Volvo LPG Conversions - What is the best car and system?

[SteveV40]

Hello all... My trusty 2002 V40 1.8 SE BiFuel which I got at 60k has now passed 250k, and is still going strong. To extend its life I am thinking of semi-retiring it but I have a dilema over whether to jump to diesel (gulp), or to look at a more modern petrol vehicle 2-5 years old, and have it LPG converted since Volvo have stopped the BiFuel models. I currently get a real all in average fuel cost of 14.1 pence per mile, based upon 4 months careful recording over a distance in excess of 12,000 miles (mainly out of town and on motorways) and filling the petrol tank when doing the main calculation. That gives me an equivalent of almost 45MPG, based upon fuel cost. My last full fill to full fill delivered a cost per mile of 12.69 pence, although it is warmer now and both fuels have been cheaper recently. To match the 14.1ppm average, I would need a diesel to give me 45mpg on the road (not "official" figures) and I am looking for an improvement to 60+ really.
So.... Does anyone have any thoughts on what petrol Volvo would give me a long life and a 60+ MPG (equivalent) with an LPG conversion? And what conversion would be the best? I do about 35k+ per year, so the base costs are not the real issue, but running costs are. I have to say, my BiFuel has been fantastic. Any help would be very much appreciated. Many thanks. Steve.

[Pete_c20]

Hi Steve,
I can't help you out on which modern Volvo or which LPG system but one thing I would say on choice of LPG system, if you do go that way, is to look for a fully active LPG system. My reasoning is this -
After rebuilding my S40's LPG system (Necam / Koltec system with passive injectors) due to a progressively worsening LPG economy, I found that even though it's been setup with the correct pressures it's inadvertently become slightly optimised for long motorway runs. I now get about 10% more miles out of a tank than even when the car was new. However, urban cycle is now slightly worse. It makes me think that a system that was better mapped/dosed at both ends would be a best of both worlds. As it is I think I have a single point of optimisation.

[SteveV40]

Many thanks Pete. You are commenting on an area in which I have little knowledge, as my LPG experience is only on my BiFuel, so thank you for sharing it with me. I am curious as to what kind of economy you were getting on your original S40 system, as that is the same system as mine. I have been very lucky with it, as it has never had a "proper" service, although I have changed filters and cleaned the distributor. I should really put another thread up on what constitutes an LPG service, as I am sure I would learn from it! Many thanks again.

[Pete_c20]

Aircon which is known to reduce your fuel economy has never been turned off in the car, so if it had of been, these figures would probably have been better.

At new on motorway, with 43L of LPG I usually got between about 250-260miles, with 270 miles absolute max (constant 70mph, one continuous trip, wind blowing the right way, wing mirrors folded in).
At new, non-motorway was usually 180-220miles from 43L of LPG.

NB. My tank capacity has reduced from new (see new thread) so LPG figures have changed in this next bit.
Before vapouriser diaphragm was fixed (it had gone all sticky and had began to disintegrate but hadn't actually pinholed) motorway and urban were not much different and on a bad day I'd get only about 100 miles to about 40L of LPG. But the car still ran fine.

After the vapouriser was fixed I get 270-290miles from about 40L of LPG on a motorway, and 160-190 miles urban.

The car has one code showing in the basic OBD2 readout and that is its longterm fuel trim being 5% rich, which I'm still figuring out, but could also explain its bias to better fuel economy on longer trips. I don't have a DICE ODB2 reader to see all its bits.

[SteveV40]

Those are impressive figures! I have never got anywhere near.. the very best I have ever achieved is about 210. Did you overhaul the vapouriser diaphragm yourself?

[classicswede]

For conversion you can rule out the 1.6 as its slow and poor on fuel. The 1.8 GDI is a no go as you have to run a petrol/lpg mix to keep the petrol injectors functioning.

Best engines are the 1.8 and 2ltr

Both the T4 and T5 can be done if you are looking for more of a performance car.

[Joe Harding]

Converting a 340 1.4. Great fun, no regrets.

http://www.volvoforums.org.uk/showthread.php?t=177298

[The Thong]

If its any help, I have a 2ltr S60 that's fitted with a BRC system. Apart from a minor glitch with a pressure gauge I've had no issues. The cars getting 28mpg on a run (my cars an auto) with AC running. It's well worth the investment if you're considering doing long distances.

TT