LPG Conversion

[Jon06Vrs]

Any advice on whether an LPG conversion is a good idea on my 2.0lt VRS TFSI haven't had any experience with this but am looking for any feedback if anyone has had this done usual questions, is it cost effective any performance issues? valve compression an issue or injectors? any useful advice would be greatly appreciated

[M12MKD]

might be worth having a quick read on this website

[Jon06Vrs]

I asked about converting mym wife's 1.6 Petrol Seat Leon to LPG, and was advised by my trusted mechanic not to do it. He works at a local Mercedes dealer, and has experience of a whole fleet of petrol Mercs being converted, and every single one that was done having to have the cylinder head replaced due to excessive heat from the combustion.

Anyway, for the cost of the conversion, you'd have to do a hell of a lot of miles to make it even pay for itself, before you start saving anything. If you want to save money, but a diesel and have it remapped.

There could also be warranty issues if you have a conversion done.

Mike

car is out of warranty so no issues there, the little research I have done shows that certain types of engine need something added to lubricated the valves as they are a certain type of alloy which gets damaged over time, have just had a quote of 1650 for a conversion which includes a courtesy car for the week, based on my current fuel costs I could save roughly 1300 a year which means it pays for itself in just over 12 months, the only concern is additional servicing costs for the gas system as it seems I may need to have 2 services a year 1 on the car and 1 on the LPG system at 300£

[andyvee]

Having run a LPG converted (Zavoli system) 3.2 V6 4x4 for 4 years before switching to a diesel I can give you the benefit of my experiences.

The only kit to go for on a turbo car is a Prins kit. Don't bother with the cheaper AEB based Italian kits or any Turkish rubbish. A Prins kit should cost the best part of £2K.

Now LPG is a rather silly price (I seem to remember seeing about 80p a litre) it will take a long time to recoup the conversion costs. When I had mine done LPG was 35p a litre, and unleaded about 85p.

The fuel duty on LPG is set to increase gradually over the next few years, so the gap in price will narrow.

You will get about 20% less mpg on LPG, don't believe the hype about it only being 10%.

Your hands will stink of the stenching agent they put in the gas after every time you fill up.

You will lose your spare wheel.

LPG is good on a turbo car - a lot of the Zafira VXR and GSi owners run it at higher boost and compression as it has a higher octane rating than unleaded, but a lower calorific value.

If you are going to keep the car for 20K plus more miles then consider it.

You will find it hard to sell, only a handful of LPG diehards will be interested in a couple of years time.

Any stories of damaged cylinder heads etc mean it wasn't set up correctly - you need valve lube if the head suffers from valve seat recession. Yes, combustion chamber temperatures are higher, but changing to a NGK LPG spark plug will help. You also need make sure the plugs are running at a smaller gap than standard as LPG is 'dry' and a little harder to ignite.

Having done it for 4 years I wouldn't bother now LPG is so pricey. When it was just less than 50% the price of unleaded it was worthwhile. Can't see the point now.

You will probably get a 80L tank maximum in the spare wheel well. As the tanks only fill to 80% to allow for expansion, that is 64L of gas, or 14 gallons. So, if you get 35mpg now, that is 28mpg on LPG. So the range on your tank will be approx 390 miles. If you can only get a 60L tank in, your rnage is reduced to 290 miles. It can still be a pain finding places to fill up, and motorway services charge an absolute premium above the current market rate, further reducing your savings.

The annual service on a LPG installation consists of the gas phase filter being changed (£10) and a leak check, as well as checking the LPG ECU hasn't logged any faults.

If you go ahead, ask if they are removing your inlet manifold or drilling it in situ. If they aren't removing it, walk away. How would you like the swarf from your inlet manifold being drilled and tapped for the LPG injector nozzles ending up in the combustion chamber???

[Jon06Vrs]

Having run a LPG converted (Zavoli system) 3.2 V6 4x4 for 4 years before switching to a diesel I can give you the benefit of my experiences.

The only kit to go for on a turbo car is a Prins kit. Don't bother with the cheaper AEB based Italian kits or any Turkish rubbish. A Prins kit should cost the best part of £2K.

