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LPG injection systems for forced induction

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Fraud

Electrical
Jun 18, 2005
7
Hey everyone, long time lurker, first time poster (as far as i remember). I did a search and nothing came up so please forgive me if this has been covered before.

I've been looking around lately at LPG injection setups for a turbo project i'm about to embark upon, and I am incredibly interested in some of the injection setups that are around, however there don't seem to be many people singing its praises locally (Australia), let alone making the products commercially available.

Until this caught my eye a few months ago...
from what technical information is available about this system, can anyone tell me whether it would be suited to a turbo setup at all? the fact that it can be tuned from any ecu is VERY appealing. And yes, I am aware that it isnt currently available.

does anyone have any more information on this system? any ups or downs?

how would it compare to a liquid injection system (I'm not very familiar with liquid LPG injection)?

any information or feedback will be welcomed with open arms!

thanks

Nick
 
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I wont comment on a commercial product, but LPG injection is certainly a possibility. What type of engineering study are you embarking on?
All turbocharging accomplishes is increasing air mass by pressure, all things being relative to atmospheric pressure.
Australia is possibly one of the most advanced areas in the world with LPG injection (Italy, Netherlands the other two).
One reason there are almost no commercial products is that they have to be system specific for injector sizing, fuel composition, pressures, tank sizing and volumes, vapor or liquid, local or regional laws or codes, and so on.
Franz

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I'm currently finishing my grad. dip in telecommunications engineering, so this really isn't my area, this is more of a hobby, but from little things, big things grow. I have most of the concepts down.

And yes I had more or less worked out that the specific requirements for every application is what was preventing mass production of LPG injection setups. However it is frustrating that the opposite is not true for a traditional LPG setup - ie. I can take almost any car in for a traditional LPG conversion, and after some thought and planning, the required components can be ordered from a catalogue.

My preference for LPG stems from a few things, mainly greater knock resistance, and cheaper fuel prices (price parity agreement aside). I definitely like the idea of running a higher static compression ratio. There are a few other things, but the bit about automatically passing emissions tests if the car runs on LPG is a definite plus.
 
If an automobile automatically passes emission tests simply because it is running on LPG, someone is not paying attention. Although LPG is a very clean fuel, a poorly running LPG engine pollutes just as bad as a gasoline engine.
Franz

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I dread to think how many cars have been wrongfully passed simply because they run on LPG. My understanding of this ruling is minimal, but i'm led to believe its pretty loose.

Naturally, I do not intend to exploit this, but the emissions test is one less thing to worry about when it comes time to get the car inspected.
 
anyway, back to the general idea, has anyone had any experience with LPG injetion on forced induction engines? liquid or vapour, i'm all ears. What hurdles am I going to run into? Above and beyond all else, is there any reason it might be a bad idea to pursue this?
 
As an engineering forum for engineers, calculating the injection requirements with LPG as a fuel has little difference from gasoline, someone familiar with plotting fuel, air, and spark tables should be able to navigate.

As for the hobbiest, this is a complicated process, as LPG has different properties than gasoline, and even moreso with liquid injection, treat them as two totally different concepts.

Simply adding boost changes the reference PSIA with delta P., the base table reference when calculating the fuel delivery tables.

Also for the hobbiest, liquid injection is NOT a process I would like someone to pursue. Didnt you read a post on this forum dealing with liquid injection? Pressures encountered with liquid injection can reach 400 psig at the injector.

Franz

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Thanks BrianR, good to see manufacturers on the bandwagon..

the post from "notnats" above was also from me, that is my fathers handle and a combination of him not using the logout button and me not double checking before i posted means that things get confusing, so I'm sorry.

and FranzH could you please point me to that thread about liquid injection? I didn't see it while searching last week...

Thankyou all for your help!
 
Right below yours,
thread71-129931
There are also plenty of prior references too, do a search.

Franz

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In Europe there are lots of LPG gaseous systems able to work on forced induction engines...just search on google "lpg sequential injection"...almost all of these systems can be fitted into turbo or supercharged engines...on the LPG's forum I'm moderating more than 10 users currently own one on a turbo car, mostly Volvo with low pressure turbo, but Audi A3 with high pressure too. They all translate gasoline injector (on almost real time) signal to LPG injector signal, while emulating gasoline injection signal...this allows European OBD compatibility. Original gasoline ECU runs as master and LPG's ECU as slave. You can tune LPG's ECU with a dedicated software via RS-232 or USB notebook ports...makers offer specific car model upgrades, too.
 
Forced induction has problems of it's own with LPG. A lot depends on how and where the gas is introduced into the system.

The ubiquitous gas mixing valve placed at the blower intake would work, but then the entire induction system will be pressurised with an explosive air fuel mixture. People that have tried this have reported some fairly spectacular and destructive experiences.

Liquid LPG port injection is much safer for forced induction, but it is far from an easy thing to do. There has been some development work done here in Australia on this, but I have no details.
 
I'm talking about LPG multiport gaseous injection systems which are now actually the ubiquitous ones, since mixer systems cannot comply with EOBD and EURO4 emissions...
As for liquid injection there are a couple of commercially available systems now, the new from McClaren-Icom and the older from Vialle. These will be the way to go on future to keep LPG environmental advantages over gasoline....
 
Off course with these systems there aren’t backfire problems. However, in the long term I don’t know how valves(exhaust temps are already higher on turbocharged engines) would behave with LPG. I know, Franzh, that you don’t report any valve problems. But here in Europe (maybe because of smaller, low torque engines) we do. Citroen, as an example, recommends valve adjusting 3 times more often for its LPG cars than for the same gasoline model(none have “soft” valves).
 
I have experimented with the Icom system and am very impressed with it. My experience with engines that have valve problems extend to engines that do not have any ignition timing compensation for LPG's burn characteristics. When an engine is operated higher in its load cycle phase, it can possibly lead to exhaust valve burning. Here in the US, LPG engines on contemporary vehicles rarely operate much out of the lower 25% of its capability. Euro engines may well operate at a high load phase.
In the 70's, engines which were converted had multiple exhaust valve problems, but when hardned valves and seats were used, along with load compensated ignition timing, the problem has become almost non existent.
Franz

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The exhaust valves had concerned me, but to be honest, it would concern me more if i was converting a car that was petrol from the factory to LPG, because it would take the ECU a while to learn to advance the timing properly to make the most out of it.. especially in cars where the ecu resets itself to a standard setting everytime the battery is disconnected.

However, i'll be using a computer which has adjustable/variable load/rpm points to tune for both fuel and ignition, so i'm certain i'll be able to smooth it out correctly through the range... Of course, to be on the safe side, sodium filled exhaust valves are on the cards, but I'd probably use them on a petrol/gasoline engine anyway.
 
Using adaptive memory from a petrol ECM to learn LPG timing needs will not work. There are limits to adaptive learn, and when the parameters programmed in the PCM are reached, it may return to a default level, or go to a limited operation mode to prevent any engine damage.
Adaptive learn for timing advance is traditionally achieved by knock sensors which may never detect engine knock when operating on propane.
Just dumping LPG in an engine is not a wise engineering solution. There are many factors which must be dealt with.
Franz

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