Joined: 19 Oct 2007 Posts: 88 Location: The Netherlands
Posted: Wed Nov 07, 2007 2:18 pm Post subject: LPG versus LPi versus VSi......
Hi there,
Some of you asked me for some extra information on this subject.
I thought that it was simple, just the Gas versus injection, but as so many other simple things this ain't the fact!
I'll try to make myself clear and support this with some links.
LPG= Liquified Petroleum Gas aka Liquid Propane Gas is a mixture of Propane and Butane.
VSi= Vapourous Sequential injection
LPi= Liquified Petroleum injection
Under normal circumstances LPG enters the engine in a vapourous condition.
We all know what troubles this can give.
VSi goes one step futher, still vapourous but "injected" with help from valves who run on info/timing from the ECU from the car, multipoint injection is a must!
LPi is at this moment the most advanced form of LP powering.
The still liquified "gas" is injected with the stock injectionsystem
The engine is kept cooler because the liquid needs to go to vapour wich brings temperatures down alot!
LP... is so much cleaner as a fuel then diesel or petrol because it doesn't contain benzeen sulfer and lead!
It "burns" better in the engine and has a higher octanerating (MON/RON) then petrol between 90 and 110!
Do i need to say more........
excellent summary - ive been reading up on this myself since you mentioned it.....my question...i have installed an LPG tank for a vapourised injection system and also a filler etc but none of the engine side of the conversion yet.
Can I use my existing tank if i change my mind and go over to LPi?
Does it suffer from freezing issues in cold weather?
Would I still use the same gas filling stations or do i need a different formulation?
I know import subarus have a different map to compensate for higher octane ratings....is this something worth considering in a UK spec car do you think?
Joined: 19 Oct 2007 Posts: 88 Location: The Netherlands
Posted: Wed Nov 07, 2007 7:58 pm Post subject:
richbaker78 wrote:
excellent summary
Can I use my existing tank if i change my mind and go over to LPi?
Does it suffer from freezing issues in cold weather?
Would I still use the same gas filling stations or do i need a different formulation?
I know import subarus have a different map to compensate for higher octane ratings....is this something worth considering in a UK spec car do you think?
Hi there Richbaker78,
Thanks!
I do think that you can use your existing tank.
As i explained the "gas" is a mixture of Propane and Butane, when the weather changes the mixture is adapted.
Not by you, but by the distributor.
The hotter, more Butane.
The colder more Propane.
This has to do with evaporationfactor of the gas.
No, you don't have to change from suplier, it's all the same.
Your last question is an interesting one.
Compensation for higher octane fuel, does this mean to compensate using low octane fuel or protect from using high octane fuel??!!
I think that most ecu's adapt there programming when specs change like sensor input from knocksensors thus changing ignitiontiming.
Funny thing that i noticed though, information on Wikipedia varies from country to country.
Why don't you E-mail Vialle?
There international so i'm certain that they speak english.
info@vialle.nl
I hope that i answered your questions.
Regards,
Paul _________________ convertin' a VW T2 t1 '69 15 window "splitty" into a daily driver, to be continued.......
yes that answers the questions - thanks! i will contact vialle as you suggest.
regarding the octane issue....when you get a japanese import subaru over here your supposed to have it tweaked to take the lower octane fuel (appparently - i havent done this as I have a UK spec car) so I was assuming the reverse would be true...or I suppose we have just found a use for cheap import ECUs
Joined: 30 Jan 2006 Posts: 652 Location: North Staffordshire
Posted: Sun Nov 11, 2007 5:26 pm Post subject:
I did some LPi investigation the other day after reading that thread. Previously I'd not heard of it, but it makes a lot of sense. I assume you do away with the need for an evaporator (presumably replacing it with a liquid pressure regulator), and get the evaporative charge cooling effect (as in nitrous oxide) for free. It amkes you wonder why anyone bothered vapourising the gas in the first place - probably because the LPG injection systems were a development of the older 'gas carburettor' systems?
I am just starting to fit an OMVL Dream XXI P LPG system to my EJ25 turbo engine, and was hoping I was using a pretty state of the art system. It seems not now there is LPi too!
