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

On or around Sat, 5 Feb 2005 11:36:39 +0000 (UTC), "SimonJ" enlightened us thusly:

dunno what pressure they take, though. I expect they're good for at least

50psi.

I've been reading this and your other posts in this thread. You may be a mechanical engineer, but what you are firts and formost is a danger to yourself and your environment. Cease and desist. You have NO inkling of what you are doing.

Peter R, who will nut be entering the UK untill he reads of the explosion.

On or around Sat, 05 Feb 2005 17:18:42 +0100, Peter R. enlightened us thusly:

now be fair, he's not actually *done* all this. He asked first, which is sensible. And I can see the point in a temporary rig for testing, if you don't know whether it'll work.

BOOM!!!!!!!!!!!!!!!!

There you go :O) safe

Do you know anything about parachutes? No! Do you know anything about fitting LPG systems?

Yes but you need to amortise the cost of conversion over a much lower saving than a petrol to lpg conversion for probably the same cost.

Yes I believe it is a simple venturi when the pressure at the mixer is set just about atmospheric.

But the suck at the venturi is proportional to the change in velocity of the air flow either side of it, and is probably measured in fractions of an inch of water gauge, the boost from the turbo will be from atmospheric up to maybe 1 atmosphere (30 foot water gauge) when the waste gate blows off. So for the diaphragm to be able to supply the vapour to the venturi at just about inlet manifold pressure, so the mix can be metered proportional to the air flow, both sides of the diaphragm would need to see turbo boost pressure.

It's an interesting problem and one that must be well suited to electronic control. The problem is that diesel must be injected to initiate the flame, if there is too much propane present the diesel won't burn out cleanly because the propane being intimately mixed with the air will use it up faster than the diffuse diesel flame can grab it, if the proportion of lpg in the intake is near stoich then the diesel burning will cause detonation of the lpg:air mix at the pressures typical of a diesel. So it might be that the op's limit of

40% is enough extra energy to give more power without causing pinking or black smoke.

AJH

LOL!! :O)

In message , TVS writes

Nothing similar to the Corgi system although the LPGA would have us all think there is. Use of LPG for automotive propulsion is covered by Construction & Use Regulations, although to be fair (Oops that's a first) to the LPGA their COP 11 Code of practice is pretty much the same thing and more readable. All equipment must also conform to EU standards, the number for which I never could be bothered to remember.

Many insurance companies insist on LPGA certification of the installation.

There is no pressure regulator on the tank. The pressure is whatever is required to keep the propane in liquid form at the ambient temperature. As someone has already mentioned LPG can be very dangerous. It is heavier than air and when released can form a rolling invisible carpet along the ground. Don't be fooled into thinking it's gone when the white vapour disappears. That's condensed water vapour. It has been known for a flash back to be originated over 100 metres from the leaking tank. It will also for example happily accumulate unseen in a garage pit. Do not "just sleeve it" with high pressure hose. Use correct fittings. I don't mind you blowing yourself up, I'm just thinking about your family or neighbours.

Yes but you will almost certainly get far too much gas out using standard car equipment.

In message , Austin Shackles writes

My fingers aer dyslexic.

In message , TVS writes

Forget about achieving better economy with this type of system. We used boost pressure to switch the gas on/off but you could also use throttle position. A temperature switch is also advisable as it is not recommended to put in LPG into a cold engine. You will also need an LPG flow meter to make fine adjustments. They're not the easiest of things to get hold of but they are around.

I played around with a 200TDi with gas early last year on a rally log-booked disco! To be honest, it was rubbish. The gas was throttled by an extra throttle valve (Block of ally machined to produce a slide plate throttle, with seals of course) so that the gas only came in progressively from about 3/4 engine throttle upwards. There's a spare one available if you are interested, it bolts on where the aircon pump would go and you just need to assemble a linkage to the existing throttle links at the injector pump. I really can't say that I noticed a big difference in power with the gas switched on. It was running almost 2 bar boost pressure, with the diesel fuelling backed off to allow excess oxygen for the lpg burn, but no matter what adjustments were made to the gas side it really didn't pull that much better. I had my suspicions about the general engine condition though, because I've driven quicker standard 200tdi disco's, even allowing for the extra weight of the roll cage, gas tank, underbody protection, tripmeters, fire extinguisher systems etc etc. The mixer was at the turbo inlet, not something I was overly enthusiastic about when you consider the volume of pipework etc being filled with a weak gas mixture. Badger.

In message , Badger writes

If you back off the diesel and only allow enough in to ignite the gas then basically all you've done is change your 2.5 turbo diesel to a 2.5 turbo gas.

If you want more power you've got to burn both.

Yes

There is always the need to burn both, because the ci engine will not reach a high enough compression temperature to spontaneously ignite the gas, and if it did it would all detonate at once, the reason that this does not happen with diesel is that the diesel is injected over a finite period, combustion can only, initially, happen around the droplets. The reason it does not detonate in a spark ignition engine is that the pressure is lower and the flame front travels smoothly through the premixed gas and air.

The art of this fumigation must be in judging just how much of diesel and gas is best.

The only reason, that I can see, the gas will increase the power over diesel alone is that you could run at stoichiometric ratio, which diesels generally don't. I wonder if there is also the possibility of higher revs because the gas:air reaction will complete far quicker than the injector pulse and subsequent burn out?

AJH

Well aware of that Hugh, the diesel was backed off by approximately 10-15% at a rough guess, enough to notice the difference pulling up a local hill, but adding gas didn't even seem to restore the lost power, even up to the point of increasing the gas until it was smoking heavily on the reduced diesel. Just didn't seem to work out all that well whatever we tried, hence my thoughts about the basic engine being rather tired. Not that it really mattered anyway, wandering off-topic slightly, the owner was shit-scared to use the power it had on a forest rally stage, let alone any extra! He blamed the handling, we blamed his bottle! He fitted a video camera to the roll cage and video'd most of last year's "snowman rally", but got upset whilst playing it back in the service area when I announced "ok, so when are you going to select high range, my 110 goes through forests quicker"! Oops. Badger.

Lots of bottle-less drivers out there! I thought I was doing ok out in some fairly rough stuff recently until a mate's wife came flying past in their Pajero - in her case I think she's just too inexperienced to know what's safe (but maybe the problem's with my bottle).

On or around Tue, 08 Feb 2005 13:00:04 +1300, EMB enlightened us thusly:

Mind, I tend to the view that slower is better on rough stuff, unless you have to go faster to get through it. I always try things slowly first time; if it don't go, you can always try a bit more speed.

She'd make a good rally driver then - no brain, no pain! Unfortunately I wouldn't make a good rally driver - I know my limits!!

yep, lot to be said for that approach Austin, just that it doesn't wash when its a competitive event against the clock. Badger.

On or around Tue, 8 Feb 2005 09:09:01 +0000 (UTC), "Badger" enlightened us thusly:

well, that goes without saying. Unless, of course, it's one of those where accuracy counts, and speed gets you hitting penalty gates...