Need knowledge/opinions from the LPG gurus.

[V8Patrol]

A couple of questions:

Is gas injection legal and reliable? I was looking into it for my latest project and was told to hold off for a while...

Next is carby selection: Correct me if I am wrong but would you only use a gas ring if you had too on a duel fuel setup? Or is it dependant on the converter used? It would be easy to machine a ring into a throttle body for a neat and compact setup...

By far the best looking setup is the GRA carby, but everyone I know that is using one has spent ages fine tuning them (I have machined many metering rods!!). Even Gas Research Tech dept. have said that the impco has excellent fuel control and is easier to setup. I have been told that they are more sensitive to LPG quality as well although I don't understand how or why... Great for turbo and hotrods?

For reliability and ease of use that seems to leaves mounting the Impco. If you were for a gas only setup on a TB42S, would it be an advantage to remove the carby and replace it with a throttle body (from what car?) and attach the gas carby to that? Can you adapt the 300A to it neatly or would you use a 225 or a 425 which are easy to mount?

Also, assuming that you have electronic ignition - what timing curves are people using on a gas only 4.2?

The gas injection is legal and is undoubtly the go for performance and ecconomy but like all new inovations its expensive at the moment to fit, If you have the dollars to spend go for it!
Fatherinlaw is currently experimenting with a EFI falcon motor.... he hopes to run injected gas & injected fuel in it via the same fuelrail.

Here's the experiment so far.....

1: Leave the end of the fuelrail where the petrol comes in alone.
2: Cut the other end off ( blanked off from factory) and fit a gas lockout valve to this end of the fuelrail. ( requires a fitting and bronzing)
3: Fit a regulator that allows liquid LPG to run at 30 PSI which is the same pressure as the petrol in the fuelrail.... this is the hard part as LPG normally runs at 100 PSI pre the convertor.
4: Wire in the petrol and gas lockout valves.

It sounds simple enough and should work but there's a few roads to cross yet...... but if it works it would be an inexpensive conversion for motors that are allready fuel injected....... time will tell!

[V8Patrol]

I'll try and get a pic of a gas injection setup on a LWB patrol, problem will be the owner....he's a shift worker and rarely home.... but I'll try over the w/end if anyones interested to see it.

this post just made me a "rock stacker"..... wots that ???
Kingy

[jessie928]

Excellent innovation, the main problem may be the standard fuel injectors getting flogged out because of the LPG, and the spray pattern or no spray pattern at all, LPG has completely different properties than petrol, the gas turning vapour blah blah blah....., injectors freezing....
that said, it would be intesting to say the least.
Jes

[V8Patrol]

Like I said it's experimental at this stage, the freezing problem along with the hot/cold motor properties, alltitude usage problem etc etc etc, will all have to be considered and overcome. A simple solution is to cut a slot in the injector to allow a "fan spray" instead if a "stream spray", this greatly reduces the freezing problem, another fix it would be to remove the injectors from the cooler running intake manifold and place them directly into the combustion chamber. Another fix may require special injectors that can inject vapourised LPG. The list goes on .........
There's going to be lots of problems associated with anything thats "different" from the normal.......just think of what we would be driving if someone had never wondered .....
" What would happen if I put a diff in the front aswell as the back of this car ??"

[Wendle]

Thanks guys, too much info for me, my eyes are doing these ones
Was at Hazard's place yesterday, had a look at his gas install on his VH45, and worked out what we are going to do with mine, after reading this thread and all the knowledge within.

Get rid of all the emmisions rubbish and stare and marvel at a clean, neat engine bay.

Throw in some form of electronic/igniter/optical ignition and shorten the curve.

Run the Drunken-Warthog convertor that I already have and see how it goes.

No carby, all your talk of carbies has confused me and makes baby jesus cry! We will just run an impco butterfly doodad on a 50mm throttle body bolted up to the nissan manifold, and plumb some 3" flex with an inline filter of some sort to suck air.

Does this sound decent?
Thanks again..

[V8Patrol]

tooooooo easy ..... have ya finished it yet ????????

[Wendle]

:D tooooooo easy ..... have ya finished it yet ????????

all going well, I am going to do it when my missus goes down to phillip island for the bikes next month, that way I can use her car to burn around and get all the stuff that I forget to buy up front!

[turps]

just on gas injection I thought there was huge problems the cylinder going from very cold when the gas is injected then, hot after it ignites then cold again. Which led to the need to run alot of ceramic bits in the engine to stop it self destructing. But I have heard that engines with this set up go really, really well, for a short time though.

Turps

[mickrangie]

just spoke to some LPG guy...

he said that in Aust the quality of our LPG is crap and the direct injection isn't reliable so they stopped producing conversions for it

whats the go??

what other ways are there of having a proformance gas systems??

[V8Patrol]

As soon as Mick comes off night shift I'll get some pics of his setup. He also has all the paperwork from spec sheets to dyno tests before and after and he said he'd get in touch with the manufacturer for me.....time gentlemen ................. just give me some .

[hazard]

Elgas LPG is the highest octane and most consistant quality.

LPG is a has less energy than petrol but higher octane so if you are looking for a performance setup - add turbo(s) and don't decompress the motor. When injection gets sorted - yipee, but for now just use an impco or GRA carby and wind up the ignition to the limit with individual coils fired by a Haltec IG5 with knock sensors... The knock sensors will help if you tank up with a lower quality LPG blend, and the impco seems to be less sesitive to quality too.