gas

Ok here we go with a can of worms! I have a RR LSe fitted with a 4.6l chipped RPI engine. Now I want gas to help with the running costs. Now here is the kicker, do I go for injection or not? Not too bothered about boot tank as like most tight for cash (christmas etc) so somesay injection is the way to go others say not worth the cost! Thoughts please. John

Reply to
jds
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Depends on what engine management system you have. If your engine has the big single rectangular plenum chamber with the throttle body situated central over the near-side rocker cover like the 3.5/3.9, then go for a closed-loop vapour system. Something well proven such as AEB's Leonardo for instance. If, however, you have the later "Thor" setup with the "rams-horns" inlet manifold and the throttle body at the front nearside, then play safe and go gas injection. The issue with the later management system is that as standard it not only has over-run fuel cut (like most), but it also cuts the spark as well - causing problems for the gas system. Badger. B.H.Engineering, Rover V8 engine specialists.

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Reply to
Badger

On or around Sun, 19 Dec 2004 07:49:36 -0000, "jds" enlightened us thusly:

does the 4.6 still have the normal alloy V8 manifold? I suspect so, and if so, then a single point system with electronic control (using lambda sensor) should be OK. make sure the vapouriser and the mixer are big enough for the engine.

Advice and (fairly expensive) kits from http://www/chrisperfect.com andwhile the kits ain't cheap they are available for DIY fitment (not thatdifficult if you have moderate-to-good mechanical skills) and are alsopretty good quality, IME - some of the early ones were a bit patchy, butthey seem to be pretty well sorted now. Got a kit derived from what hesells on my 3.5 hotwire disco, and it works well.

Reply to
Austin Shackles

On or around Sun, 19 Dec 2004 10:09:44 +0000 (UTC), "Badger" enlightened us thusly:

WTF is that all about? there's no point in cutting the spark as well as the fuel...

'ere, that's a point. Hotwire systems, over-run cut off. Does it do this, how and when? I assume it just doesn't just fire the injectors, but how/when does it trigger? I doubt it's possible to cross-connect it with the gas system, but it'd be nice.

someone suggested that the flapper system has a vacuum switch which triggers the ORFCU - and that I could fit one of them, which is an idea. Since it's got an ecomax vacuum thing, it shouldn't be too uneconomical on over-run, but previous experience is that cutting the fuel makes for better engine braking, which would be handy sometimes.

Reply to
Austin Shackles

My thoughts exactly Austin, but it does! If it senses an overrun condition it cuts the fuel. If it then senses fuel cut for more than a certain time, it cuts the ignition until it gets a signal to end the fuel cut - then it reinstates both fuel and ignition, ignition first. It's the ignition cut that causes the gas backfire on reinstatement. You "can" wire the gas side into the coil trigger and in the case of the AEB Leo. it will simply cut the gas and default to petrol on the overrun as it senses the ignition cut, thinking the engine has stalled. On resumption of sparks, it will assume that the previously "stalled" engine has restarted and will change back to gas. Not ideal, but it works ok - as long as you can refrain from suddenly flooring it from an overrun condition. Biggest issue on thor engines anyway is the plug leads and coils breaking down, in my experience.

It does it magically by the ecu detecting high enough rpm's but no fuel demand (throttle pos'n tx) and cuts / reduces the pulse width supply to the injectors. I'd imagine you could use an electronic monitoring of the injector output pulses to control the gas solenoids, or in the case of the AEB Leo. it has overrun cut-off (variable) already within its programming and you tell it the rpm / default gas flow when setting up.

I seem to remember discussing that with you well over a year ago now, it's a vacuum operated switch which operates the relay next to the resistor pack / coil, lifting the rpm sense lead input from the ecu. Ecu thinks... "no rpm, best I stop injecting fuel"! As the vacuum level drops (manifold pressure rises) the trigger is reinstated and the ecu recommences fuelling. Always thought about rigging it up myself but never bothered due to the low mileage my 110 does these days. Badger. B.H.Engineering, Rover V8 engine specialists.

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Reply to
Badger

If this engine has come with a GEMS management system - like the 4.6 HSEs - don't use a singlepoint LPG system ; the GEMS will (over a period) try to correct any slight mixture errors, which won't work of course. The (petrol) mixture setting goes further and further out of spec while you are running on LPG. The end result is that when you do run on petrol it will be very poorly. It'll fix itself but it takes a looong time. The "lambda emulation" used by most singlepoint LPG systems to try and fool the petrol ECU that all is well just isn't accurate enough for GEMS. It's fine for earlier 14CUX systems.

LPG injection systems cost more, suit some engine setups better, aren't prone to backfire, and perform better once setup correctly.

Have you considered an upright toroid tank? Its a big doughnut that fits in place of spare wheel on a RR classic. Keep fullsize petrol tank, keep usual boot space, nothing extra hanging down below. You end up with a spare tyre to lose somewhere - it could remain on boot floor - at least its moveable. Or carry outside on a carrier. Tank costs more than standard cylinder though.

