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Discussion Starter · #1 ·
I have just found this forum and am hoping someone can give me some advise or personal experiences with LPG conversions. I live in Syney Australia and I own a 1996 Disco 3.9L but the fuel consumption is burning a massive hole in my pocket. I have just recently started researching LPG conversion (running both Unleaded and LPG fuels). Can anyone tell me if this common for Disco? any common problems that discos have from running duel fuels? things I should weary of? will this help reduce valve sticking? I'm all ears for any comments/suggestions/personal experiences.

Thanks :dunno:
 

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As I understand it, LPG conversions can only be caried out on petrol models, although I did rad about someone testing out a diesel version....

The main problem I've heard of is thet the cylinder heads can run hotter causing the engine to over heat, depends how good the fitter is. You may also get a loss in performance.

Prices in the uk sem to range from £300 diy kits to over £1000 for profesionals.

Also you need somewhere to put the LPG tank.
 

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Lpg

Both my series 1 V8 and my rangie run on LPG its the best money I have ever spent,halved my fuel costs the kit cost me 400 quid and paid for itself in 3 months I have had no bother in the 3 years ive ran it the oil is still golden after 3 years.

I have had no problems with over heating,it runs quieter I cant really think of any negatives maybe perhaps the loss of boot space due to the tank,but there are tanks that will fit where the fuel tank is situated so this is no longer a problem.

The Disco will love LPG :clap: .

Dont buy an over complicated kit buy the simplest one as its less to go wrong this normally means its cheap to :)

Cheers ONz
 

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Discussion Starter · #4 ·
Thanx

thanks for the replies.

Onslow, was the LPG a DIY kit and did you install? In Aussie we can't do that, all regulated. Do you need to run the engine on petrol every now and again? how often do you do this? Is it to keep the petrol lines "alive & kicking"

FYI - I did a little researching today about LPG's

*Tank Size
*Tank Location
*Starting with LPG - may cause backfires (if ignition system not working right/pump too much gas at start up) this can blow the air flow sensor.
*10-15kw of power loss
* Can help eliminate valve sticking which is notorious on series 1's (nothing a really good fang around the block doesn't fix 9/10 times)
*need to run on petrol once every 1000km
 

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Hi there,

Back fires normally occur when the mixture is over lean, not with too much gas. I always start on gas, and have never experienced back fire in this situation. In my experience, back fire occurs when changing over from petrol to gas in an efi motor when the petrol is switched off at the same time as the gas is switched on. To get over this, a small lag of up to about a second is built in so that the gas is turned on before the petrol is cut off, thus inducing a rich mixture. My original early efi conversion suffered from this, and blew apart a couple of air flow meters of the flapper type as fitted to the 3.5 engines. For a while I ran with the afm with the bottom plate held on with spring clamps so that blow backs would just blow the bottom off rather than blow the flap. This worked fine on petrol too! After introducing the time lag, no more blow backs were experienced. When starting, the engine is primed with gas by turning ignition on and off a couple of times before starting. (When ignition is turned on, the gas solenoid opens, and if the engine is not sensed to be running from the ignition circuit, cuts off again after a couple of seconds. So do this a couple of times to flood the engine with gas).

I experienced one blow back on my 3.9 SE, but this was due to the ignition king lead having worked loose. The air flow meter on the 3.9 and later engines are hot wire type and do not blow apart like the flapper type. On mine, it blew the connecting hose from the afm to the plemum apart but the afm was fine!

You get a slight power loss with lpg, but that is if you keep the timing as for petrol. Timing is set for your octane rating and with petrol in the uk it is 95, whereas lpg is more like 100. Therefore to get the most out of lpg you need to advance the timing 2 or 3 degrees, but that means that your petrol running might be a bit "pinky". There are timing devices available to get over this, but to all intents, you hardly notice the difference.

Engines do seem to run smoother on gas, and cleaner. There is no need to run on petrol ever again, except to keep the pump running and to change the petrol over so that it doesn't go off. I have had the same quarter tank of petrol in mine for three years now though and it is still good.

The need to run on petrol may on a series engine, be due to the unleaded nature of gas. Series engines were for leaded petrol and don't like unleaded fuel. I don't know how you get on in Countries which haven't used lead for years. We now use a lead substitute.

All the V8's are fine with unleaded fuels anyway, and the 3.9 Disco will be absolutely perfect on gas. Do as Onslow says and get the simplest kit you can installed. There will be less to go wrong that way.
 

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Lpg

My 94 disco had a 90/100 ltr gas tank behind the back seat, about 350ks
per tank, which is better than the 300 from the fuel tank these figures are
not off road.

The biggest thing to remember is to leave your foot offf the go pedal when
starting otherwise your bonnet may take on a different shape, no probs
starting you may have to change plugs and leads.


td5/v8 :
 

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Just wondering guy's can you hook these systems up to su type carbs and also would there be any troubles running straight gas or is it better to run gas and fuel


Adam :beer:
 

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Regarding plugs, it is a good idea to have new plugs, but this is tied up with the lpg mixture's reduced conductivity compared with petrol mixture. Hence if you have an efi engine with the plugs gapped at 35 thou. then reduce the gap to 25 thou for a better spark. This is the same reason for why your leads need to be in tip top shape. If you haven't replaced yours ever, now is a good time to do it, and with a good quality set, like a genuine parts set which is only about £25, (sorry chaps, don't know about the rest of the world, but the genuine set does fit properly!). That goes for the distributor cap too. The genuine one is better than a good many after market ones.


Re SU carbs; yes they are admirably suited. You need a split supply pipe from the evaporator which feeds a mixer located in each of the inlet pipes from the air cleaner to the carbs. The operation is not quite so straight forward as on an efi system as to change over from petrol to gas, you firstly have to switch off the petrol pump, then let the engine run until it coughs or stalls, then switch the gas on and restart on gas. Obviously you can't just switch over to gas straight away as you will have gas and petrol mixture in the cylinders which won't burn and the engine will stop.

Therefore you do not start on petrol and change over to gas as a matter of course. You always start on gas as a matter of course if gas is what you are using, and you won't need to use petrol ever again.

Also with SU's, or Strombergs, you ideally need a vacuum piston lifting facility which involves a tapping in the dashpot chamber to connect to inlet vacuum via a solenoid which cuts in when the gas is on. This lifts the pistons out of the way and prevents them from going up and down as they normally do. This is not a necessity for running on gas, but is desirable as the pistons and jet needles are not wetted with fuel as they normally are and can wear out as a consequence. There has been some suggestion that rubber seals can dry out also if petrol is never used, resulting in flooding carbs when you put petrol throught them again, but you may or may not experience this, certainly if yours are in good condition, I would not worry too much.

When changing back from gas to petrol you have to switch the gas off and the petrol on, and wait for the float chambers to fill before starting. Otherwise, no problems.

In practice all these switching operations are undertaken with one switch, as on efi motors, but with three positions, petrol, off, gas. Use the off position when purging the system of petrol before switching to gas after the engine stalls.
 

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The idea of running on petrol every so often is to keep the gaskets and seals in the carb wetted every so often. They can dry out and then leak just when you need petrol and have run out of gas! I just switch over to petrol for a couple of miles every week or so (S1 2.25 Solex carb). Dad hasn't used petrol for over a year but was still fine when he had to switch (S2A 2.25 Weber carb)!
I always start on LPG without problems - never had backfires either!
 
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