Outer Limits 4x4 Board

Posted: **Thu Jun 04, 2009 2:47 pm**

I think I posted this one above, but it appears to be the most critical:

Abstract: The depletion of fossil fuels is understood by most energy users to be an inevitability. Researchers all over the world focus their attention on the development of various alternative fuels. It is believed that the use of compressed natural gas (CNG), as an alternative to conventional fuels will result in low levels of emissions. However, the use of CNG as the main fuel in a diesel engine with the diesel fuel used as an igniter has always been associated with some problems. The main problem in such a dual-fuel engine is the increased tendency toward detonation because of the high compression ratio of the engine. The current work is an experimental investigation of such a problem. An extensive experimental program was carried out on a variable compression ratio Recardo E6 engine. The results of the current investigation indicate that the dual-fuel engine can operate detonation-free for a compression ratio of 16.5. The results also indicate that dual-fuel engines are lower than diesel engines in brake thermal efficiency, brake power, and brake mean effective pressure at all loads. On the other hand, CO and NO emissionsare higher at high loads. However, at low loads, dual-fuel engines give lower NO.

Now this is a system with minimal diesel and CH4 as the main fuel, however...

EDIT, and a paper by CAT:

Design and development of a direct injected, glow plug ignition-assisted, natural gas engine
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Author(s): Willi ML, Richards BG
Source: JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME Volume: 117 Issue: 4 Pages: 799-803 Published: OCT 1995
Times Cited: 4 References: 5 Citation MapCitation Map
Abstract: Conventional (Otto cycle) natural gas engines are limited in power and thermal efficiency relative to a diesel engine due to detonation and the need to run a nearly stoichiometric air/fuel ratio. Technology is under development to burn natural gas in a direct-injected diesel cycle that is not prone to detonation or air/fuel ratio control limitations. Direct-injected gas (DIG) technology will allow natural gas engines to match the power and thermal efficiency of the equivalent diesel-fueled engine. Laboratory development now under way is targeted for field experimental evaluation of a DIG 3516 engine in a 1500 kW road switcher locomotive. This paper will describe DIG 3516 engine component design and single and multicylinder performance development.
Document Type: Proceedings Paper
Language: English
Reprint Address: Willi, ML (reprint author), CATERPILLAR INC, ENGINE RES, PEORIA, IL 61656 USA

Posted: **Thu Jun 04, 2009 2:50 pm**

Nice work.

But I see a spark-ignition one crept in there.

Any chance you can pull out any of these without having to pay for it? University contacts must be handy for that.

Posted: **Thu Jun 04, 2009 3:00 pm**

I just cut and pasted my search results. Have only had time to actually READ one or two so far. Which ones would you most like to read???

Posted: **Thu Jun 04, 2009 4:43 pm**

KiwiBacon wrote:
dumbdunce wrote: more than a few times. they are quite simple in principle. in the simplest case (eg a VE pump on a toyota 2L (or early 1HZ for that matter) or an inline port helix metering pump on a Nissan SD33, the ONLY inputs that control metering are RPM and pedal position - there is a force balance between the throttle input and the governor input that determines collar (VE) or rack (port helix) position. for a given rpm, a given pedal position will determine a preset injection volume.
I've only been inside inline governors, in those the maximum fuel volume continually varies with rpm as the governor rotates a control plate.
VE pumps must have a similar setup or they'd have to chose between blowing black smoke at high and low rpm or taking a big hit on available torque.

Take out all of the extra fluff (altitude, temperature, boost etc) and you still have a VE curve which is nowhere near flat. If the fuel curve can't follow that then you're giving away a lot of performance and creating a lot of emission problems.

dumbdunce wrote: definitely. I think we're saying the same thing, and that the point is that pedal position ALONE is not a reliable (or even slightly useful) input parameter for the metering of LPG into a diesel engine.
Yep.

dumbdunce wrote: For a system in such wide use there must surely be some published research with some numbers attached.
You'd think so wouldn't you? The DERB does mention a research paper I'll have a search for later.
But the typical uses of a fumigated diesels seem to be running on landfill type gases which are less susceptible to preignition/knock/detonation than the propane/lpg systems in great demand in aussie (due to a very low lpg price) which appear to have no easy to find supporting research.

