The Toyota Landcruiser Owners Club

[The Silver Bear]

I am about to convert my V8 to LPG. Cost seems pretty standard and have been offered a good deal incl free loan car and 2 year warranty fropm London Petroleum Gas Co. Does anyone have any experience of this company before I hand over my beloved beast? Also, have read in one or two other forums about possible downsides to LPG conversion e.g reduced engine life.  Is there anything that should make me change my mind?
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Amazon 4.7 VX

[Google]

[revrev]

My understanding is that an LPG converted engine will have a longer life. LPG burns very cleanly so there are negligible carbon deposits so oil changes can be more infrequent as well.

[dr ali]

hi, i have been quoted 1800 at rage motors in monmouth, any one with any experience with this garage.
ali

[bushburywolf]

i believe they burn hotter , therefore valve seals and compression  rings in the cylinders and  head could be affected ..that's what a mechanic told me once ..but he was one of the biggest lying barstewards i have ever met, telling me he serviced the car before i took delivery ..*beep* see prevoius post of mine on "dirty tricks"
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1999 Amazon Auto  VX 4.2 TD Active

[Wandering Willy]

The problem with LPG is the speed at which it burns. Hydrogen burns quickest of all the gases and LPG is a lot slower. So...

If you keep the engine speed low, the time available for the fuel to burn (whatever it is) is relatively long. When the engine speeds up, the time goes down. Eventually, you reach a point at which the LPG is still burning as it leave the cylinder via the exhaust valve. This overheats the valve and manifold. It also means that the contents of the cylinder are still very hot along with the cylinder walls, the top of the piston and the cylinder head. This can overload the cooling system and ignite the new fuel/air mixture as it arrives leading to destructive detonation. This sets a limit to top end performance.

The plus factors are that the fuel should arrive as a gas which mixes 'perfectly' with the air resulting in a very clean burn so no soot and much less pollution. The cylinders stay clean so no coking and no dirty oil. Also, LPG has a much higher octane rating than any petrol. It's about 118 compared to 93-95 for unleaded. Obviously most engines don't take advantage of this.

The early LPG conversions with fuel injected engines suffered as the knock detector let the ignition advance round the clock to something like 30deg BTDC and the converting garage had to set a limit to the amount of ignition advance which the engine could achieve to avoid this happening.

In theory - if the engine was strong enough - the compression ration could be raised to something like 13:1 but then the engine could only run only LPG. While this sounds a bit pointless, such an engine would have a much better efficiency (nearer to a diesel engine) and more power. BUT you would need a stronger engine to cope.

In a perfect world (ha!), cars would be offered with small low revving high compression engines running only on LPG and producing little or no pollution without the need for catalytic converters. Remember that the price for a cleaner exhaust is a 5% performance/efficiency loss because of the catalytic converter and a similar loss because of the drop in octane rating when the lead anti-knock compound was removed. So, instead of pollution we add to the production of CO2 and destroy the planet that way!

Rant over, I'm getting off-topic so I'll stop.

Willy

[bushburywolf]

actually willy that was quite educational ..thanks
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1999 Amazon Auto  VX 4.2 TD Active

[Wandering Willy]

Sorry for the brain dump. I get a bit overheated re LPG and it's current use.

It's one of the by-products of the North Sea oil and gas fields that gets used by the power generation companies. They claim the credit for it's low pollution and low CO2 output but it's a crying shame when it is a super vehicle fuel being used to replace the bottom end of the crude (what's left over after petrol and diesel are removed) or coal to fire power stations.

My comments about catalytic converters (fine for California or downtown Tokyo) and low octane petrol come into the same category. I trained as a mechanical engineer and get depressed when I hear 'politicians' start spouting on about saving the planet. They just don't have the technical knowledge and at least half what they propose is *beep* when you look at it in detail.

Regarding LC's and LPG, it makes a good combination if you can get the right bits installed properly. For example you need a big tank as you will use more than petrol (it's cheaper and the consumption is 10% higher). Also, you can only fill the tank about 80% full. So you probably need a tank capacity (2 smaller tanks?) of around 120 litres. The kit to supply fuel to the engine is pretty sophisticated and a good supplier can advise what will give the best results for any particular engine model. I had some dealings with Tinley Tech and they seem to have as good a range as anyone and can advise. They don't install but can suggest installers who know their stuff (they are importers). This is their web site:-

http://www.tinleytech.co.uk/home.html

If you want to see what can be done with an LPG installation, look at the pages here, e.g. the one on refinements. There are other companies supplying this stuff but I know this company is pretty good. I can't speak about the others. When I was looking for my LC, I went there to see what I should use if I got a petrol engined car. Eventually I got a diesel amazon so didn't need the LPG kit but gained a bit of knowledge along the way.

I hope you find my comments useful

Willy

[bushburywolf]

i have a diesel LC too but it is certainly is useful information ... thanks again Willy ..i know of at least one member who may be interested...SIMON .....are you looking  
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1999 Amazon Auto  VX 4.2 TD Active

[adrianlp]

Willy has put some really interesting stuff down here. The LPG world is murky and conversion experience and subsequent track records of different cars is sketchy to say the least. Convertors are not overwhelmingly helpful with facts like "on lpg your valve seatings will suffer and one day you'll just lose compression  and need an engine rebuild".

Nevertheless my mechanic had a look at my Passat recently and said "on lpg your valve seatings have suffered and you've lost compression. You'll need an engine rebuild." So there we are.

However i am dead keen to not let my amazon go the same way. I've done 60-70k on lpg now and it's a trooper. But how can I mitigate the issues with lpg and keep it going another 50-70k?

THere's been talk of lube devices but then are there issues with catalytics etc with this mist of oil swirling about? As I have posted elsewhere on this great forum my Toyota has now started missing a beat or three in the same way that the passat did. I have not noticed a loss of power but then this is a beast of an engine to which the loss of half a cylinder is a mere scratch. I will have to face the music and find out what's happened but whatever I discover will I expect be extremely useful to many guys here who have or are considering a conversion.

Willy I like the idea of a car that only runs lpg if it does what you say. I'll just need to plan those M4/M5 journeys a little more carefully.

[Wandering Willy]

Thanks for the feedback. It's always good to have some firsthand experience.

The best lubricant for LPG is supposed top be 'flashlube'. You can buy the kits and the stuff to use in them. Just search for flashlube in google or similar and go from there.

Keep the news coming.

Good luck with your car.

Willy