Diesel Gas

[Larns]

Dose anyone here with an Isuzu powered landy have the diesel gas hooked up? How much did it cost? And it it worth it?

:twobeers:

[Dougal]

Just for ****s and giggles I ran some lpg into the intake of my Isuzu while it was cold and idling.

I've heard many reports that the LPG quietens engines down at idle. Yes it did, but only because it raised the idle speed by 50rpm or so. A light touch on the throttle linkage makes it run exactly the same.

But the interesting part. If I ran just a little more lpg in then the engine started labouring heavily. It was detonating which was advancing the timing to the point where it ran rough.
This on a cold diesel running at idle with no boost.

I think you'd need a hole in your head (an extra hole most people don't have) to run diesel gas on any diesel.
More power, sure. But what's the cost?

[Rosscoe68]

not meanig to be rude, but i imagine the guys that produce the diesal gas systems would do more than just stick a gas hose into the inlet. my guess is there would be some tuning required. As in any modification whether it is diesel or petrol, n/a or turboed any mods like this without tuning afterwards could be disasterous. only thing is i don't know what amount of tuning there is available on the isuzu's, so i'll leave my comments a that.

with the recent bout of infighting i was loath to post, but decided to after all, like i said, not intending to be rude :)

[Dougal]

not meanig to be rude, but i imagine the guys that produce the diesal gas systems would do more than just stick a gas hose into the inlet. my guess is there would be some tuning required. As in any modification whether it is diesel or petrol, n/a or turboed any mods like this without tuning afterwards could be disasterous. only thing is i don't know what amount of tuning there is available on the isuzu's, so i'll leave my comments a that.

with the recent bout of infighting i was loath to post, but decided to after all, like i said, not intending to be rude :)

The fact is, LPG detonates in a diesel engine. This is caused by the high compression ratio of a diesel engine and cannot be altered by tuning of any description.
The only tuning that can stop that is to stop using LPG.

The BS meter is currently off the scale with some of the marketing claims being made about this. A little experimentation can show the problems clearly.
A little research will show the downsides outweigh the upsides, which is why no diesel engine maker condones the practise.

[Larns]

Yea guys...........constructive comments please.

I'm hearing what your saying about the detionation and such, but it's a little more complex than that, otherwise I'd rig it up myself.

I'm after actual accounts of people that have had it installed, I suppose it dosn't even have to be an Isuzu power pack, it would just be more relevent thats all.

Cheers

[Xavie]

Hey mate, I've decided to get it however it is for a tdi Engine. I recently saw someone with a tdi disco which had it on so I chased them down to ask how it was going etc... and this guy was very pleased with extra power. He said He probably gets a bit of fuel savings but he felt it was more about smoothness and drive-ability which were both improved. He had it for about 35,000 kms so far and said he'd probably stay with the tdi engine when this oen goes because with the gas it was ice to drive.

Xav

[andrew e]

There was a bloke at the pentith LR show last year running his isuzu on LPG (no turbo), and he loved it (he had OUTBACK LINK written across the front). He said it was smoother and had more power.

[abaddonxi]

Hey mate, I've decided to get it however it is for a tdi Engine. I recently saw someone with a tdi disco which had it on so I chased them down to ask how it was going etc... and this guy was very pleased with extra power. He said He probably gets a bit of fuel savings but he felt it was more about smoothness and drive-ability which were both improved. He had it for about 35,000 kms so far and said he'd probably stay with the tdi engine when this oen goes because with the gas it was ice to drive.

Xav

What were you driving when you chased him down?

Just for performance comparison.:p

Cheers
Simon

[4bd1discovery]

Dose anyone here with an Isuzu powered landy have the diesel gas hooked up? How much did it cost? And it it worth it?

:twobeers:

there is a $2000 government rebate for the gas system. all up it would cost about $1500 once you have got the rebate! it is worth every cent of it though especially with the new system dieselgas technologies has! and there is alot more required then shoving a hose down your tank! if you have any questions about the gas feel free to ask me!

[rovercare]

if you have any questions about the gas feel free to ask me!

You have LPG on a 4BD1?

