How Many LPG'd

I have an LPG'd BMW v8 engined Range Rover

how does the M62 V8 drive on LPG?

its a good idea, although you have to do a considerable mileage before you see any return on investment...

and then theres the case of finding a station with LPG in the first place... good idea if you live on the doorstep of one i guess.

I had my 840 M62 converted a couple of years ago and couldn't be happier; I do a lot of motorway miles so I have recouped the cost multiple times. LPG filling stations are in my satnav as points of interest so it's quite easy to find them en route.

When running on LPG in the Rangie the only difference is that the engine is a bit quieter and runs just slightly colder, but on the upside it returns the equivalent of 27-28 mpg

Not entirely relevant I know but, my 1996 Rangie (Rover V8 4.6ltr) has a sequential LPG system fitted and it works excellently. I know this sounds daft but it does seem to actually run better on LPG than on 98 octane. I don't really notice much of a drop in power. The only downside is range - I have an 80ltr tank for LPG which actually translates as being able to tank up around 65ltr (you can't actually fill an LPG tank) and that is enough for around 200 miles before I need to either switch back to pertrol or find an LPG seller.

Propane is around 110 octane, so if the engine is tuned for it you can actually get more power running on it. The proper way to optimise for it is raising the compression ratio, which improves power and efficiency. But then of course you can't run on petrol as it'll ping due to crappy 98 octane fuel

The reality is that a modern engine (like the BMW V8s, not sure if the V12s do this) will automatically advance the ignition to just before the point of knock, which will mean more advance on propane. The lower calorific value of the fuel means you'll burn more per mile (by usually 10-15% if it's running properly), but it doesn't necessarily mean less power - bear in mind that diesel has significantly higher calorific value than petrol, but it produces very little power without the help of forced induction, due to slow burn!

Engines often show less wear too, as you don't get oil dilution and bore wash to the extent that you do with petrol. Combustion temperatures are slightly higher, which has proven to be problematic with some chocolate engines (Ford Zetec valve seats anyone? ) but on a decent engine with good margins, there's no issue at all.

I considered it for mine a few years back, but quite simply it would have been madness as I have a second car and do very few miles in the 8. Hence still paying 30-35p/mile in fuel

My 840Ci has been LPG'd. I'm currently paying around 48p a litre for LPG though some stations are up to about 60p a litre. For about £30, I get around 200 miles. Great value but installation was around £1500.

Performance is still good on LPG but on petrol, she runs super sweet as opposed to just sweet. @;o)

The guy who installed the system said it was the only 8 series he'd worked on and it was tricky but doable. I now have no spare wheel as that's where the LPG tank is. Worrying but it's got to be done.

Had an issue with having to lose the washer bottle that's situated in the back of the car so have to fill up with water for the wipers a little more often but no big deal.

Well worth doing...

LPG conversions in E31´s are very rare over here as most people rather keep the car the way it is and do not use it as a daily driver.
I know of one person who converted his S70 V12 to be fed with LPG. This is the result:

This was done to one of the last 100 CSIs - my feeling is that the car has been defaced and devalued only to save a few p on gas but this feeling is probably common with people that see more than a car in an E31

Reinhard

Egads Reinhard. The horror.