The commercial systems appear to range from simple on/off gas flows to actively metered depending on boost, pedal position and egt. I haven't found a mention of air flow monitoring.
However, I haven't heard of any system having a knock sensor and this remains the primary concern.

supposedly D-GAS did research on big engines etc and got all the answers, but wont print there results because everyone will use all their wonderful information etc etc

and the new D-GAS system can incorporate a knock sensor

Posted: **Thu Jun 04, 2009 4:46 pm**

ISUZUROVER wrote: Hmm, looks like there are a few relevant papers:

mmmm exciting reading

Posted: **Thu Jun 04, 2009 4:56 pm**

love ke70 wrote:and the new D-GAS system can incorporate a knock sensor

Interesting.
I wonder how all the "knock deniers" feel about that.

Posted: **Wed Jun 10, 2009 12:17 pm**

ISUZUROVER wrote:I just cut and pasted my search results. Have only had time to actually READ one or two so far. Which ones would you most like to read???

I'd like to read the one you've quoted at the very top of this page. With the variable compression Ricardo E6 engine.

Posted: **Fri Jul 31, 2009 7:00 pm**

Just a follow up on the D-Gas saga, I was talking to an installer of another gas system last week and telling him about the dramas and lack of results from the D-Gas system, and he informed me yesterday that the company who supplies him is giving me one of thier gas systems free of charge including fitting and tuning.

They don't want to see the industry get a bad name so are doing this as a show of faith in thier product. Pity D-Gas can't or won't do anything.

I am having the system fitted when I get back onshore next week and will post up the name of the company after it's installed.

I have nothing but praise for the D-Gas boys in West Aussie who have tried to help me. As for the Sydney branch a big thumbs down.

To any of you thinking about putting a gas system on your vehicle my advise would be do as much research as you can and drive a vehicle like yours with gas on it before commiting to buy. And lastly don't believe a word that comes out of D-Gas's Sydney Salesmans mouth,all promises with no substance or backup....Cheers Gaz

Posted: **Fri Jul 31, 2009 9:05 pm**

Sweet - it will be very interesting to see what happens from here. I hope for your sake that you actually get something fitted that works!

Posted: **Fri Jul 31, 2009 9:51 pm**

I used to run a 1Hz T/D running between 8 and 16psi. It was intercooled and I changed the boost and fuel to try and get the best balance between power and economy.
The best power I got used 16lt/100km.
best economy I got was 12.5l/100km
That 4by was written off, now I have a 60 series.
This 4by has a 6.5lt V8 in it and is returning 11l/100km.
Shitloads more down low and although it is slightly slower in the higher speeds when I put the foot down, it is still a much better and driverable all up.

Bang for buck, I reckon the engine conversion is well worth it.....considering that is all you are doing. (i.e diff, g/b,transfer etc will add alot more to the cost of a changeover)

Posted: **Mon Aug 03, 2009 12:50 am**

Troopy93 wrote:Just a follow up on the D-Gas saga, I was talking to an installer of another gas system last week and telling him about the dramas and lack of results from the D-Gas system, and he informed me yesterday that the company who supplies him is giving me one of thier gas systems free of charge including fitting and tuning.

They don't want to see the industry get a bad name so are doing this as a show of faith in thier product. Pity D-Gas can't or won't do anything.

I am having the system fitted when I get back onshore next week and will post up the name of the company after it's installed.

I have nothing but praise for the D-Gas boys in West Aussie who have tried to help me. As for the Sydney branch a big thumbs down.