Regarding the octane rating, for many years I have wanted to build an engine to run just on LPG, to take advantage of the high octane (and low cost...). There seems to be little or no literature available on this though, which is annoying. However, it recently occurred to me that if I use a turbo engine and increase the boost rather than the compression ratio, it will be easy to wire in a solenoid bleed valve which opens when running on gas. If all goes to plan this will allow me to run on petrol or at higher boost on LPG. If it doesn't go to plan, then it will probably be a very expensive mistake!
I found out the following about LPi:
'LPG' is a generic term for Propane / Butane, and or a mixture of the two. The specification available varies by country. In the UK LPG is pure propane (I think - the one not so suitable for low temperature use), whereas the rest of Europe gets a mix of various percentages.
LPi is being developed by both Vialle and an American company (independantly, I think). Seeing Vialle associated with it immediately got me interested, as I know they are the supplier of the factory fitted LP? conversion available very recentlu on non turbo Subaru's in the UK. A quick check on the Subaru UK web site resulted in confusion - it referred to the system as both LPG and LPi on the same page. It also mentioned that it is instaled at the Millbrook proving ground in the UK. They also did (probably 'do') the OEM intalls for Vauxhall too, also with kit from Vialle, I think. I reckon it probably is LPi on the Subaru OEM installation????
From looking on Vialle's web site, and Googling them, they appear to be a research company and OEM supplier, not an aftermarket supplier. I found nobody offering Vialle installation servives in the UK, or selling their products anywhere (this site lists them, but mentions no installation servives http://www.centralgaragecarcroft.co.uk/vialle.htm). This seems a pity, but someone has to do the research, and it probably takes OEM budgets to do it, rather than selling into the rather saturated market of cloned aftermarket systems, half of which are either rebranded products from someone else, or use 90% of someone elses components anyway!
This link is interesting as it describes the Vialle system, and confirms exactly how it works. This may answer your questions Rich? Note that the comparisons with older systems ignore vapour injection, and only compare with venturi / mixer systems ('gas carburettor'), which is a pity. My OMVL vapour injection system has a lot of the advantages it mentions because of this omission in the comparision:
http://www.suzukituning.com/General/VialleLPi/Vialle%20LPi%20Technical%20Manual.htm#_Toc26108855
Of particular interst is the section on the injectors. The 'bottom feed' inkectore look exactly like the bottom feed petrol injectors that are used on my EJ25 turbo. Could it be thet they are actually standard petrol injectors? - I can't see why not, but no doubt you'd need ones of a different capacity.
If anyone elso knows more about LPi or how best to take advantage of the high octane rating of LPG, I'd be very interested to find out more myself.... _________________ Regards,
Richard,
R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com
Joined: 19 Oct 2007 Posts: 88 Location: The Netherlands
Posted: Mon Nov 12, 2007 8:23 pm Post subject:
Hi there Richard,
Why don't you take a look at Megasquirt?!
If i was to experiment with this, i'd take the road that lead me to a standard higher compressionratio to make full use of the high octane ratio in the first place.
If you can get that going without problems, then a turbo wouldn't be a problem.
Only thing that should be monitored is premature ignition or "knocking".
I don't know if a standard Subaru ecu has this capability but i'm sure that the Megasquirt is capable of handeling a knockingsensor.
Then i think you can make optimum use of the cooling effect that occurs when the liquid gas expands and cools the mixture.
Regards,
Paul
BTW do you refurbish Porsche 914 5 speed transmissions? _________________ convertin' a VW T2 t1 '69 15 window "splitty" into a daily driver, to be continued.......
Joined: 30 Jan 2006 Posts: 652 Location: North Staffordshire
Posted: Mon Nov 12, 2007 9:42 pm Post subject:
Hello Smartdriver,
Thanks for the reply. I already have the turbo engine for the project now - an EJ25 turbo engine from a 2005 model Forester XT. I'll be fitting a knock meter and an air / fuel ratio meter (hopefully a wide band one) before I start running it on gas. I tuned a Beetle turbo engine years ago before you could get knock meters, and detonation cost me a melted piston and an engine reduild. Hopefully I won't make similar mistakes this time....
