Isuzu G-series Twin Cam

I've been playing with a thought for a long time now... We all know fuel is ridiculously expensive and is only going to get worse, and that the only smart thing to do is either give up driving pointlessly around (and we all love doing that) or look into alternative, cheaper, cleaner burning fuels.

I was just wondering if anyone could shed a bit more light on the topics of Gas Injection and Ethanol. I've heard that for gas injection you still need some form of funny gas carby - I'm probably very wrong here, but what is the situation here? Is converting to gas mainly a case of fuel pumps/lines, compression ratio, and ECU settings?


And as for Ethanol - I know perfectly well that, like gas, ethanol can provide much more power and efficiency than regular octane fuels. The main thing which needs to be altered is ECU settings, and sometimes compression ratios (in turbo setups suffering from pinging). My only concern with running an ethanol mix, or even straight ethanol is whether it will destroy my twincam. The main threat is rubber - are there many rubber components which would be exposed in the G-series DOHC engine? And does ethanol eat into any forms of metal? Would it cause any other problems? I was thinking that there might be a coating which could be applied to ward off any ill effects. Would running straight ethanol be a good idea/legal for street use? And I know availability might (at this point) be a bit of an issue.

I'm not looking for a too in-depth answer here, as I'd feel too guilty taking such a big chunk out of everyone's personal time! But any bits and pieces of info, links, thoughts etc would be appreciated.

Dont feel guilty - the more knowledge the better really.

The problem with Ethanol is it is a dry burning fuel. When the fuel/air mixture is drawn into the cylinders, some of the fuel slightly wets the bores and lubricates the rings. Its not enough to pass the scraper ring, but enough to keep the upper two lubricated [unless ofcourse its running as rich as a pig]. Ethanol is dryer, and thus wear is increased. To get the engine to run on it without any real dramas would require some thought in the choice of rings, some bore liners made from different material and maybe some mods to the valve stem seals or seats.

Unfortunately, although cheaper to produce, the higher powers that be dont really market it cheaper. They figure if your going to pay $1.35 for ULP, they can ask that of you too and you'd probably pay it too. Less costs to produce = higher profit margin.


Ive had a think about Gas Injection too, and its principles work similar to that of EFI. You'd need the usual gas shit like the tank, gas lines etc - pretty sure you DONT need a convertor like a GRA item as im pretty sure on the injected setups the fuel is injected in liquid form. The parts that are unknown to me are - fuel pump and ECU. I doubt you could use a regular fuel pump as everything inside it self would likely shit itself, and the ecu is abit of an unknown - will an aftermarket ECU like a Microtech be capable of running the Gas injectors, or does a different unit need to be used? Do you still need things like oxygen sensors etc?

One thing i do know is the injectors are ridiculously expensive - try 700odd per injector! Until more development is done by gas companies and manufacturers like Ford, Holden etc, it is unlikely that this would be a viable option unless you want to trial-and-error and lunch a few motors in the name of development.

Nick-

I know my MegaSquirt II could handle a gas injection setup. Well 99% sure. It can handle variable resistance injectors from 4ohm (low) to 16ohm (high).

... I'm gonna pretend that injector price was a typo is that high flow stuff?

I wonder if there could be a lubricating or tougher coating which could be applied to the bores, or to sleeves in the bores, to aid lubrication running ethanol. Don't mind me - I've been getting into the idea of coatings lately... I might email a few coating sites. Probably wouldn't be too cheap if it was a less common coating though.

Yeah the injectors ARE that expensive. Blame the stupid spray pattern being different because of the properties of the liquid being flowed. As for flow, fucked if i know.

Shouldnt need to apply a coating to the bores to reduce wear - its simply a matter of researching a ring and bore-sleeve combo that will work/resist contact. Ie cast iron bore sleeve with chromoly rings etc.

Nick-

I'm seriously looking into the idea of injected LPG in a G161Z engine. I'll probably be looking at vapor injection to start with. I'm using a standard bore G161Z with forged pistons and soft cast iron rings. The theory is to wear and replace rings so I precerve the cylinder walls and the pistons. I expect to run three or four ring sets through it. It's a standard TX G161Z engine that cleaned up easily by honing it to 0.0045" oversize to suit the piston clearance and away we go. It's a bit of a spin to find a TX engine is so good a condition. The crank is standard as well and got by with a polish. It's around 12.0:1 CR and should run fine with injected LPG.

I'm guessing that the vapor injection doesn't need the really expensive injectors? Is that the type with the carby-type thing instead of a throttle body? Or am I way off... I'm still a gas noob. I would have offered you my G161z, but, well, yeah... Funny story there.

Would chrome rings wear away at the bores less, and last longer with standard bores? And how much/how hard is it to sleeve bores? I should probably be calling around at this point, but as Nick said, the more information, the better.

Does anyone know if ethanol can be purchased cheap in bulk? I think you can buy it from my work (Foodland!!) for between $1.50 and $3/L so it'd be much less in bulk, but I have no idea on how pure that'd be, etc. I might call up ChemSupplies, if I can find their number.

I think some are getting mixed up with the differences between LPG injection and LPG carburetion.

LPG injection is relatively new in OZ but it has been through a lenghty evolutionary process in Europe. LPG carburetion is old as the us of LPG in cars and that s pretty old.

LPG carburetion for most cars is fairly basic for most cars and most people simply need to use either an IMPCO or OHG setup and these setups will serve for years as they were designed in America for use on their cars which hardly ever get serviced, so they must be simple so that they don't need servicing. If you are going to go LPG caruretion do yourselves a huge favour and use IMPCO or OHG convertors and mixers (carby). Another setup which I like as it isadjustable for seting up and then you can leave it like an IMPCO or OHG is GasResearch. They have a throttle body setup like the throttle body on a V6 or V8 Holden engine. I have one on my troopcarriers Holden V8 and I like it for what it is.

LPG injection is the new thing in Oz and there have been a few companies and individuals who have tried to get a good setup. One was Liquidphase who had a couple of Falcons running around with it as Liquid Injection but it had issues that 10 years? later they are still trying to figure out. The best idea ATM is a Vapour Injection setup. GasResearch apparently developed a setup some years ago but from my knowledge they never released it to the public. There was a guy on the New Inventors who is tryig to get financial backing and he developed a system that totally replaces the EFI system,meaning ythe LPG injectors sit in the EFI injectors holes etc.

The remaining setups that are currently available are from SprintGas and the dealer for IMPCO and some others, just do a search on the net and you will find them. THe beauty of these systems is they use the imputs from the cars ECU/PCM to tell the LPG ECU what the sensors are reading. The LPG ECU then injects the 'correct' amount of LPG as a vapour into the engine based on the EFI ECUs mapping.

LPG injection doesn't use an LPG specific carby or throttle bodylike IMPCO/OHG/GasResearch, it uses the OEM throttle body that come on the engine originally. You simply drill holes in the inlet runners tep the holes with a gas thread, fit the gas ports and hook them up with LPG type hose to the injector assemblies. The LPG injection wiring usually connects to the cars original EFI wiring and runs in series with it to obtain the sensors signals.

These setups are in hot demand are worth from what I have been told at least $2500 at trade prices and from what I have been told their is a 4 month waiting list but to me they are worth it because if you run an ECU (not saying you should but only if you choose to) with 2 maps you can set 1 to EFI and the other to EGI to obtaing the best efficiency out of both fuels. This is what I intend to do with my V8 and my fathers V6. Those of you who wish to try this on a Gemi 4 PM me and I will email you some more info.