To any of you thinking about putting a gas system on your vehicle my advise would be do as much research as you can and drive a vehicle like yours with gas on it before commiting to buy. And lastly don't believe a word that comes out of D-Gas's Sydney Salesmans mouth,all promises with no substance or backup....Cheers Gaz

I still reckon it's a tuning problem, as I think it's a case of pumping in too much diesel/LPG and there's just not enough oxygen to burn up and produce the extra power that your after.

WHether this new system helps could be questionable and if it does then it could be due to having a proper tune up done on the diesel pump/LGP unit ECU.

A problem I've been having is the oil via the blow-by/EGR system I need a catch can bad (and I'll make one up) but currently I think it's really hindering the combustion bigtime due to the motor oil passing through the motor.

I don't have enough usable data yet but I'm getting around 16L/100klm which I know is pretty crap and can be a lot better as I used to get 800klm out of a 70ltr tank now it's around 500-600klm and I have a turbo on the motor.

Anyway shall wait and see what the end result is.

Posted: **Mon Aug 03, 2009 8:31 pm**

Personally I don't think it's a tuning problem, It has the latest D-Gas Version 2 TPI system on it now. This is the 5th delivery system" all D-Gas" that has been fitted and the greatest power benifit of 3.5kw at 38% gas was the original system.

It has spent as much time in workshops etc as I have had it over the last 13 months. It has had delivery pressures varied, dozens of different jets,2 injection nozzles, 1 injection nozzle, dynos etc and no one can get any performance benefit, and my fuel figures prove there is no economy benefit either.

D-Gas = Don't Give A Shit................

Posted: **Mon Aug 03, 2009 8:44 pm**

what AFR's is it running?
the only time gas is gonna give a benefit, no matter how shitty the tune, is when there is fuel and air left unburnt and it can scavenge that.
if you were making all the power the motor was going to with the amount of air it was being fed, then the diesel should have been dropped back and the gas substitute, to give a cost saving, but no power gain, as there wasnt the air to do it with.

if theyve given you 5 units, spent hundreds of hours working on it.
how are you saying they dont give a shit?
stop bad mouthing the company, theyve obviously done a shitload for you and your too naive to see its not their product letting you down

Posted: **Mon Aug 03, 2009 9:08 pm**

I'd say if a company offers a money-back guarantee but then refuses to give any money back, they could be said to "D-GAS"

I think it has been clearly stated from various viewpoints early on in the thread though, that LPG fumigation at any volume on a naturally aspirated diesel engine will result in a net power loss due to the displacement of available oxygen.

there are theories of the LPG acting to clean up and "complete" the combustion of available diesel fuel however this will only work (if it happens at all) in lean burn conditions and will not contribute to increased peak power - but may contribute to cruise efficiency.

if D-Gas makes a claim of power increase, it will be something like

"UP TO 20% more power**

** if your engine is 20% underfuelled before we get at it"

etc etc. it's like weight loss clinics - these results are not typical, your results may vary etc.

Did they deliver up-to X% power gain? yes. if you drove it nice (ie lean), it would probably have some $/km improvement too.

could you remove the kit, package it up, and ebay it, and put the $ towards a turbo kit?

Posted: **Mon Aug 03, 2009 9:44 pm**

love ke70 wrote:what AFR's is it running?
the only time gas is gonna give a benefit, no matter how shitty the tune, is when there is fuel and air left unburnt and it can scavenge that.
if you were making all the power the motor was going to with the amount of air it was being fed, then the diesel should have been dropped back and the gas substitute, to give a cost saving, but no power gain, as there wasnt the air to do it with.

if theyve given you 5 units, spent hundreds of hours working on it.
how are you saying they dont give a shit?
stop bad mouthing the company, theyve obviously done a shitload for you and your too naive to see its not their product letting you down

AFR's are in the 15-16 range from memory, been a while since i have looked.

I would like to change places with you mate and see your response if it was you in my position, the reason they have supplied 5 systems (they have not fitted them) is to try and get some benefit which has still not happened, they have wiped their hands of me and their guarantee is worthless. I'm shit canning them so other people don't get ripped off like me.

