Isuzu G-series Twin Cam

A little sneak preview of what I'd ultimately like to set up on a G series engine. If I ever do it, I'll most likely set up on a single cam engine.

This is the future of LPG engines. Gone are the days power loss, excessive gas consumption, of gas rings or even mixers similar to a carburettor in appearance.

Enter the state of the art LPG fuel injection system.



Replace the petrol fuel injectors with these LPG solenoids.



The normal LPG converter is replaced with this injection specific LPG converter that can be adjuxted and fine tuned to provide different 'fuel rail' pressure settings.



I can see no reason why the Delco 808 couldn't be used as a means to control the whole system. The possibility of a performance LPG engine is real. Imagine an injected turbo LPG engine with full computer tuning control!

The Prins-Keihin LPG injection system.

I read somewhere on OzGemini that someone is meaning to convert his G161Z (or maybe G180/G200.. I think it was G161) to LPG turbo. Forget who, though.

There are a few done already. No one has injected LPG in a Gemini yet to my knowledge.

sweet give it to me give it to me
poida when do you think these will come out among local distribution?
i still havnt got my 4zd1-t lpg gem going yet but i do have all the gas research equip for it but its insane to try and find somebody to get it tuned etc etc

I'm just looking at it for now. I don't know if the LPG injection gear I showed is currently available through any Australian distributor. You might have to buy it direct from the supplier. It's not going to be cheap. Probably over AU$1000 just for the converter and the four solenoids by the time you get them landed here. There may also be import duty payable on it all.

I have two complete GasResearch packages and a complete tune up kit with all the different adjustment jets for the idle and progression circuits as well as a range of metering rods from numbers 49 to 55. Most dyno places should be able to tune but you'll need to see if they have previous experience with the GasResearch system. If they don't, copy the downloadable info from the GasResearch site onto a CD (or print it out) and give it to them to look over a few days in advance. Turbo applications are even more in depth of course and I'd probably be looking for someone with previous turbo charged GasResearch experience, full stop.

The sequence you use to set correct jets and rods is critical and if you attempt to do it in the wrong order you'll just keep going in circles. When running a turbo engine, you should probably buy a few extra metering rods to custom machine. They can be modified easily in any lathe.

While we're on the topic of alterantive fuels, I saw an American Gemini (Isuzu Imark) diesel which had been converted to run on chip fat/vegetable oil. This is nothing new, by all means, but it's the first Gemini I've known of being powered by it. I know someone who drives a Toyota Lite Ace (van) running a similar system. Fuel is literally free for him, he just asks fish and chip shops every few weeks, they happily give it away.

Biodiesel blended diesel is available commercially these days. Some independant companies heve been selling it. Look for the "greenfuel' truck depositing fuel into their tanks.

Poida wrote:Biodiesel blended diesel is available commercially these days. Some independant companies heve been selling it. Look for the "greenfuel' truck depositing fuel into their tanks.

The Diesel engine is called a Diesel engine for a reason.

Youve got to do some serious refining to cooking fats and oil thats full of burnt stuff to get them clean enough not to harm the engine or its componants.
They also add other stuff into the blends and it can fall out and the fuel turns to shit.

Ive seen a few vehicles that were running on "envirofuel" that was being sold out in laverton. My mate had them in his workshop drianing the crap out, changing the filters and putting diesel back in. It was 20-30c cheaper at the pump, the joint is shut now, says something about the quality.

Sorry bit off topic.

I say LPG is all well and good but once the government put their taxes on it it wont be cheap anymore.

Bob.

Last year on tha ABC show "The New Inventors" there was an aussie company in Sydney who sell LPG injectors. If you have a commodore for example you take out your onjectors and fit these lpg ones on place of them and plumb them into the gas. The ecu is untouched as the injectors were calculated for the flow needed. I cant remember the web site but if you search for this show it might have the links still on it. I think it was about $2000 for the whole system and the engine looked original.
gem.

P.S here is the link to the article : http://www.abc.net.au/newinventors/txt/s1345083.htm

Here is the wesite.
www.gas-injection.com

Some car manufacturers are actually selling off the factory floor cars with LPG injection now. The system I am pointing out is similar to that used in the lates model Ford cars. I'm in no rush to race out and buy just yet. I could be lucky to find a late Falcon being wrecked with LPG injection and a dead engine. One of the obstacles is the system is designed as a sequential injection system and I'll still be wanting to batch fire so the injectors must be calculated to deliver the right amount of fuel in two injection cycles per firing cycle. That means a smaller quantity of LPG, twice without the whole time factor becoming too short for smooth bottom end running, yet capable of delivering at full engine speed under maximum load. I passed in a sale on eBay where the seller had the converter and a batch of four injectors but they were the highest flow rate (73cc) types. That was just too high for my estimate.