You have LPG on a diesel?

What setup?

What sort of power increase and economy increase?

[4bd1discovery]

You have LPG on a 4BD1?

You have LPG on a diesel?

What setup?

What sort of power increase and economy increase?

the powr increase is phinomenal. my father has had hundreds of cars on dieselgas and is currently making a 4bd1t range rover with gas. the economy increase is reasonable, overall it makes your engine alot smoother and reduces egt's well worth every cent!

[rovercare]

the powr increase is phinomenal. my father has had hundreds of cars on dieselgas and is currently making a 4bd1t range rover with gas. the economy increase is reasonable, overall it makes your engine alot smoother and reduces egt's well worth every cent!

Hundreds? what?

So no 4BD1 then?

[4bd1discovery]

Hundreds? what?

So no 4BD1 then?

yeah my dad actually owns dieselgas technologies. they have fitted a 110 county they turbo and gassed it and it doubled the power! it had a 97% power increase. they also fitted a range rover 4bd1 with gas and it went like a skinned cat!

[rovercare]

yeah my dad actually owns dieselgas technologies.

Ahhhhh, I see said the blind man:D

[4bd1discovery]

Ahhhhh, I see said the blind man:D

yeah

[c.h.i.e.f]

1:gas injection is proven to be a very good product and has had extensive testing and development
2:if your dad owns diesel gas technologys what is his name?
3:where can i get this product installed these days?

[big guy]

Hi, I just had mine done here in SA.
I had at the same time a EGT gauge fitted.
It does not seem to lower temperatuers, quite the opposite actually, it raises it by 10-30 degrees.
What it does though is give me heaps more power/torque.
Ican go up the adelaide freeway without the gas on and flick the switch and off it goes. That simple. My max egt is 700 and that was flat chat up a very steep road in fourth and it was still pulling.
From all my research with people in the know like thermoguard.com the short term highest recommended temp is 720 degree C.

The gas does not flow at idle but does flow once the throttle is pressed.

A bloke on here did the install locally and its simple, quick and so far very reliable.:)

[p38arover]

You have LPG on a 4BD1?

You have LPG on a diesel?

What setup?

What sort of power increase and economy increase?

James should have put up a disclaimer. His father is one of the principals of Diesel Gas Technologies in Sydney.

[Landy Smurf]

just so you guys know the 2 brothers that invented this impressive system are members on here.if you type in gastek on youtube and watch the new inventors segment you will find out more about it. also they work in singleton

[p38arover]

Neither Derek nor Bruce are members on here (yes, 4bd1discovery and I know them both - as does MasterChief who is, I think, 4bd1discovery's uncle).

Bruce and Derek live in Dungog.

[lambrover]

this thread is turning into a urinating competition.

What it should be about is the mechanics of the system, how it works, why and benifits.

From what I have seen it is very benifical better fuel econimy and more torque, the owners of the systems I spoke too where touring Australia and towing and love the system.

I was under the impression with turbo diesels you inject befor the turbo and it mixes better and decreases the intake air temp.

[Landy Smurf]

i was talking to derek and he said he is and his brother is woko.yes they live in dungog but they work in singleton but apparently derek is looking to move to the singleton area.

[Dougal]

Since we have soo many advocates of the systems here. How about they provide some test data to show the gains in engine efficiency and fuel economy?

I'd also like to hear how they are avoiding detonation. Because diesel compression temps are above the autoignition point of the gaseous fuels they're using.

[lambrover]

Since we have soo many advocates of the systems here. How about they provide some test data to show the gains in engine efficiency and fuel economy?

I'd also like to hear how they are avoiding detonation. Because diesel compression temps are above the autoignition point of the gaseous fuels they're using.

I have a table here to look at.

because the auto ignition temp of gas is higher it relies on the diesel firstly being ignited the lpg assists in the burn.
big diesel engines have been using gas for a long time now, My old boss was working on a big Cummins genset with gas on it

[Dougal]

I have a table here to look at.

because the auto ignition temp of gas is higher it relies on the diesel firstly being ignited the lpg assists in the burn.
big diesel engines have been using gas for a long time now, My old boss was working on a big Cummins genset with gas on it

That doesn't really help. If the LPG can ignite on compression alone, then it can detonate before any diesel is injected.
The reason I ask is because my 4BD1T hates lpg being streamed into it. Audible detonation at very low concentrations even when it's cold and idling. A warm engine with boost makes things a whole lot worse. But those conditions also make it harder to hear.