You don't sell this product do you??

A local mechanic who was in the process of becoming a D-Gas dealer has fixed the original butchered installation and fitted every other kit at no cost .

The original butchered installation was done by a certified D-Gas installer in Rowville who was recommended to me by the Sydney salesman/D-Gas spokesman.

I have even offered to fly the Sydney Salesman/D-Gas spokesman down from Sydney to fix it himself but he won't take up my offer, so is obviously not too confident in his product or his ability to get a decent result.

Need I go on?

Posted: **Tue Aug 04, 2009 12:05 am**

A mates got a 97 Troopy 4.2 NA on D gas and loves it, his was dynoed at about 10% more power, with better economy.
I also run D gas on my TD42t Patrol, I get more power and better fuel consumption, plus longer distances between fuel stops ,

whats wrong with yours!

Posted: **Tue Aug 04, 2009 5:19 am**

zagan wrote:
A problem I've been having is the oil via the blow-by/EGR system I need a catch can bad (and I'll make one up) but currently I think it's really hindering the combustion bigtime due to the motor oil passing through the motor.

I don't have enough usable data yet but I'm getting around 16L/100klm which I know is pretty crap and can be a lot better as I used to get 800klm out of a 70ltr tank now it's around 500-600klm and I have a turbo on the motor.

Anyway shall wait and see what the end result is.

I find this interesting. I have added a turbo to my 1HZ and while it pulls like a 13 year old who's just discovered masturbation it gets 16L/100 at very best. This is regardless of whether it is driven like a nanny or thrashed, fuel wound in or fuel backed right off to standard. I have found however that i am coating the inside of my intake manifold with oil from the EGR pipe. Andy from Dzltec suggested it might be because of the turbine housing because while it's a factory CT26, it's from a petty 7mgte and not a diesel. He suggested a dyno run to test exhaust manifold pressures but i havn't had a chance to do it yet.

I'll fit a catch can to see if that helps, I'll be doing it anyway just as a good practice thing. Before the turbo it got 12.5L/100 reliably every time.

But surely that amount of oil in the EGR (while annoying to see coating the intake and intercooler) wouldn't be enough to starve the engine especially after giving it 12PSI of extra air?

Posted: **Tue Aug 04, 2009 5:46 am**

zagan wrote: I still reckon it's a tuning problem, as I think it's a case of pumping in too much diesel/LPG and there's just not enough oxygen to burn up and produce the extra power that your after.

That's not "tuning", that is the physical limitation of a non-turbo engine.

You can only produce power if you have air to burn. With no more air to burn, you're not going to get a power increase.
Which is why anything which claims to increase the power of a NA engine that isn't a turbo is worth scoffing at.

Posted: **Tue Aug 04, 2009 5:52 am**

KiwiBacon wrote:
zagan wrote: I still reckon it's a tuning problem, as I think it's a case of pumping in too much diesel/LPG and there's just not enough oxygen to burn up and produce the extra power that your after.
That's not "tuning", that is the physical limitation of a non-turbo engine.

You can only produce power if you have air to burn. With no more air to burn, you're not going to get a power increase.
Which is why anything which claims to increase the power of a NA engine that isn't a turbo is worth scoffing at.

except hiclones.

Posted: **Tue Aug 04, 2009 9:00 am**

Maybe the vehicle is at its limits of power to make. If the diesel was backed off a little, then gas added it would/should make more power.

Care to post up some dyno graphs? What sort of power does it make at the wheels?

From what I've been told up to 10% extra power on a n/a engine is the norm.

Andy

Posted: **Tue Aug 04, 2009 9:14 am**

Dzltec wrote:Maybe the vehicle is at its limits of power to make. If the diesel was backed off a little, then gas added it would/should make more power.

Care to post up some dyno graphs? What sort of power does it make at the wheels?

From what I've been told up to 10% extra power on a n/a engine is the norm.