As with any conversion; do your sums to see what's worthwhile. Running costs approx 45% less, work out the saving over how long you expect to keep the car. If you do 20,000 miles a year you should have had a conversion ages ago! If you do 2,000 miles a year it isn't worth it unless you expect to keep the car for decades.

good luck Rossko

Reply to
Rossko

Thanks for all the replies, Just to clear things up abit.

!993 Range Rover LSE (long wheel base!) Standard Hot wire fuel injection, Same as 3.9. Ali plelum Chamber as 3.9 Cracked block in standard 4.2 so fitted An RPI 4.6 still with standard injection only chipped the ecu.

Reply to
jds

I wouldn't go multi point injection with this setup - any minor saving you make in fuel economy is minimal and the cost of a multi point system is a lot higher than a single point injection system. Just make sure you get a decent single point system that will run in closed loop. Personally I'd recommend the Tartarini Tec 97 or similar as, having had a number of different LPG systems fitted, each from a different manufacturer, it's the only one that has run entirely without a hitch and has never caused a backfire.

cheers

Dave W.

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Reply to
Dave White

I have no vested interest in this as I am no longer involved in the conversion business, I just know what I would do if I was converting my LR 90 V8(4.0 litre same as P38 RR) from scratch.

Reply to
hugh

5 gas vehicles of my own through time now, 4 on AEB Leonardo, 1 on star-gas. Never had a backfire on any of the AEB equipped cars, and had almost no problems at all (bar a P38 with ignition issues) on any others that I've converted - probably around 30 or so now. Personally I'd fit the AEB system, but then every installer will have their own favourite that they are used to. :-) Badger.
Reply to
Badger

If they were "a bit" cheaper to install I'd agree but given that the last time I looked "a bit cheaper" equated to the best part of a grand. I just don't think you can justify paying near double the amount for a conversion that gives you no real benefit.

Were it a Thor engine I'd have recommended the multi-point but the Thor is a completely different kettle of fish to the 4.6 in question. If you think a multi-point system will give enough of a benefit to justify the extra cost then I suggest you post that as a reply to the original post rather than simply criticising someone else who could be bothered to answer.

cheers

Dave W.

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Reply to
Dave White

On or around Sat, 25 Dec 2004 21:49:22 +0000 (UTC), Dave White enlightened us thusly:

valid point. Multi-point injection has advantages, but not as many as you might think and not as many as for petrol. The objection that single-point is "like a carb" is partly valid, but you can run single point closed loop, and get the improved mixture control that EFi on petrol gives. The other point about multi-point injection on petrol is that you're not dealing with vapour in a petrol system; you're dealing with atomized liquid petrol, like a cloud is lots of fine water droplets. Running LPG you *are* mixing vapour with the air, and it both mixes more easily and stays mixed. Petrol, especially in a cold engine, will tend to condense out of the mixture on cold surfaces, which is AIUI the main reason why petrol engines need enrichment to start when cold. The gas systems have no such enrichment and start fine from cold provided it's not so cold that the gas won't vapourise in the first place, but you don't get that kind of temperatures much south of the arctic circle, seeing as we're talking significantly below -30°C.

The really major point about multi-point injection is that you don't fill the inlet manifold with gas, and thus you (almost) can't get backfires.

There's a lot to be said for liquid-phase injection direct into the cylinders (like the new petrol GDi engines) - the vaporisation of the liquid fuel in the cylinder would lower temperatures in the combustion chamber and would increase efficiency; but the kit to do it is not easily available.

Reply to
Austin Shackles

Were do you get you figures from? Round here a multi point injection costs about £500 - 600 more than single point on a V8.

Bit touchy aren't we. I happen to have specific knowledge of tec97 on

4.6 hse but I won't give details publicly. (libel laws and all that) The OP can make up their own mind can't they? ( The original post has long since been deleted from my news stand.)
Reply to
hugh

In message , Austin Shackles writes

That's the danger with analogies - they get misinterpreted. I wasn't suggesting - oh never mind, I'll probably just make the hole deeper.

One of the characteristics of the conversion business is that it has moved on from the pioneer stage to the consumer stage and customers are less tolerant of what you and I ( and most owners of genuine LRs) would regard as challenging little technical problems. Consumers will be off to Trading Standards to complain. From people I've spoken to the multi-point systems are a lot less hassle once installed and set up correctly. As one installer told me, "They go out and we never see them again"

Is it available at all yet?

Reply to
hugh

About £800 difference for a rover V8 (rangie) from my regular supplier.

Hugh, how can you say he is touchy? I think he has a valid point insomuch as; A. it isn't a Thor and he's already said that if it were he'd recommend the multi-point; and B. You did criticise a response, not answer the OP; and C. do you honestly believe that the extra complexity of a multi point system would show an extra £800 worth (my figures) of benefit?

Oh, an if you wish us to believe that you have knowledge of a system, tell us! Don't say such rubbish as your last paragraph above. How can it be libellous to say "I converted a "somethingorother" using "kit x" and had the following problems/observations? Claptrap!

Badger.

Reply to
Badger

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