Cummins has a range of westport engines which run on gas (lpg, cng etc). But they are designed for the purpose with compression ratios lowered significantly below diesels to avoid detonation and spark plugs for ignition (i.e. not a compression ignition engine).

I know an engineer who works for MAN with large diesels which can be run with gas. However they have steel pistons and may have other mods which no-one can tell me about (engines are built for each application).

[DeeJay]

That doesn't really help. If the LPG can ignite on compression alone, then it can detonate before any diesel is injected.
The reason I ask is because my 4BD1T hates lpg being streamed into it. Audible detonation at very low concentrations even when it's cold and idling. A warm engine with boost makes things a whole lot worse. But those conditions also make it harder to hear.

Cummins has a range of westport engines which run on gas (lpg, cng etc). But they are designed for the purpose with compression ratios lowered significantly below diesels to avoid detonation and spark plugs for ignition (i.e. not a compression ignition engine).

I know an engineer who works for MAN with large diesels which can be run with gas. However they have steel pistons and may have other mods which no-one can tell me about (engines are built for each application).

Don't forget LNG.:p
I work for an LPG distributor & even I can't say much. Because a lot of this gas substition is in its "infancy" ( its still being honed to perfection) most commercial operations - ie Murray Goulburn,Toll, Fox etc insist on confidentiality clauses. We can't get hard data feedback, unless we field trial trucks ourselves, and that ain't happening. Certainly earlier on (2 + years ago) there were instances of truck engines going Kaput, but investigation showed the cowboy element was at work & I'm not convinced the industry is rid of them. Lets face it, there were engine failures due to LPG at the same develpoment stage. Sure, the better HDV (Heavy Duty Vehicle) conversions are with highly modified engines, but most are heading toward 95% gas with 5% diesel for ignition and I believe compressions remain the same. Spark plug ignition is too expensive & a service nightmare, for HDV.
The bottom line is that it did work with N/A engines in a HDV environment.
Its just that by spending more on better technology, the payback is greater.
One thing for sure is, properly done, it will save millions off the fuel bills of these freight companies, there are 7X semi public LNG refuelling sites in W.A.(Kleenheat) & 5 going in to Tas right now (BOC)& these are trial sites. Not to mention all the Metro buses running around on CNG
I'm personally quite interested in converting my Isuzu Landie, but one of the guys at work used to be pretty high up at Isuzu Aus, and his statement to me about my Isuzu was "I wouldn't do it because of the potential to overfuel"
So I'm fence sitting :cool:
BTW, LPG does have better properties than LNG & CNG for engines, but of course its a lot dearer.

[bee utey]

That doesn't really help. If the LPG can ignite on compression alone, then it can detonate before any diesel is injected.
The reason I ask is because my 4BD1T hates lpg being streamed into it. Audible detonation at very low concentrations even when it's cold and idling. A warm engine with boost makes things a whole lot worse. But those conditions also make it harder to hear.

Cummins has a range of westport engines which run on gas (lpg, cng etc). But they are designed for the purpose with compression ratios lowered significantly below diesels to avoid detonation and spark plugs for ignition (i.e. not a compression ignition engine).

I know an engineer who works for MAN with large diesels which can be run with gas. However they have steel pistons and may have other mods which no-one can tell me about (engines are built for each application).

Having experimented with diesel gas enhancement, there are a number of things I have learnt or observed.

Firstly, LPG will not burn on its own in a normal diesel engine. At no stage will it ignite unless diesel has been injected and ignited first. This is true up to a massive amount of LPG which would cause major problems due to over fuelling. I now fit a micro switch to stop LPG flow at zero accelerator mainly not to waste LPG, nothing to do with self ignition...

