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Feb 12, 2013 11:38:27 GMT
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As you can probably guess, a V8 in this day & age isn't the most economical of things to run and I'm considering fitting LPG so that I can actually think about using the car a lot more. The current set-up is a small V8 (less than 3 litres) with 2 x SU carbs. I have worked out that I can happily fit two seperate LPG (4 port) tanks in the back which will give me approx 100 to 120 litres of gas and still leave me a decent boot space, but it's the up-front engine side of things I really don't know about? I know that modern injection systems can run on single feed or sequential LPG set-ups but what about with carbs? Any info and pointers would be gratefully accepted. Also, if anyone has any 'useable' bits that would work for this type of set-up, I'm all ears.  Many thanks.  |
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Feb 12, 2013 12:10:46 GMT
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AFAIK, there isn't a option to convert non-EFI car to sequential gas injection anymore. There was a while ago - Will Holman of PPC had a sequential setup fitted to his K-jet Merc - but I think they've left the UK market.
Which leaves you with a standard evaporator-and-venturi system (as per the Landy). I'm sure you can run 2 mixer rings on a twin carb setup. It might be worth looking into a closed-loop system with a lambda sensor to get it running a bit better.
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Feb 12, 2013 13:36:46 GMT
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my advice would be get a omvl r90 vapouriser, they are simply the best and easiest to tune, run an open loop system with a venturi for each carb or one depeding on the air intake setup.
not sure what year landy your on about but if it has hardly any electrics u can simply use on off switches and relays to turn the gas on/off.
Dunno what kinda of fuel pump your running, if its electric can turn it off with a relay if manual you my need to convert to electric or use an electric shut off valve.
Id also get a wideband lambda and gauge so you can set it up spot on.
ive intalled a few second hand kits to my older cars and they have all been done for under £100 including buying new pipe, the newish poly pipe make it even easier too.
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Last Edit: Feb 12, 2013 13:39:36 GMT by damageandy
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tubbs
Part of things
Posts: 59
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Feb 12, 2013 14:17:26 GMT
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They run very well on twin mixers, the trick is to get a y power valve so you can set up both at once, two power valves is hugely tricky to get right. Even for me ! And ive been in the LPG trade 16 years now. As someone said omvl r90 is a good reducer, but they are a bit prone to 'squaking' as they get older. Not that you would hear it over the v8.
Obviously unless you could find and early efi manifold complete and the air flow meter and the ecu and loom etc. Then its pretty much a straight swap. You could run an injection system full group. The italian systems are the best at full group running. The polish systems (stag/kme) don't really support it.
Decades ago the first gen injection systems where stand alone. So you could use them on a carb engine as long as you put a throttle switch on. But all the systems now are piggy back from petrol injectors. So its far easier, and cheaper to fit mixers.
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Feb 12, 2013 14:30:06 GMT
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Just to clarify - this is NOT a Rover V8 (note the "under 3 litre" comment) - and there is no EFI option for this engine. The Landy reference was to one of his other vehicles which is already fitted with a basic mixer LPG setup.
The carbs on this engine do share an air filter, but the middle of the air filter seems to be the only point they do share - so not ideal for a mixer ring. Twin mixers it is by the sound of it.
Fuel pump is 'lectric.
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Feb 12, 2013 16:01:32 GMT
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Thanks for the comments guys. James is right, this is not for a Rover V8 and the confusion has come from (as James has said) the fact I run a Land Rover on a 3.9EFi with LPG. James, just to clarify, this particular engine has two seperate filters, so it's sounding very much like I'll have to fit twin mixers.  I guess I need to read up more about how these systems work, I seem to be getting more and more confused with vaporisers, reducers, power valves, mixers! I've just signed up to an LPG forum, but there seems to be lots of talk, but very little info in the way of guides/principles. I bet if I ask a question like I have here, I'll get the common response to 'newbies' of "use the search" even though I have and it got me even more confused!! I'll get there. I hope! |
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Mr S
Posted a lot
10-4 Good buddy.
Posts: 2,654
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Feb 12, 2013 16:15:30 GMT
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I'll see if I can dig out my old installation manual that I scanned in some time back when I LPGd my old W126 V8. It's got loads of useful information in it...
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Suzuki GSXR1000 K2
BMW R1150GS
BMW K1200RS
Chevy K5 Blazer
Chevy Suburban LT
Jaguar XKR
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Feb 12, 2013 16:18:59 GMT
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if your not bothered about having a rubbish lpg fuel gauge and switch, you could really simply wire it to a single switch to turn petrol off and gas on, using a 5pin relay.
basically it goes, Tank - solenoid/filter - vapouriser (eg omvl r90) - pipe with a power valve (basically a screw valve to control gas) - twin mixers/venturi.
personally i wouldnt bother with any closed loop lambda system, my experience is they are just curse word, id buy a lc-1 wideband instead thn you can see exactly whats happening all off the time.
Lpg forum is decent, they are some very knowledgeable chaps on it, once you get the basics its really simple just takes abit of reading, but well worth it.