I'm offshore at the moment, so can't access the dyno sheets, they are not the printed graph ones, but from an analogue dyno .

The fuel has been backed off, wound up etc, backed off it's even more of a slug than usual wound up it belches black shit. The gas jet sizes are increased and decreased inline with whats going on with the pump.

Andy

Posted: **Tue Aug 04, 2009 4:51 pm**

Troopy93 wrote:
love ke70 wrote:what AFR's is it running?
the only time gas is gonna give a benefit, no matter how shitty the tune, is when there is fuel and air left unburnt and it can scavenge that.
if you were making all the power the motor was going to with the amount of air it was being fed, then the diesel should have been dropped back and the gas substitute, to give a cost saving, but no power gain, as there wasnt the air to do it with.

if theyve given you 5 units, spent hundreds of hours working on it.
how are you saying they dont give a shit?
stop bad mouthing the company, theyve obviously done a shitload for you and your too naive to see its not their product letting you down

AFR's are in the 15-16 range from memory, been a while since i have looked.

I would like to change places with you mate and see your response if it was you in my position, the reason they have supplied 5 systems (they have not fitted them) is to try and get some benefit which has still not happened, they have wiped their hands of me and their guarantee is worthless. I'm shit canning them so other people don't get ripped off like me.

You don't sell this product do you??

A local mechanic who was in the process of becoming a D-Gas dealer has fixed the original butchered installation and fitted every other kit at no cost .

The original butchered installation was done by a certified D-Gas installer in Rowville who was recommended to me by the Sydney salesman/D-Gas spokesman.

I have even offered to fly the Sydney Salesman/D-Gas spokesman down from Sydney to fix it himself but he won't take up my offer, so is obviously not too confident in his product or his ability to get a decent result.

Need I go on?

well i dunno mate, mine uses under 11 litres of diesel to the hundred, and a further 25-28% gas. which works out reasonably cheaper than it was on diesel alone, and im running a taller tyre now than i was on diesel alone, and it still uses less fuel. but i did it for the power up factor, not the money savings, but i know i would be spending more on diesel to make the power i am now

with the gas off i make about 59 kw, and with the gas on i make 75. and that was with a slow spooling turbo that wouldnt make more than 9 PSI, it now makes a controlled 13, and im yet to get it back on the rollers, but it makes alot more power, and uses no more diesel, so the savings have increased further.

and thats installed by myself, got the lines run professionally, and just banged it on a dyno.

with those AFRs, its pretty close to as much power as your gonna see from it by my understanding.

all im saying, is there is a reason your motor isnt making extra power, and its not because the D-GAS system is doing something wrong, its because the gas isnt helping.

people can hook a BBQ bottle up to their motor and feed it gas, and it gives a decent power gain, theres nothin special about the gas injection systems, so figure out where your issue is, because dgas has probably come to the same conclusion as me, its not their issue.

but i may be wrong, its happened before.

we shall see.

and no i dont sell it, nor do i bang on about it to everyone i meet, im just a happy customer, even if the systems are very basic, well definately the old one. and no business should cop a ballsing when they have so many units out there that work well, and one that doesnt because someones motor cant make more power..

Posted: **Tue Aug 04, 2009 5:11 pm**

love ke70 wrote:that was with a slow spooling turbo that wouldnt make more than 9 PSI

There's your point of difference. Right there in bold.

Posted: **Tue Aug 04, 2009 5:22 pm**

Here's a thought.

If all this work has been done trying to make the d-gas system work on your engine, and you are really *that* sure it is the system at fault, take it all off, put it into another car, and prove your point.

Otherwise we could sit here forever debating it and come to no conclusion.

Only logical conclusion I can see, as you have changed the gas system how many times now, and you seem to be willing to spend money to prove that their system is at fault.

If that also fails on an N/A engine, I personally would still not be convinced until you put that same unit on an already turbo charged engine.

Posted: **Tue Aug 04, 2009 5:47 pm**

i know mine is making the power because its turbo, because it actually has enough air to complete the burn, but the simple solution would be to turbo the motor in question and enjoy the benefits.