Secondarily, the correct amount of LPG for diesel enhancement is way leaner than the point at which a flame can occur in the cylinder with LPG alone.

Thirdly, there is a change of combustion noise with LPG added, which gets louder as more LPG is added. It mainly indicates faster combustion. In this way more of the diesel fuel is burnt, causing cleaner exhaust as reported by testing of emissions. As EGT indicates most closely what happens in a cylinder the maximum temperature for a specific engine should be monitored if there is any doubt of the engine handling the LPG. An engine that has been modified to put out increased power continuously would probably benefit from piston and compression ratio changes.

Lastly adding LPG to a cold engine to increase power is not a good idea, and can be prevented by electronic settings (complex systems) or driver education (simple systems). So long as turbo waste gate limits are not reached the best time to add LPG is under load with the turbo boosting. Then the extra fuel will add turbo pressure to increase excess air.

The pure LPG/CNG engines you mention are of course specifically engineered, using spark plugs to initiate combustion and so bear only a superficial resemblance to diesel engines.

There are many succesful LPG enhanced vehicles driving around, but each engine type should be tested for durability before selling a kit to a vehicle owner.

Over to you, forum members...

[Dougal]

Having experimented with diesel gas enhancement, there are a number of things I have learnt or observed.

Firstly, LPG will not burn on its own in a normal diesel engine. At no stage will it ignite unless diesel has been injected and ignited first. This is true up to a massive amount of LPG which would cause major problems due to over fuelling. I now fit a micro switch to stop LPG flow at zero accelerator mainly not to waste LPG, nothing to do with self ignition...

Secondarily, the correct amount of LPG for diesel enhancement is way leaner than the point at which a flame can occur in the cylinder with LPG alone.

Why do you say LPG will not burn on it's own? Do you think it can't detonate below the LEL?

Again the reason I'm quite curious on this is my own experiments show that LEL is completely irrelevant for compression ignition. The LEL is for igniting cold gas with a hot ignition source. Quite different to the situation inside an engine.
I've had all sorts of nasty banging noises happening at concentrations of 1/5th the LEL.



Thirdly, there is a change of combustion noise with LPG added, which gets louder as more LPG is added. It mainly indicates faster combustion. In this way more of the diesel fuel is burnt, causing cleaner exhaust as reported by testing of emissions. As EGT indicates most closely what happens in a cylinder the maximum temperature for a specific engine should be monitored if there is any doubt of the engine handling the LPG. An engine that has been modified to put out increased power continuously would probably benefit from piston and compression ratio changes.

So faster combustion, faster pressure rise, giving much higher stress on the engine for the same power (or torque) generated?
Where does the line lie between faster combustion and knock?

I don't believe the cleaner exhaust claims at all. Any well maintained diesel can be tuned to run clean on diesel alone.



Lastly adding LPG to a cold engine to increase power is not a good idea, and can be prevented by electronic settings (complex systems) or driver education (simple systems). So long as turbo waste gate limits are not reached the best time to add LPG is under load with the turbo boosting. Then the extra fuel will add turbo pressure to increase excess air.

What are the potential problems adding lpg to a cold engine?

But the really interesting one. Australia seems to be the only country in the world with an LPG price low enough to make $ by substituting LPG energy in place of diesel.
The rest of the world appear to pay significantly more $/kJ in gas, which makes LPG as a fuel quite costsly compared to diesel.

[PAT303]

Since we have soo many advocates of the systems here. How about they provide some test data to show the gains in engine efficiency and fuel economy?

I'd also like to hear how they are avoiding detonation. Because diesel compression temps are above the autoignition point of the gaseous fuels they're using.

Maybe you should know what you are talking about before you jump up on your high horse.I have D/gas fitted to my Tdi,I have for quite some time now and it does make a very large difference to the engine,for your information the gas is not injected until the coolant temp is over 45 degree's and not before the engine pulls 6 psi of boost and the system is alittle more technical than a hose shoved down the inlet.My engine has never detonated,never run hot or has given any trouble at all since the gas system was fitted and I do recommend based on my experience D/gas on a Tdi,my engine just ticked over 424,000k's which is near the most K's of any Tdi on this forum so your opinion that gas is bad for then doesn't hold much merit. Pat

[bee utey]

Why do you say LPG will not burn on it's own? Do you think it can't detonate below the LEL?