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tubbs
Part of things
Posts: 59
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Feb 12, 2013 17:12:03 GMT
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You will find me over on the LPG forum. One of the members over there has a little site DIY-LPG.CO.UK. A good place for some background. And a reducer/vaporiser is the same thing by the way. Single point units are pretty simple. Liquid to the front. The reducer/vaporiser turns the liquid into a vapour and its then introduced through a mixer (or 2 in this case) into the engine. It's all done on vaccum. But the mixers are a Venturi. Similar to the burner rings on a gas hob. More suck from the engine the more gas is demanded from the reducer/vaporiser. It has a diapram in it. However it needs a restriction in the gas line to the mixers. That's the power valve. The reducer is just a carb really. It has an idle and main mix screw in simple terms.
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Feb 12, 2013 17:22:12 GMT
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BLOS lpg carbs get good reviews from owners (not just the bloke who sells them now) supposed to be pretty easy to set up. Mixer shape and size is critical to getting decent performance, take advice from someone who knows your engine if possible, ones that bolt straight onto SU's are available - don't just go for universal mixer rings you will be disappointed.
Oh and don't forget the 10 year test on the tanks as you'll not get the paperwork (if you are bothered about it) with an out of test tank - the tanks are marked with there date of manufacture and if appropriate the re-test date - i've never seen one that has been re-tested in the UK though...
Just remembered i've got to strip a closed loop kit off a jag xj40, it should all work with yours bar the mixers. PM me if you are interested and i'll let you know when its off
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Last Edit: Feb 12, 2013 17:29:11 GMT by dodgerover
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Feb 12, 2013 18:19:13 GMT
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I've probably got most if the bits you need for a twin carb set up...y
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Koos
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Feb 12, 2013 18:26:18 GMT
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Thanks for the help and advice so far everyone, Tubbs, I'll certainly be checking out the LPG Forum when I get chance. Hopefully I'll understand it all a bit more very soon. Mark, I'll give you a call after dinner if that's OK? (pizza covered in home made chilli tonight which is far more important than phonecalls, I'm sure you understand?) Dodgerover, I could be interested. I'm going to try and track down a similar car to take some measurements from so that know what tank sizes I can go up to. Thanks again everyone. |
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B-8-D
Posted a lot
down to one car!!
Posts: 4,038
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Feb 12, 2013 18:36:30 GMT
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i do love the baby hemi...
si
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Feb 12, 2013 18:45:32 GMT
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LPG is operating theory is dead simple really, if you can figure out how a carb works LPG is a doddle
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tubbs
Part of things
Posts: 59
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Feb 12, 2013 19:26:31 GMT
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Have a look at diy-lpg.co.uk. Its very good info. Dueltechuk.co.uk also has a heap of good info for beginners.
I'm currently in the process of writing a generic manual of installation for a gas injection system aimed at diy. See i started as a Diy'er myself back in 1996. So I'm always happy to support it. It just needs the right information to be available. The code of practice seems to be a secret entity. But it has to be adhered to if you want the install to pass inspection.
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Last Edit: Feb 12, 2013 19:33:10 GMT by tubbs
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Feb 12, 2013 19:49:04 GMT
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Don't know if it is still current but COP II used to be available on line, am pretty sure i still have a copy, from memory strictly speaking aren't all the cars with towbar mounted filling points in breach of one of its recommendations?
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tubbs
Part of things
Posts: 59
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Feb 12, 2013 20:08:50 GMT
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As long as they will withstand 500nm and are not lower than 200mm from the ground rear fillers are perfectly acceptable. And the 200 mm is only advisory and not mandatory.
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Feb 12, 2013 20:34:57 GMT
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Thanks Tubbs,
I've had a quick look through the DIY website and some of the info looks like it'll be quite helpful. I'll put a post up on the LPG Forum in a mo' just to say hello and introduce myself.
Fingers crossed I'll have some dimensions tomorrow that will help me start looking for the optimum sized tanks. Thanks again....
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Feb 12, 2013 21:12:38 GMT
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Sorry Tubbs, I thought it was towbar mounts, maybe rear bumper mountings? Well done for supporting DIY LPG though.
MM Remember tanks should only go to 80% fill, so a 100l tank will only contain 80l of LPG fill cuts off. Older tanks didn't have an 80% cut off and had a sullage? valve on them you used to have to open to vent/ determine when they were full, its highly unlikely you will come across one of these though.
You can (but shouldn't) rotate the tank slightly to get a higher level of fill, parking on a slope while filling will have similar results. The reasoning for the 80% cut off is to allow room for expansion should you fill the tank then park in the blazing sun all day. If this happened the tank should vent in a controlled manner (hence the gas tight box over the multivalve). In practise with a V8 the journey home from the gas station would probably get you down to 80% anyway...
If you have 2 tanks you can use the cut off solenoids seperately at the tank end to allow you to run one tank as a reserve which is handy if you decide to go gas only.
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Thanks for the help and advice so far everyone, Tubbs, I'll certainly be checking out the LPG Forum when I get chance. Hopefully I'll understand it all a bit more very soon. Mark, I'll give you a call after dinner if that's OK? (pizza covered in home made chilli tonight which is far more important than phonecalls, I'm sure you understand?) Dodgerover, I could be interested. I'm going to try and track down a similar car to take some measurements from so that know what tank sizes I can go up to. Thanks again everyone. You better save me some of that pizza! :-) |
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Koos
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