Now LPG is a rather silly price (I seem to remember seeing about 80p a litre) it will take a long time to recoup the conversion costs. When I had mine done LPG was 35p a litre, and unleaded about 85p.

The fuel duty on LPG is set to increase gradually over the next few years, so the gap in price will narrow.

You will get about 20% less mpg on LPG, don't believe the hype about it only being 10%.

Your hands will stink of the stenching agent they put in the gas after every time you fill up.

You will lose your spare wheel.

LPG is good on a turbo car - a lot of the Zafira VXR and GSi owners run it at higher boost and compression as it has a higher octane rating than unleaded, but a lower calorific value.

If you are going to keep the car for 20K plus more miles then consider it.

You will find it hard to sell, only a handful of LPG diehards will be interested in a couple of years time.

Any stories of damaged cylinder heads etc mean it wasn't set up correctly - you need valve lube if the head suffers from valve seat recession. Yes, combustion chamber temperatures are higher, but changing to a NGK LPG spark plug will help. You also need make sure the plugs are running at a smaller gap than standard as LPG is 'dry' and a little harder to ignite.

Having done it for 4 years I wouldn't bother now LPG is so pricey. When it was just less than 50% the price of unleaded it was worthwhile. Can't see the point now.

You will probably get a 80L tank maximum in the spare wheel well. As the tanks only fill to 80% to allow for expansion, that is 64L of gas, or 14 gallons. So, if you get 35mpg now, that is 28mpg on LPG. So the range on your tank will be approx 390 miles. If you can only get a 60L tank in, your rnage is reduced to 290 miles. It can still be a pain finding places to fill up, and motorway services charge an absolute premium above the current market rate, further reducing your savings.

The annual service on a LPG installation consists of the gas phase filter being changed (£10) and a leak check, as well as checking the LPG ECU hasn't logged any faults.

If you go ahead, ask if they are removing your inlet manifold or drilling it in situ. If they aren't removing it, walk away. How would you like the swarf from your inlet manifold being drilled and tapped for the LPG injector nozzles ending up in the combustion chamber???

Wow, i think that solves it for me then thanks alot, current price i found locally is 82.9 on lpg given the 2k conversion and the 20% drop in fuel economy,and i think i would be looking at a 53ltr tank in the wheel well this will only save me about 4p-ltr so, will give the guy at the garage one last chance to convince me, but otherwise its not a good idea i dont think!

Cheers andyvee you have provided a very concise and conclusive summary on the subject.

[andyvee]

When I was driving a 210bhp 3.2 V6 4x4 LPG was the best thing since sliced bread at less than 60p a litre. As soon as the price started creeping up it made it more difficult to justify. 24mpg on petrol, 20mpg on LPG!!!!

One thing I did notice, when petrol prices started to fall again, it took a while for LPG to follow suit. Probably to do with the lower demand and the fact that garages probably only refill the tank every few weeks.

A properly set up LPG system is a joy to drive, the car seems to run smoother and quieter. I did almost 80K miles on mainly LPG with very little in the way of issues. The industry has a bad reputation as there are some cowboy fitters out there, but if you get the best kit fitted by a professional it will be trouble free. It costs more though! If you shop around you can probably get a cheap kit fitted by a cheap outfit for not much over a grand, but you get what you pay for.

The AEB kits are the next best to the Prins - Zavoli are quite good but apparently a bit of a bitch to set up on turbo cars. The problem once you get over 50bhp per cylinder is getting enough gas in there quickly enough - that means big injector nozzles for more flow. This then causes an issue at idle and low revs - the injectors can't meter the fuel accurately at really short opening times on large nozzles. This causes uneven idling due to mixture fluctuation, and your petrol ECU can start adjusting long term fuel trims to compensate as most of the time it will be running rich. This means when you run on petrol after prolonged use on LPG the fuel trims are miles out, you are running too lean for a while until it compensates back again.

Always odd on really cold days to see what is basically steam coming out of the exhaust as it runs so cleanly. My car read 0 for everything on its MoTs when presented running on gas! And that was at 150K miles, 80K on gas.