Road testing. While gear changing under full load no power is produced while accelerator is lifted. Revs drop instantly. That is not to say it can't happen, only I have not noticed it at any stage of testing.

Again the reason I'm quite curious on this is my own experiments show that LEL is completely irrelevant for compression ignition. The LEL is for igniting cold gas with a hot ignition source. Quite different to the situation inside an engine.
I've had all sorts of nasty banging noises happening at concentrations of 1/5th the LEL.[/quote]

Possible as I have not fitted up a 4BD1T. The Rodeo 2.8 turbo I did was quite noisy under gas until I reset down the LPG delivery, it then drove around Australia succesfully.



So faster combustion, faster pressure rise, giving much higher stress on the engine for the same power (or torque) generated?
Where does the line lie between faster combustion and knock?[/quote]

Yes its all a matter of degree, I don't believe there's a high risk of replacing up to 25% of your diesel with LPG. More could be dicey. I have had no reported troubles at this level, albeit with a small number of conversions so far (10)

I don't believe the cleaner exhaust claims at all. Any well maintained diesel can be tuned to run clean on diesel alone.[/quote]

Possibly. providing you have plenty of air and good injectors. Emissions testing for post 2003 diesel enhancement systems is mandatory though, even the simple Eco-Shot system has managed to pass that. Every system fitted to these vehicles must have passed the test and be type approved.


What are the potential problems adding lpg to a cold engine?[/quote]

Excessive smoke mainly, cold diesel engines don't burn as well. The '03-on 3.0 TDi Rodeo gets around this by hardly fuelling until the engine warms, my mate couldn't get up my drive until it was warmed up 5 mins. Very little smoke at any stage of operation.

But the really interesting one. Australia seems to be the only country in the world with an LPG price low enough to make $ by substituting LPG energy in place of diesel.
The rest of the world appear to pay significantly more $/kJ in gas, which makes LPG as a fuel quite costsly compared to diesel.[/quote]

The 10-15% cost saving is definitely a bonus in Oz. Interestingly no owner has reported total consumption of litres of fuel going up with normal driving, even if they accelerate more. The much lower calorific value of 1 litre of LPG compared to 1 litre of diesel shows there must be more efficient diesel use. Otherwise the total litres of both fuels would go up.

[clean32]

Dose anyone here with an Isuzu powered landy have the diesel gas hooked up? How much did it cost? And it it worth it?

:twobeers:

in answer to your question

no i don’t have Dgas on my Isuzu

But I have seen two that have and one of then has since been fitted with a turbo as well
The other one now has over 170 000 klm running dgas NA with no problems apart from a couple of speeding tickets.

There are many dgas systems fitted in the world and we don’t have a pile of stuffed motors to even think about making a claim that it’s not feasible.

Is it worth it, well that’s really up to you? if you want a bit of economy and are prepared to wait a couple of years for it to payback ( depending on your mileage) then ok. If you just want more power and if the cost is a bout 1500 bucks ( after subsidy) then ok. If your handy with the tools and have access to a work shop then I would look at the Turbo on a budget thread. If you want a drive in drive out then 5-6K for a turbo kit fitted or 1500 for dgas fitted. Lastly if you’re a real tight type, there’s a thread started around here on a do it your self dgas system.

How it works ( basically)

The Gas is injected under its own pressure into the inlet manifold or pre turbo. Unlike an LPG powered car the mixture is week. In that it is unable to burn on its own because its just way to lean. There for there is no risk of backfires like LPG powered cars.
Because the gas in injected in liquid form strait from the bottle ( same as if you turn you BBQ bottle up side down and crack it open) its bloody cold on expansion. This cools the surrounding air making it denser, this is a good thing and has a similar effect as an intercooler.
The next thing is when it burns, because it is such a lean mixture ( extremely lean) it will not ignite in the normal fashion like an LPG powered car. How ever the LPG molecules do go though a transformation. " I will stop there because it get a bit hard to explain but lest to say it is a very similar process or action to how diesel oil is enhanced or a lower grade oil is brought up to a higher speck. Basically heat it, add hydrogen ( LPG) but do it all under pressure"

