LPG technical

[jeffro ra28]

Hi,

Due to the rising price of fuel I have been researching the topic of LPG sytems of late.

So far i have found a few helpful links that have cleared up alot of misconceptions i had.

Australian LPG
http://www.lpgaustralia.com.au/displ...ubarticlenbr=9

LPG properties tech (READ THIS!)
http://www.propanecarbs.com/propane.html

Ignition advance tech.
http://www.acl.com.au/web/acl00056.n...e?OpenDocument

LPG injection
http://www.lpgli.com/features.html

LPG Vehicle government grant Scheme.
http://www.ausindustry.gov.au/conten...7A2EFBDB3D4AF7

I am looking at idea's for use of LPG with forced induction applications. I beleive there would be advantages because of LPG's higher RON and MON and its price!

I have almost ruled out problems such as high exhaust temps due to LPG supposedly burning hotter and poor lubrication qaulities of LPG causing valve seat recession.

There are two main options for the delivery of LPG in your engine
1: vacuum induction vapourizer system (old school)
2: sequential gas injection system

The superior system for a forced induction engine would be sequential injection system mainly due to the fact that it will not be as greatly affected by manifold boost pressure.

To overcome the problem of valve seat recession due to LPG's poor lubricating properties you can install an oil injection bottle. This is something that would have to be modified for use with forced induction engine with manifold boost pressure. As the standard bottle feed oil injection system solely relies on vacum to draw upon the lubrication oil. Anyone have any idea's to resolve this?

I hope this gives a bit of an insight to some people of using LPG.

Feel free to add any information/ comments/ abuse/ chatter

Cheers
Jeffro

[oldcorollas]

a big problem of LPG is the ratio of Butane to Propane.
Propane is good. Butane is not so good.
fuel companies want to maximise the amoutn of butane in LPG because it is cheap.. almost waste product
the reason they can't is the vapour pressure between propane and butane, at normal temps renders butane a poor choice of fuel
this means that they change the amoutn of butane to what they can get away with depending on summer or winter. summer = more butane as higher temps mean minimum vapour pressue is higher

with a normal vapour mixer and either draw thru or blow thru system, this is not so bad.

but with vapour injection, you have issues with the tank pressure on cold days, depending on the exact composition of the gas.
the issue is that you may only have 30psi of tank pressure on a cold day.. on a suck thru setup, no issues. on a blow thru setup.. as long as you are running less than 30psi, and can still get flow from tank to mixer, it is ok.
BUT, with vapour injection, there has to be a pressure drop across the injectors to get the flow high enough. if you need say 15psi pressure drop, and you only have 30psi in your tank... then if you run 15psi boost, then you have ZERO fuel flow.....
not good.

running pure propane is better as it has higher vapour pressure than butane mixes, but still, on cold day, you may have problems.
this is different to the converter icing issues, and to get around it, you may need to have a tank warmer, to get the tank pressure up to a better level...

[jeffro ra28]

Good points you bring up there stu

In reply to some of what you have said tho.

"Variations in LPG composition—These do not worry Liquid Injection as LPG vapour pressure and temperature are read to give fuel composition. The injector pulse is altered to give the required energy input. Vapour systems cannot do this and suffer the consequences of variation."

Can you see any big problems with a suck through vapourizer system for boosted engines?

[oldcorollas]

how many liquid phase injection systems you seen around?

blow thru vapour system is better, as there is less fuel in the inlet tract in case of backfire...

impco is better than gas research if you can use it. gas research = aplha-N TBI

anyway, people like MrShin have a lot more knowledge on gas...

[jeffro ra28]

I havent seen one liquid injection system. I thought they were relatively "newish".

Blow through is better then suck through? How would you overcome boost pressure holding back charge on blow though setup?

[oldcorollas]

eh? at least with Impco stuff, the convertor or mixer or whatever is boost referenced.. like a normal fuel rail on EFI car.

[jeffro ra28]

just what i wanted to know

[jeffro ra28]

So, i wonder what the boundaries for boost levels are with the impco setup.

[Darola]

Hey there... not sure if this helps... but the new Hiace van we use is factory gas injection... has a seperate gas rail and bulit in injectors then from each injector runs a short pipe....

the van runs great on it all day even with all the full load we run 24/7

i will get pics when im next working of the toyota setup

Ed

[amichie]

So, i wonder what the boundaries for boost levels are with the impco setup.

Impco claim 5psi

[oldcorollas]

Hey there... not sure if this helps... but the new Hiace van we use is factory gas injection... has a seperate gas rail and bulit in injectors then from each injector runs a short pipe....

the van runs great on it all day even with all the full load we run 24/7

i will get pics when im next working of the toyota setup

Ed

oooh cool! pics would be good no.. great and of convertor as well.

hmm, a friend of mine runs 14-16psi on XF falcon with Impco gear with no issues. main problem he found was there was not enough flow from one convertor, as at higher pressure the flow is reduced, so ended up with 2 convertors i think?
there is a guy with XF running 20-30psi boost, but i am not sure what setup it is.. might be the GRA TBI style?


edit, XE with Au engine on LPG, running low 10, high 9, 20psi or so
http://jp.youtube.com/watch?v=2o4xHo...eature=related

edit2: can7t find the one i'm looking fro but is famous in the falcon community in Vic

[jeffro ra28]

Dude that falcon does wheelies!!!!!! better send that link to COB


nioce. keep the comments coming.

