XC70 3.2 lpg conversion?

[Qube]

I have a 2008 3.2 XC70 (not T6).
It has 80,000 miles on the clock.

MPG not so bad on longer journeys (27), but city driving closer to 19-22. Was thinking of an LPG conversion.

Can anyone advise whether an LPG conversion is possible. I've searched around here and online and can find no examples of others doing it/having had it done. Are there issues with VSR with this engine? (is it the same as the xc90 engine - which apparently does have potential VSR issues?).

Is the spare wheel location for the tank a limiting factor on a useful size. I think the spare wheel space in the XC70 is smaller than the equivalent V70 space- I was thinking 65 litre tank as a minimum.

Which system to go for? Obviously the newer VSI systems seem to be more efficient, but more pricey. However, I don't mind investing in the car and I'm looking to keep it for 10 years longer, as it is a nice smooth drive, with all the goodies I need. I've worked out that the conversion will be amortised after 30,000 (assuming £2,250 conversion cost).

Very grateful for any advice.

[classicswede]

The engine is the same as the XC90 3.2 engine. I've always fitted a basic valve saver system as a precaution as many Ford engines do suffer with VSR. I suspect these engines are actually OK bot for what a system costs you might as well have it fitted.

A 70ltr tank will fit in place of the spare wheel.

The 3.2 does need a calibrated fuel return fitting

[Qube]

Thanks for the info classicswede.

Do you mean that the car ECU has to be calibrated after a period of running it?

Do you have any experience of liquid injected systems (Vialle LPI, is one I've read about)? Seems to run cooler and no discernible difference to petrol use (in terms of power).

[classicswede]

Nothing is done to the petrol ECU, it is only read for calibrating the gas.Liquid injection is still in very early days with them and the tank range is very limited. They do have advantages but the support is just not there for them yet.

[Rversteeg]

I am not sure, but I seem to remember that liquid injection of LPG is not allowed yet in the UK. Saying that liquid injection is still in its very early years is not entirely correct. I am running a 940 LPT with a Vialle LPi liquid injection system for over 15 years and 300K miles, like most post '96 940 owners here in Holland. Tanks are the same as for any other system (52 l net in my estate, twinned tank in the spare wheel bay).
Indeed no power loss, even a slight power increase because of the cooling effect of injected LPG on the air/fuel mixture. No risc of backfire, runs perfectly with turbocharging, even when tuned. The system converts the injection signal for the petrol injectors to a suitable signal for the LPG injectors, so it also features sequential injection (not on 940). No changes whatsoever to the existing ECU, just an additional LPG ECU for recalculating the petrol injection signal. All fail safe components; take out the LPG system fuses and the car runs on petrol as if no LPG system was installed.
Some known issues are the lifetime of the in-tank LPG pump of the earlier models. If it fails (and it will after 200K or so) the complete tank needs to be replaced, which sets you back a €.600-700,- when done by Vialle (cheaper means available). Later models have an external pump. The pumps can also be a bit noisy. Furthermore the relay shutting down the petrol onjectors when running on LPG is not particularly reliable, later version should be better. Finally the LPG injector seats in the inlet manifold (fitted by Vialle to standard Volvo manifold) sometime become loose, causing bad running because of air leaking.
I would not hesitate to buy it again!