Posted: **Tue Aug 04, 2009 5:56 pm**

love ke70 wrote:i know mine is making the power because its turbo, because it actually has enough air to complete the burn, but the simple solution would be to turbo the motor in question and enjoy the benefits.

Yes, that is the what is on everybody's minds.... not sure why you would go d-gas b4 turbo anyways.....

Posted: **Tue Aug 04, 2009 7:13 pm**

marin wrote:Here's a thought.

If all this work has been done trying to make the d-gas system work on your engine, and you are really *that* sure it is the system at fault, take it all off, put it into another car, and prove your point.

Otherwise we could sit here forever debating it and come to no conclusion.

Only logical conclusion I can see, as you have changed the gas system how many times now, and you seem to be willing to spend money to prove that their system is at fault.

If that also fails on an N/A engine, I personally would still not be convinced until you put that same unit on an already turbo charged engine.

Thanks for your reply, but please let me point out the only costs to me so far have been the dyno's and running around. My greivance is that D-Gas guarantee results or your money back....they guarantee a minimum of 15% diesel savings or your money back, they spruke 16% power increase on a 1HZ with 430000km on it.

I have got none of the benefits guaranteed. I was told to take it up with the original installer... The installer does not make these guarantees D-Gas does, thats my issue with them not honouring what they promise in the sales emails.

As I said before , another company has offered to supply and fit their system to my vehicle at no cost to me, after hearing about my hassles with the D-Gas systems.

I don't know if it will give me any benefits or not but it's a very generous offer and i will honestly report on the outcome the same as i have with the D-Gas systems.

My vehicle has used 12.5-12.7l/100km since i have had it and with gas the most i have saved is 0.012l/100km nowhere near a 20-30% diesel saving.

Note: They also spruke in their sales blurb that no one has asked for thier money back, well i have and it doe's not happen.

I have the paperwork and all correspondence etc at home, all filled out for a VCAT claim, but i'm waiting until this other companys system is installed and evaluated. "If" i get a reasonable improvement in power and economy I will be lodging the claim against D-Gas.

Posted: **Mon Aug 10, 2009 11:30 am**

marin wrote:
love ke70 wrote:i know mine is making the power because its turbo, because it actually has enough air to complete the burn, but the simple solution would be to turbo the motor in question and enjoy the benefits.
Yes, that is the what is on everybody's minds.... not sure why you would go d-gas b4 turbo anyways.....

or why you would bother with gas at all. i think it was dumbdunce who said in another thread that turboing is best bet for a 1hz (over gas). imo gas just adds complexity and cost.

Also i remember reading a 4wd magazine article on a gas conversion on both 4.2 and 3.0 litre patrols. basically the 4.2 benefeted the most because the 3.0 is more efficient to begin with. somthing to think about if you have a common rail motor.

Posted: **Mon Aug 10, 2009 1:39 pm**

oldmate wrote:Also i remember reading a 4wd magazine article on a gas conversion on both 4.2 and 3.0 litre patrols. basically the 4.2 benefeted the most because the 3.0 is more efficient to begin with. somthing to think about if you have a common rail motor.

The efficiency gain isn't due to the common rail, it's direct injection on the 3.0 vs indirect on the 4.2.

Modern commonrail engines peak efficiency is similar to direct injection mechanical engines from 20 years ago.

Posted: **Mon Aug 10, 2009 6:19 pm**

oldmate wrote:[... turboing is best bet for a 1hz (over gas). imo gas just adds complexity and cost.

it depends on your goals. gas SHOULD be able to deliver a significant measurable reduction in fuel cost $/km. however unless the engine was poorly tuned before the addition of gas, that running cost decrease will be at the expense of peak power.

for bolt on power, nothing beats supercharging (of which turbocharging is a subset)

Outer Limits 4x4 Board

D-Gas giving no benefits, anyone else having issues??