[jimmmayyy]

I looked into this previously too. There are quite a few gas VL turbos getting around, though they all use the gas research gear. You'll need two converters though.. one is only good for about a max of 200 odd hp.

the gear that i was looking at was done by a group called profire in wa, but they we're still in testing stages then.

link http://www.profire.com.au/

[GasedT18]

Thanks Jeffro n' all,

there haven't been misconceptions amongst those who can do the sums and know a little about physics

Once it is recognised that LPG vapour/air 'old school' systems cannot achieve an ideal fuel air ratio it then becomes a matter of separating the charge.

BTW I've run an OMVL system, there is no separate mixer and converter - it's all in one unit. The only thing in the air induction system is a hollow ring that is close to the carby inlet diameter - it has three slots. The OMVL system is a feed-forward device where pressure drop sensing and delivery happen through the same output port. A port on the integrated converter/mixer allows an external pressure reference - e.g., pressurised manifold (turbo/supercharged applications). Cold mornings can be a problem. Electric charge heating is an option, I either started on petrol or used a bucket of hot water

Vapour sequential port injection - some gains are claimed. A slug of gas from an injector might be able to be crammed in ahead of air and you might get a better ratio, but not much.

Liquid sequential port injection, doesn't stay liquid very long Some charge cooling effect maybe, but insignificant in the scheme of things.

To get liquid phase LPG from tank to injector requires a lot of hardware. High pressure pumps out of and return into higher rated tank. Return is 'hot' and tank heats. High pressure rails - problem, trying to keep LPG liquid at under bonnet temperatures either a sludge of propane/butane ice or boiling can happen - hence return lines, precise pressure regulation needed. Very high pressure injectors needed - getting speed and pressure is costly. For inlet port injection hardly worth while.

LPG Direct Injection - liquid charge directly injected into cylinder. Allows ideal fuel air ratio (subject to cylinder atomisation issues). Charge cooling effect more pronounced.
Specialised injectors. Issues with getting and keeping LPG liquid as above.

Two liquid phase injection systems one Australian (Liquiphase http://www.lpgli.com/) the other Dutch based Vialle (http://www.vialle.nl ) were in litigation last time I looked and the Australian company was seeking venture capital.

Air Inject systems - pressurised air and fuel are separately injected into cylinder. Ralph Sarich's (http://en.wikipedia.org/wiki/Ralph_Sarich) company transmogrifying into Orbital (http://www.orbeng.com.au).

Cramming more in via turbo charging is probably the most cost effective option together with vapour port injection. However, preventing blowing the crap out of your inlet system is still a problem in the event of an accumulation of gas and a backfire probably a lot less so with injectors over manifold pressure/vacuum vapour systems. Blow through or suck through doesn't matter bomb proof is the issue!
I've thought of things like sprung manifolds, BOVs, etc but I'm too chicken to drive a vapour turbo car with an intercooler.

Straight propane is cool. There was a place in Melb where you could fill up with propane. The solution is for the LPG industry to force the Govt to in turn regulate the standards for LPG supply. If only we the citizens could get LPG at the cost the Chinese pay. Conversion of vehicles in Aust would be a blip on the supply side. The best thing our Government could do is to mandate that x% of vehicles be sold factory supplied LPG systems and to nationalise part of our reserves. Paying international prices whilst cutting down on emissions seems harsh - particularly in light of carbon tax - opening up channels vis-a-vis retro-fit and mandated % LPG, electric etc but to wait for market is too slow.

I'll know more about valve recession after I've pulled down my 3T. However, it think the valve recession problem is more a myth with engines that run modern solid hardened valve seats. Petrol washes oil off the cylinder wall as well as contaminating oil; lubrication is less compromised in gas engines over wet fuel engines. What exactly is in petrol that assists in lubrication these days? - no lead that's for sure, works well for engines not for brains.

If you want to blow in a bit of oil a dedicated injector could be used. Myself I'm more interested in water/methanol injection but know next to nothing about it. LPG can be prone to detonation and AFAIK water can be used to lower combustion temperatures.

Of course Toyota has done petrol direct injection. Not sure what models, any domestic?.

One good source of info is this web site, I've learned a lot - I've a URL in one of the discussion forums - but look elsewhere - franzh has a FAQ on LPG/Propane.
http://www.eng-tips.com/viewthread.c...=129976&page=4

There's also an LPG forum started by a Toymods member stradlater I believe? http://performancelpg.com

Whether it's the Stealth Injectors, Liquiphase or Vaille (apparently a company called Icom also do direct liquid stuff), or Orbital - all of this technology is unavailable to the current domestic market even (or especially) for enthusiasts. There's been the test cars and examples but AFAIK you just can't order component and roll your own. There is more going on in Europe with LPG DI I believe and it may be possible to source components. Orbitals tech is primarily being rolled out in the form of retro fitting two stroke engines. A lot of effort seems to be going into making sure that this tech remains out of reach to experimenters.

D

[oldcorollas]

i'm scratching my memory here, but i think one of the falcon guys in melb had to run two sets of the vapour injectors and 2 or 3 convertors to get the flow needed for decent power..
the injectors aint that cheap and 12 of the suckers just makes it not very cost effective, and you still have the vapour pressure issues..

Gased, is it "supagas" that is straight propane? (taxis use maybe?)