I started looking into Megasquirting a Subaru engine a couple of years ago. I still want to try it, but it's dropped down my priority list since.
My biggest concern about the standard Subaru engine management is the ignition timing. It optimises the advance by learning where the knock limit as you drive, and is known to take a week or so's driving to find the optimum timing. I imagine switching between petrol and gas will result in it never getting to the optimum settings, but at least it'll be on the safe side of detonation. If I can get it to run successfully on gas only, then the ignition should reach it's optimum timing. _________________ Regards,
Richard,
R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com
Joined: 19 Oct 2007 Posts: 88 Location: The Netherlands
Posted: Fri Nov 23, 2007 1:52 pm Post subject:
Hi there,
Just had a interesting conversation with sales from Vialle Netherlands.
Fact is that there is no G3 LPi gear for a Subaru, there busy designing one but there are some problems involving the 4 wheel drive from Subaru.
Why there are problems, don't know.
I tould the person with what i was busy doing.
He tould me that there was a company in Spijkenisse that build LPi systems for Subaru from Vialle, only thing was that i couldn't get the G3 label necassary to get the tax discount for your car.
In my case the magic word was "oldtimer"!
Cars older then 25 years don't pay the roadtax that acompanies your choice of fuel.
So in my/our case(s) there is no need for a G3 label then this company can get your Sub powered VW drivin on LPi (that is Liquified Petroleum injection)!!!
Yes, finally some good news!
Pricing was not bad also, 2140,00 euro's incl vat and labour.
I guess it'll get more expensive, because i'm gettin' me a large tank!
Why is Vialle that important, fact is that nobody else does Liquified Petroleum injection!
Yes, VSi or Vapourous Sequential Injection is commen.
LPi has the benefit of cooling the fuelmixture with loads of possibilities on Turbo'd-engines.
Regards,
Paul _________________ convertin' a VW T2 t1 '69 15 window "splitty" into a daily driver, to be continued.......
Joined: 30 Jan 2006 Posts: 652 Location: North Staffordshire
Posted: Fri Nov 23, 2007 2:05 pm Post subject:
Hello Paul,
That's very interesting. Are you definitely going fr the LPi system then? - if so it'll be interesting to hear what you think when it's up and running.
The fact that they can't fit it to a Subaru because of the 4WD sounds very odd. I can't understand how that can make any difference, as in every Subaru engine I have seen the engine management has nothing to do with the 4WD system. Maybe it does in the latest CAN bus equipped models, and somehow this causes a problem? _________________ Regards,
Richard,
R J Engineered Solutions
Quality Subaru Powered VW Components
www.rjes.com
Hi, this is my first post on this forum. Maybe I can contribute something useful here. I am also looking for an LPI system and found information on two systems, Vialle and JTG Icom. The main differences seem to be
the Vialle system using an extra ecu to operate the injectors while the JTG Icom uses the signal from the petrol injectors without an extra ECU.
The injectors are made by Bosch /Siemens and look like petrol ones. They are 16 ohm saturated drive.
On standard LPG systems it is recomended to use a flashlube system. This is like an oil pump on a two stroke engine and puts a special lubrication in the intake to save the valves from pitting since gas burnes somehow leaner or drier than petrol. I don´t know if it is nessesary with an LPI system where you have the ěntercooler´effect from the liquid gas.
Check out: www.autogasnachruestung.de
Since it´s in german drop me a line if you need translation.
Joined: 19 Oct 2007 Posts: 88 Location: The Netherlands
Posted: Sat Dec 01, 2007 7:29 pm Post subject:
Hi there vanhellsingvw,
Welcome to this forum......
I don't know about a flashlube system in LPi.
I think that LPi has that advantage you mention, and therefore do not let the valvesseats be pitted due to the higher temp's on normal LPG combustion
I do know one thing for sure though, if you need a LPi system, Vialle is the way to go!
I found one distributor who can help me out if i get my busproject going.
Regards,
Paul _________________ convertin' a VW T2 t1 '69 15 window "splitty" into a daily driver, to be continued.......
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