LPG conversion on V8 models

Newbie Joined: Oct 25, 2011 Posts: 7

Hi,
Im new here so apologises if this has been discussed to death already but I want a V8 RS4 but just cant live with that fuel consumption everyday.

Ive done a bit of digging on the net and word is if you get it professional done it seems a safe enough thing to do - some reckon its even better on the engine than petrol? My calcs reckon a £2k conversion should pay for itself after a year and a half with my mileage so I should be quids in after that.

Trouble is Im not convinced the government are going to keep the price of LPG down and if it goes up Im stuffed - any thoughts out there on commitment to LPG???

cheers guys

Mark.

Posted: Tue Oct 25, 2011 9:10 pm

The V8 RS4 engine is an FSi engine (direct injection) and currently no LPG kit exists to deal with this although I hear they are being developed.

I don't know if the tax will stay at the same rate on LPG in the future, it's worth asking on one of the LPG forums.

I run a V8 Mercedes on an LPG system that I installed myself, it's only 2mpg worse on gas but with the benefits of 75.9p/litre and no noticeable performance loss. Smile

Newbie Joined: Oct 25, 2011 Posts: 7

Thanks for that mate

bugger, didnt realise that about the FSI, I guess the older V6 is ok though?

There are lots of references out there about LPG on S6's and RS6's - presumably thats a different engine then???

Would go for an old RS6 as a stop gap as theyre half the price but dont really want an auto!

cheers

Posted: Wed Oct 26, 2011 10:31 am

I run a V8 Mercedes on an LPG system that I installed myself, it's only 2mpg worse on gas but with the benefits of 75.9p/litre and no noticeable performance loss. Smile

[/quote]

Just a quick query.. As i am thinking of doing this myself odn a different audi, truth be told how much petrol do you still use a week?
People don't tell ya that, but the car still runs on petrol until the engine has warmed up (the time it uses the most fuel anyway so short journeys the lpg is no saving at all surely?)
Or am i wrong?

TIA
Dan.

Posted: Thu Oct 27, 2011 12:16 pm

Just a quick query.. As i am thinking of doing this myself odn a different audi, truth be told how much petrol do you still use a week?
People don't tell ya that, but the car still runs on petrol until the engine has warmed up (the time it uses the most fuel anyway so short journeys the lpg is no saving at all surely?)
Or am i wrong?

TIA
Dan.[/quote]

The basic rule of thumb is to set the LPG system up so that the engine switches from petrol to LPG when the engine coolant reaches approx. 50'C as you need the coolant warm enough to start vapourising the liquid LPG supply from the tank.

In summer this doesn't take long on an aluminium block engine, maybe 2 miles of driving from cold. In winter it can obviously vary. Some people set their system up to run from LPG from the start but the engine can run rather lumpy as the fuel mix can be overly rich as the LPG will not be properly vapourised.

Audinutty, the previous C5 platform V8 RS6 is able to be LPG'd although it would require an installer who has done the conversion before as the power requirements are at the limits of what LPG can deliver based upon injector sizes.

Posted: Thu Oct 27, 2011 12:39 pm

Thanks for reply, my own car is a different more complicated beast to convert (2.3 NG engine) iron block i think, that and i need a standalone engine management system to use the newer multipoint systems.......
The car has only now got just over 53000 miles on it, and i intend keeping it till its wrote off or rots lol
Just still can't make my mind up if it's worth the hassle or not considering by the time the standalone ecu is sorted i'm looking at around £800 before i fit the lpg kit.....
sorry for the thread hijack btw lol Embarassed

Newbie Joined: Nov 27, 2012 Posts: 1

Hi, new to forum and realise about a year late on the discussion, but if anyone's interested I have had both my wife's 1996 2.6 V6 converted - about 6 years now and my S4 4.2 V8 for 3 years (prins system) both running with no problems - converted by an approved installer. Makes running the cars economical and in terms of performance, with a quality conversion and properly setup you really don't notice under normal driving. Have recently purchased a 2006 A4 2.0tFSI Quattro. Direct Injection - BRC do a system (http://www.arunautogas.co.uk/). Costs around £1800. Speaking to them about converting the new car. I'll let you know how I get on. Smile