Any one running lpg on any of the direct injection petrol cars?  especially the V6! Some of the new systems inject lpg still as liquid through the existing injectors

 

 

 

http://www.environmentallyfriendlycar.co.uk/index.php/gas-conversions/97-petrol-engines-and-gas-conversion/lpg-autogas-and-direct-injection-engines/118-direct-injection-petrol-engines-and-liquid-lpg-injection

LPG is a hated issue here for some reason, at 45p/ltr (with slightly lower MPG it must be said) id jump at it, Ive seen a new system that uses 90% gas and 10% unleaded and avoids valve burning issues, or you need valve oiling, most LPG fitted vehicles on Ebay are big petrol 4x4's so it must be good.....

LPG is a hated issue here for some reason, at 45p/ltr (with slightly lower MPG it must be said) id jump at it, Ive seen a new system that uses 90% gas and 10% unleaded and avoids valve burning issues, or you need valve oiling, most LPG fitted vehicles on Ebay are big petrol 4x4's so it must be good.....

 

I think the latest liquid injection gets round the valve burning issue in some way, not sure how though....

I think the latest liquid injection gets round the valve burning issue in some way, not sure how though....

 

It is the latest lpg systems that use existing direct injection that have caught my attention.

 

Valve seat recession may occur on "port injection" cars for a few reasons

1) The lack of the cooling effect of petrol passing by the valves

2) Hotter combustion

3) Modern lightweight cylinder heads and valves made of putty (Some older type engines fine - eg earlier Chrysler Jeep 6 cylinder)

All this causes a sort of "welding" type problem that eats away at valves/seats

 

Saying that I've got a friend a work with a 190,000 mile Mondeo that has not suffered this! On every oil change the oil drained is the same colour as the oil that goes into it

 

However with direct injection injection engines

1) You don't have the cooling effect of fuel (petrol) anyway - so cylinder heads/valves are more robust (eg tsi sodium filled)

2) You still have hotter lpg combustion but with direct injection you have the cooling effect of liquid gas evaporating (latent heat of evaporation etc) just below the valves - this may also help with the valve carboning up problem that some direct injections have (NB EA888 engine now uses port and direct injection)

 

That's why the liquid direct injection system caught my attention  - also runs on lpg from starting

 

Valve oiling can cause other problems - eg catalyst

 

 

Not sure it would be advisable on my 1.4 as you do loose some power as lpg has a lower calorific value and to be honest the economy is already great anyway!

 

Would make a V6 affordable though!    

Edited 11 October, 201510 yr by bigjohn

I have run lpg on a Mercedes 230, Opel Omega, and Chrysler Stratus over a 10 year period and never had a moments problem with the engines. I had a 1988 Jaguar XJ6 but this could not be converted as it did not have the hardened valve seats. I think you will find that most engines produced in the last 15-20 years will have the hardened valve seats and conversion is possible. The gas system has stop **** to isloate all fuel going to the engine which can be placed in a not so obvious place and you then have a good anti theft device. I never really notice a fall off in performance. Should I ever change my diesel I would seriously consided lpg again.

I have run lpg on a Mercedes 230, Opel Omega, and Chrysler Stratus over a 10 year period and never had a moments problem with the engines. I had a 1988 Jaguar XJ6 but this could not be converted as it did not have the hardened valve seats. I think you will find that most engines produced in the last 15-20 years will have the hardened valve seats and conversion is possible. The gas system has stop **** to isloate all fuel going to the engine which can be placed in a not so obvious place and you then have a good anti theft device. I never really notice a fall off in performance. Should I ever change my diesel I would seriously consided lpg again.

Skoda also sold an official lpg mkII Octavia in some other European countries