Mudplugger

I'm looking at an Allroad 2.7T on eBay that's fitted with a LPG conversion (I'm in the UK and petrol is hideously expensive, so at 30,000 miles/annum I need LPG or TDI motor) but wonder how long it will last?

Does anybody have any experience of covering a high mileage with a 2.7T engine running on LPG?

If so, how long can I expect the valves/seats, and perhaps turbos too, to last before I need to rebuild?

Thanks,

Andrew

quickaudi:STFA

no clue

fjasper

but that won't stop me. From what I've heard, running engines on LPG or CNG is usually easier on them than running on liquid fuels.

Mudplugger

The experience of friends over here tends to suggest that LPG lacks the lubrication & cooling properties of petrol, and that exhaust valves and/or valve seats suffer as a result. One who ran a brand new Toyato Aygo on LPG burned out a valve within 60,000 miles, and there are numerous reports of Volvos with aftermarket LPG conversions suffering after similar mileages on the fuel (the Volvo factory-fitted LPG cars use different cylinder heads...)

On the other hand, the Ford Mondeo 1.8 petrol engine appears completely unconcerned about LPG and numerous taxis have covered 200,000 miles or more running on this fuel without problem.

The obvious conclusion is that different manufacturers build to different quality standards, with some engines clearly more suitable for conversion than others).

What I was wondering therefore is if anybody knows where the Audi 2.7T engine fits on this production spectrum, because that determines whether one with an LPG kit is a potential bargain (because it has a £2,000 conversion "thrown in free") or a potential liability (because it will shortly need a top-end engine rebuild).

quickaudi:STFA

if it's anything like the old diesel engines from the states with the new diesel fuel, you'll have to add some lube in manually with every fuel fillup, like Lucas Oil fuel additive

Mudplugger

Unfortunately LPG is stored under pressure (both at station and in car) to keep it liquid and stop it vapourising, so adding anything to it when filling up the car is impossible. The only way to introduce an additive would be to plumb in a second injector especially for the purpose, wired to go live whenever the car was switched from petrol to LPG. It's not impossible but it does add to the cost, and if necessary certainly makes the 2.7T a less attractive conversion proposition (and without conversion the price of petrol excludes it).

There's no denying it would be easier to get a 2.5Tdi but 2.7Ts are very much cheaper over here.

quickaudi:STFA

do they put seal lubes in there?

Mudplugger

As far as I know, LPG is literally just "liquid petroleum gas" with no additives whatsover.

It's sufficiently "standard" or "raw" that I have removed the (exchangeable) butane/propane cylinders from my motorhome (RV) and replaced them with a refillable LPG tank than runs cooker, heating etc. (The vehicle engine itself is diesel)

A friend of mine without mains gas (a vapour for heating homes and cooking, not petrol - our common language gets challenging sometimes!) uses a huge tank of LPG to power his home cooker and central heating system as well as his modified car.

So no, I don't think it contains any additives specific to automotive use. This is of course why only certain engines can cope with it, and those constructed with less "over-engineering" will have a dramatically shortened life if run on it.

What I'm trying to learn therefore is if anybody knows whether the materials used in the Audi 2.7T cylinder heads are sufficiently "over engineered" that life expectancy will not be adversely affected, or whether I'll wind up with an expensive top-end rebuild after about 50,000 miles.

quickaudi:STFA

sincerely doubt anyone here has tried it

not as available here in states

Mudplugger

I guess that's at least partially down to a lack of incentive, because your petrol prices aren't as ridiculously over-inflated as ours! LPG is less highly taxed, seemingly because it's less harmful to the environment than either petrol or diesel.

Anyway, I think the the message is clear enough: LPG is substantially untested on this engine, meaning that I would effectively become the guinea-pig. With that in mind, I think I'll keep looking for a diesel Allroad.

Thanks,