Poida, you seem to have read my mind. Ive been thinking about this the last few days, i too am under the beleif that there is no reason why an aftermarket ECU could not control the injector/solenoids. Only limiting factor for me is the lack of current information, ill be leaving this sort of setup to the Piazza if it ever recieves engine work.

There are two types of Gas Injection out there at the moment - straight gas, and dual fuel. The straight gas type uses a completely new stand alone ecu, which to my knowledge utilizes some of the factory donor car maps with obvious modifications. The second type runs under the same principle, except that it uses the conventional petrol ECU to start the engine then switches over to gas. There is a kit out there for the Rodeo 3.5 V6, a mates driven one and has reported it drives identical to the petrol version.

Nick-

I didn't see this thread until just now, I have posted some info in another thread about LPG injection. If you want any details PM me and I wll PM or email back some info.

n.b.This is not a cheap exercise and believe me when I say that even in WA you will have to put in some more money to pay for the fitment.

Thanks STORM. I read that other post and you write my thoughts well!
While the subject has been revitalised, I'll add a few more of my thoughts.

Most people are wanting to run LPG in conjunctionm with the original petrol injection system. That isn't what I am setting out to do. Dual fuel is ok but in my eyes it's a compromise. You have to set up an engine to operate in two different modes but one thing you can't tune into that equation is compression ratios. LPG is ideal in an engine with 11.0:1-12.0:1 compression ratios. Pertol engines just don't need that high a ratio, in fact if you ran petrol in it you would only be using highest octane pump petrol. Regular ULP would be a thing of the past.


LPG injection currently comes in two forms. One is as per the Prins-Keihin style of systemn that I have shown at the start of this thread. It uses LPG that has been converted to a set pressure in vapour form. The solenoids used in their system act in much the same way as a set of injectiors do with petrol. The LPG vapor is regulated and supplied by a common rail. as each sloenoid valve is signalled by the ECU it opens for a timed sequence and LPG vapour is fed into the manifold port. This system is designe to be used as a dual fuel system with the petrol injectors still in situ.

The other system I have been watching uses liquid LPG right to the port where it is delivered by a specialised 'injector' nozzle.

Both systems use a specialist EMS that piggy backs to the cars OEM ECU. Now I think that is primarily for ease of fitment to a wider variety of vehicles as well as most people will still wish to use dual fuel.

I want no part of petrol if I go the LPG injection way. Straight gas means no need for any of the petrol components. I am wanting to adapt a Delco 808 ECU so it does with the gas what the OEM ECU normally would with petrol and do away with the expensive piggy back system. I can't see why the programming of a delco can't be altered so it delivers the correct quantity of gas instead of petrol.

Hi Poida.

I agree with nearly everything you say in your previous post except for the compression ratio. Unfortunately LPG has very little quality control and sometimes the Octane rating of LPG is not uniform. Up until a few weeks ago I also believed that LPG had a high Octane rating and could therefor handle decent compression ratios. What stopped my belief in this was when I did my LPG course at TAFE a month ago. We had LPG from different places and put it in the cars we worked on and run them on a dyno. With one particular blend of LPG all cars that did not have a knock sensor pinged and the car with the knock sensor was down on power. If the blend is pure (or mostly) Propane it is good and can take high compression with an octane rating of about 110. If however it has a fair bit of Butane the Octane rating will be similar to our current standard unleaded because Butanes octane rating is around 80. Those of us who are lucky enough to live in major centres usually get good LPG while crappy LPG goes to rural/country Oz. If you travel alot, like I do, then it is a good idea to keep the compressions at a moderate level and fit knock sensors if the car is computer controlled. As for having an 808 delco, or any delco for that matter, run an LPG injection system I can honestly see no reason why it couldn't. To my mind it could run either/or when the LPG switch is flicked without a piggyback ECU in the system as well and this is what I intend to do soon.

I have to agree there is a degree of uncertainty about the high compression engine I am building. It's experimental so there are chances I don't get it right straight out so I'll tread carefully until I'm sure it works. At this point I'm just starting to get my ideas into the real form.

