[Deleted]

I have a friend who has a Paramount car that was made in Leighton Buzzard. Not many of these cars left now.

[johnwp5bcoupe]

59fan is the engine running at the same temperature? I was chatting to a breaker of Range Rovers and he reckons there is a problem on them overheating on LPG causing liners to slip head problems etc perhaps it's the later type V8 that suffers?

[Smallfry]

I have never heard of a liner slipping on a 3.5, although I have about several on the larger bore engines (3.9 and up) and this is not confined to LPG engines

[johnwp5bcoupe]

Yes he did say 3.9 that why I was asking if the problem was not apparent on the 3.5 which is good news! he also said the majority of requests for s/h engines was from LPG users

[Deleted]

It runs at the same temp on either gas or petrol. i guess it would only run hot if it was lean.
The 4.6 and to a lesser extent the 3.9 do suffer from cracked blocks and slipped liners if they suffer too many overheats. This problem is more noticable on later range Rovers as they had to run hotter to sort out the emissions, this and the fact that the top hose is prone to bursting make for a bad combination.
Definately an engine issue rather than an LPG one.

Ian

[johnwp5bcoupe]

Thanks Ian I am wavering about doing a LPG conversion hence my interest

[harvey]

smallfry said:

I have never heard of a liner slipping on a 3.5, although I have about several on the larger bore engines (3.9 and up) and this is not confined to LPG engines

I used to sell V8 engines to a friend who did V8 conversions on older Land Rovers, and he would overhaul them before fitting.I had one 3.5 litre that had a liner that had dropped by about an eigth of an inch.But that was the only one.
He's still involved with the later Land and Range Rovers and has had a lot of liner problems with the overbored V8's particularly the 4.6

[stantondavies]

If you are going for LPG be sure to DO YOUR SUMS and have them scrutinised by someone independent who is used to analysing figures.

[johnwp5bcoupe]

It's not just the economy it is also the cleanliness both to the engine and the environment as I said in previous replies in another section £600 to £800 on a full restoration built in as part of it is not to bad others may say it's loads of money then spend £800 on re chromed wheels or £300 or so on carpets it's whatever floats your boat

stantondavies said:

If you are going for LPG be sure to DO YOUR SUMS and have them scrutinised by someone independent who is used to analysing figures.

[johnwp5bcoupe]

The guy near me who brakes Range Rovers has an early 3.5 coming in that has been run on LPG for the best part of it's life 165,000 miles he is taking the heads off so I can have a look! should be interesting

[Phil Nottingham]

That will be interesting as some conversions strongly recomend an additive to prevent VSR as LPG is more aggressive than ordinary unleaded

[johnwp5bcoupe]

I will let you know what state the heads are in Philip and whether a flash lube is fitted?