DIY LPG kit on a DIY turbo 2 1/4 diesel!

For you LPG gurus out there I've got a few more Qs! I've now got a mixer, vaporiser and donut tank from a 1.4 Dawoo thing for my DIY diesel project. Probably a good time to ask about regulations for LPG systems. I'm sure I've heard they need to be checked and certificated bit like the Corgie registration system. Is this going to be a problem on a DIY system or isn't anybody going to be any the wiser?

I'll have to get some a good length of copper pipe as the original filler to tank and tank to vaporiser pipe had to be cut. Any recommended places? I could just sleeve it with high pressure rubber pipe to try it tho.. What sort of pressure is the regulator on the tank set to? I think I better use copper pipe with compression fittings to fill the tank!!

The vaporiser had two screws on it as far as I can see. One is marked "Idle" and the other isn't marked at all. Any pointers what these do? Also, between the mixer and vaporiser is a solenoid valve that must map the flow to the engine requirements, it was after all connected to a "lambda control unit". I'll just remove this and blank off the hole. But there is also a big brass screw in the same housing, looks like its perhaps for course manual flow control. I presume this is used to set the max flow?

Does the vaporiser work like a "demand valve"? So a slight depression from the venturie in the mixer causes the gaseous LPG to flow, with the higher the depression the more LPG. Basically like a simple carboreta? Thanks! Toby

Not until it all goes pear-shaped and your insurance get an inspection done!

If you use anything other than the correct copper pipe and olives, then assuming you live within the northern hemisphere, please emigrate to the southern one!!! You cannot use anything other than the correct kit or you are driving a mobile time-bomb.

The one that isn't marked is the tension screw, it effectively controls the rate of opening of the vapouriser in response to manifold depression.

Yes, remove the whole thing and fit the correct manual adjusting valve, don't muck about with things, the slightest leak could cause a build-up of gas within your engine bay, with dire consequences.

Yes. May I politely suggest that you go and get someone who knows what they are doing to at least guide and assist you, as you give me the impression that you haven't got a clue about LPG systems and I really fear for your safety - LPG is dangerous stuff if not handled correctly. Badger.

On or around Fri, 4 Feb 2005 17:53:26 -0000, "TVS" enlightened us thusly:

didn't realise you were looking at a diesel, be careful you don't get a runaway. If you get the fuel wrong, it can...

filler-to-tank can be flexible hose, with suitable fittings (which are crimped on by the manufacturer) or copper (summat like 10mm OD) with flared ends or olives, depending on the types of valve. Tank-to-vapouriser is normally 6mm OD copper.

The pressures can go up to close to 200 psi, though more normally it's about

100, so sleeving it with hose is not recommended.

You presume correctly. What make of vapouriser? The screw marked "idle" may adjust a slow fixed LPG supply, or it may adjust spring tension in the vapouriser. The other screw may do the spring tension, or it might be a drain plug if it's at the bottom, for draining heavy ends.

pretty much, yeah. something like a scuba thing, I believe. more airflow in the inlet tract makes more depression in the mixer, which moves the diaphragm in the vapouriser, letting more gas through.

You'll be well advised to start off with it set to deliver as little gas as possible, for a diesel application.

Are you trying to get more power, or cheaper running? If the former, you want a small (ish) amount of gas a t high power settings only. If the latter, then you want more gas, but you turn the diesel pump down so it delivers less fuel.

All in all in my opinion it sounds like a recipe for disaster

May I politely inform you than I happen to be a fully qualified Mechanical Engineer and am also an experienced Mechanic. I do appreciate your obviously strong concerns for safety but I can't help but feel you should reserve your hasty and overly critical judgements in a public forum until you know all the facts. No where have I suggested that I will be driving around with a setup of this nature. This is purely experimental for building up a performance map from testing on an engine dynamometer. Perhaps I should have stated this in my post but I was asking for technical information and wasn't expecting my competence to be in questioned. Toby

Which was why I "politely suggested", so please get off your high horse. My judgement was neither hasty nor overly critical, based on your comments. If you don't like the answers, don't ask the questions in a public forum in the first place. If you are indeed as skilled as you say then you should be aware of the dangers of what you suggested re. flexible hose for a liquid feed. It was that comment that worried me, hence my response. FWIW, your comments re. certification led me (and no doubt others) to believe you were indeed intending this set-up for road use. As I said, your post gave the impression (based on the questions that you asked) that you knew little or nothing about LPG systems, hence my suggestion to seek guidance or assistance. I do not think that was an unreasonable suggestion. However, to avoid any further "snappy" replies, I for one will not respond to you again in the future. Badger.

I feel you may have both been a tad snappy there!!

;~)

Nige

-- Subaru WRX (The Bitch)

Series 3 Landrover 88" (Albert)

"If you tolerate this then your children will be next"

I was about to reply to my own post appologising for beeing perhaps a bit out of order in my reply but I strongley recent your sugestion that I'm on my "high horse". Certification is my consern for when I fit a setup to my landrover and I wasn't clear that my "throw it together" aproach for testing wasn't for vheicle use. I still feel your reply was overly scorn full and patronising when others have answered my questions very helpfully and freindly. If you ever ask a question hear I wouldn't be childish and willl answer as fully and helpfully as I can. Toby

Thinking about using oxyaccetaline type pipe with a barbs soldered onto the

8mm stuff so should be ok between the tank and the vaporiser then. The problem will be filling the tank as I don't think it would look very good with it all siting loose in the back of the landy at the filling station! Besides which the stiff copper pipe between the filler and tank would be too risky all unsuported in the back. Do need to fill the tank some how whilst its in the development stage tho... Humm.