I'm in no rush. Both engines have been machined over six months ago and are just being stored till I am ready to finish them. Last thing I need is to be over excited and cause damage by being impatient. I don't care if they don't fire for another year to be honest. The sound of a high comp LPG firing up is something to hear. They have a real sweet tune from the extra compression and sound a lot like a race engine. Very responsive off idle and crisp. The last two I was involved in building were small block V8 engines. One a 351C Ford engine and the other a 302 Chevy small block. Both HAMMERED and sounded really nice.

I'm building two engines and both will have knock sensors as part of the package. One is a 1.5mm O/S G161Z engine fitted with standard replacement hypereutectic pistons. That one is using a head which was only released on the very first TX models that were 8.7:1 where all following models were 8.3:1. It uses a noticably smaller combustion chamber and this one has been machined so I estimate it to be around 9.2:1 CR.

The other engine is a standard bore early TX block G161Z that cleaned up with a hone at 4.5mm O/S. It is fitted with the high comp forged pistons. The head on it is a G200Z head which has larger combustion chambers so it will reduce the compression ratio. The block has been decked just to ensure a true and flat face and the head has also. Minimal metal removed!

I'm hoping the forged piston engine works without knock but I agree there may be some chance of knocking, especially if a batch of fuel is high in butane. One of the features of the Delco gear I am going to use is a switch device that allows multiple tune packages to be set on a single eeprom chip. If I play it safe and set up a 'safe mode' tune for times when the fuel turns out to be a bit average I can still expect reasonable running without putting the engine in s situation where it risks damage.

Australian standards do specify that it cannot be greater than 50% butane in the mix. Rightfully that is still more than I'd like but that's one more reason why I'd like to use the liquid LPG injection so the gas actually cools the incoming charge of air as it mixes. If the worst scenario happens (problens with knock) then I'll be ordering a copper head gasket of suitable thickness to decomp enough to stop the problem.

Both engines are being built with graphite type head gaskets.

Poida wrote:I'm building two engines and both will have knock sensors as part of the package.

I didn't know knock sensors were available for the G series engines. Where did you find them and could you share info like part numbers etc for them?

I understand your liking high comp engines, I do to but my need is to have LPG as the main fuel but when I am traveling I need to be able to use unleaded just incase LPG is not easily available. I am not aware of to many LPG outlets in the old Oz Outback so I do need to keep the petrol capability and thus the low comp engine. To me an optimum is about 9.5 or even 10 to 1 for a modern ECU controlled engine, the chev gen 3 has something like 10.25 or something like that. On an older non ECU controled engine I would stick to 8.5 or 9.5 to 1 and have a Dissy recurve that wouldn't make the engine ping on petrol. My old 4 litre 3F Toyota engine could not take a load at all on petrol because the guy who set it up before I bought the car gave the engine way to much initial advance on timing. This is why I like the Delco idea so much, like you mentioned having 2 maps set up so you can have the ECU run the engine to suit the circumstances it is encounting. Modern ECUs have made the use of alternative fuels so much easier while still being able to use petrol.

I'm going to experiment with different knock sensors and different knock filters from existing Delco memcals. Once again it's a challenge to find a suitable one. I'm hoping to pick up a few parts through a contact in the US who can ship them over to me. Quite a few four cylinder cars used the Delco system and some were fitted with a knock sensor. I'll try and see what sort of signal I can filter out with a V8 Commodore setup but I expect it might return false readings.

As for long distance outback driving, that's why I also have diesel cars. They can run on anything from diesel to Avtur and anything in between. I've run my diesel Gemini on drums of aviation turbine fuel intended for helicopters and crop dusters before. It does no harm. Most outback properties have turbine fuel and some places sell it as diesel too. When you have to ship it out you ship something that can be used for multi purposes so the aviation fuel is the most critical because it's needed in aircraft. Can't run an aviation turbine on diesel so it's fuel gets the preference.

Poida wrote:I'm going to experiment with different knock sensors and different knock filters from existing Delco memcals. Once again it's a challenge to find a suitable one. I'm hoping to pick up a few parts through a contact in the US who can ship them over to me. Quite a few four cylinder cars used the Delco system and some were fitted with a knock sensor. I'll try and see what sort of signal I can filter out with a V8 Commodore setup but I expect it might return false readings.

The knock sensors themselves are pezo microphones. The different part is the knock filter on the memcal, which is an audio filter circuit that only lets the correct frequency for a knock of the engine its tuned for through. Ive read that if you cant get a filter for the engine you have, get one for an engine of the same capacity. Therefore, a v8 commodore sensor, with an imported filter from a memcal of a 4 banger with the same literage of your engine should work. So far I havnt been able to find what 2L engines had the 808 or 165 or variant delco with the filter. Anyone know?