The Vaporiser is made by err.. is it Mcemme? Its made in Italy, can't quite make out the first two letters! I've conected it up to a airline and turned the pressure down to 30psi. Yep, the idle screw seems to be a VERY course adustment of the base flow rate. There is a plug on the bottom, but this looks like an adustment screw..

I did put my lips around the pipe to the mixer and sucked (Oh matron!) and it did let more compresed air thought it. Heheh. So yep, that proves that one!

From what I can find, around 8% LPG is suposed to give the best ecconimy with around 30-40% giving maxumum power. I'll be able to tell exactly from testing, but if I set it up for around 75-80hp maximum (save blowing the engine to pices!) and aim for best econimy at cruse. I'm thinking about trying the mixer in a simple drawthough setup first between the airfilter and the turbo but am wondering if I should try and controle the flow of LPG from boost presure and/or RPM. Thanks! Toby

On or around Fri, 4 Feb 2005 21:31:34 -0000, "TVS" enlightened us thusly:

well, it did come over like that. And I certainly from what you've been asking gained the impression you were doing a conversion to go on the road. There are indeed people who would put together a dangerous lash-up and mores the pity, some of them are in the trade; luckily not many.

as to the rest, well a) you never said you were an engineer (or if you did I missed it), or what kind, and b) What you said made Badger (and indeed me) think that you didn't know what you were doing and were about to create a dangerous bodge. If you want to read "respectfully suggest" as a criticism, rather than as what it says, then that's up to you.

I've seen Badger's postings for some considerable time, and I don't agree. If he'd thought you were a prat, he'd probably have said so in so many words.

so both of you come and shake hands and start afresh. I agree with Nige, you're both being a bit hasty.

On or around Fri, 4 Feb 2005 21:59:03 -0000, "TVS" enlightened us thusly:

If I were you I'd put the mixer between the turbo and the engine. You don't want flammable gas in a hot turbo... would really want in intercooler as well, I should think (which improves the efficiency anyway, so you go

filter > turbo > intercooler > mixer > engine.

Make absolutely sure if you do a temporary liquid propane connection that it'll take the pressure. I'd want to see at least 200psi-proof, I reckon. If you dump liquid gas from a slip pipe, you get *lots* of vapour - something like 250 times the volume, I believe, some such silly-sounding figure.

What kind of valve on the tank? is it a single-hole thing with a multi-valve in, or a 4-holer? If the latter, you can probably get a flexible filler hose. Mind, if the valve's wrong, you'd need the tank empty to change it. Is the tank actually empty? it's not easy to empty them. I have a spare one in the yard which still has gas in it; might get around to doing something with it one day...

This is always a very freindly and helpfull newsgroup and I woudln't want to do anything to change that. I think we have probably got of on the wrong foot, so to speak, and this is just a clash of personalities and not a personal thing as I might have taken it to be. I hope Badger will meet me half way and start afresh. Sorry! Toby

Mebbie you sould instal a spel tsjekker

It rilly looks naf wen an engeneer kant spel.

Peter R.

Fair enough, sorry. Matter forgotten. Badger.

On or around Sat, 05 Feb 2005 09:13:43 +0100, Peter R. enlightened us thusly:

yebbut, engineers CBA to learn to trype prperly.

I can spell fine, it's me fingers that can't.

On or around Fri, 04 Feb 2005 22:34:55 +0000, Austin Shackles enlightened us thusly:

slip?? that was meant to be split.

buggrit, must learn to type properly one day.

S'metric keyboards innit, don't work with Imperial digits

Totally unsuitable, the pipe from the tank to the vaporiser is unregulated, full pressure liquid. Oxy & Acetylene pipes are for regulated gas only.

I think Austin is right from the safety angle, you don't really want the whole intake between turbo compressor and valve full of an explosive mix, but air:propane mixes will only support a flame near stoich and op is talking about fumigating in the 8% and 40% region of the energy in (the balance still made up by diesel), as diesels run well lean of stoich up to over fueling (black smoke in exhaust) I'll bet a backfire could not support an explosion, never tried it though. The only fumigation with propane I did was on a 6cyl direct injection ford tractor engine, it certainly cleaned up the exhaust visibly at idle and put the revs up.

The other thing is under the above scenario the pressure from the turbo compressor will need compensating at the diaphragm, as it varies with power output.

As to whether it can give better economy I'd like to be convinced. You can get better economy by buying a cheaper fuel or increasing combustion efficiency (all other things in the engine being equal). I cannot see more than a few parts of a % available by better combustion but would be pleased to hear it could. LPG contains 68% of diesel at our local pumps per unit of heat energy and costs half, so at full fueling there is potential for a 40% saving, at 40% substitution this drops to 16% and at 8% to 3.2%.

The power gain moving from exav of 1.2 to stoich is likely to be 20%.

A rough calculation gives me a vapour to liquid:volume ratio of ~400:1 at 0C for propane.

AJH