The LPG provides a lot more hydrogen molecules for the combustion process to play around with, in short. So it best to think of it as a fuel additive rather than a fuel in its self

Dougal is an avid poster on this topic and he has carried out one experiment to which he has concluded to the entire world and all on here that its rubbish. He did post a video of his experiment so it’s around here some where. If I recall it consisted of him using his BBQ and shoving a rubber hose up his manifold, personally I think it may have been the wrong orifice.

[shining]

Hi All
I had DG fitted to my 300Tdi in 2007 (at about 280,000kms). Had the headgasket done at the same time as I had boiled it once previously and suspected a slight blow through.

Reason for fitting- was towing a camping trailer and needed more Kw and Nm and didn't want to spend $30k on a vehicle upgrade.

Only went light on the gas being but liked the extra power and acceleration and was certainly noticable on the drive home from Sydney.

Economy - Unladen running around was 7lt/100km diesel 2.2lt/100km lpg ( previously 9.5lt/100km diesel only)so was cheaper on a daily basis but at my distance travelled it would take about 5 years to pay back the install cost. However the reason for the upgrade was effective towing and cheaper than a vehicle upgrade.

Comparision - 6 weeks camping around the Gulf and Arnhemland with another family in a 80 Series GXL (Turbo Diesel) with a similar trailer. He could still leave me behind but I would go as far on 90lt diesel and 28lt LPG (small tank only on a D1) as he did on 145lt in his longrange tanks.

Would I do it again? - not now that I have a D3:D but it served its purpose at the time. The D1 has around 350,000km and going well with no obvious ill effects - other than panicking servo attendents thinking I am fleeing the scene when actually only moving to the lpg pump :angel:.

[Dougal]

Thanks for your considered responses, I've got some more questions for you.


Yes its all a matter of degree, I don't believe there's a high risk of replacing up to 25% of your diesel with LPG. More could be dicey. I have had no reported troubles at this level, albeit with a small number of conversions so far (10)

When you say up to 25%, I presume you're comparing litres to litres. Is that 25% substitution at max flow (setting max gas flow based on a know max diesel flow) or is that 25% average use over a tank (say 80L of diesel to 20L of LPG).
Because depending on how and what you measure, the differences can be huge even if the numbers are similar.


The 10-15% cost saving is definitely a bonus in Oz. Interestingly no owner has reported total consumption of litres of fuel going up with normal driving, even if they accelerate more. The much lower calorific value of 1 litre of LPG compared to 1 litre of diesel shows there must be more efficient diesel use. Otherwise the total litres of both fuels would go up.

How much are you currently paying for a litre of LPG in Aus? In NZ we pay more for a litre of LPG than a litre of diesel. Which on a weight/weight basis makes LPG over twice the price.
As a result it's not economic to even replace petrol with LPG (disregarding conversion costs), if you had a high compression spark engine built for LPG you might just beat petrol running costs.

Why hasn't the maker of one of these systems published a dyno run to prove any fuel savings? It'd be very easy to do and add significantly to their marketing material.

[p38arover]

How much are you currently paying for a litre of LPG in Aus? In NZ we pay more for a litre of LPG than a litre of diesel. Which on a weight/weight basis makes LPG over twice the price..

Does your diesel price include the road tax or are you comparing pump prices?

LPG in Sydney costs between 1/3 and 1/2 the price (depending on time of year) of ULP or diesel.



Why hasn't the maker of one of these systems published a dyno run to prove any fuel savings? It'd be very easy to do and add significantly to their marketing material.

The only dyno runs I've seen (and I've seen a lot) are for power. I guess it's a lot fiddlier to measure combined LPG and diesel consumption.

[clean32]

Does your diesel price include the road tax or are you comparing pump prices?

LPG in Sydney costs between 1/3 and 1/2 the price (depending on time of year) of ULP or diesel.

The only dyno runs I've seen (and I've seen a lot) are for power. I guess it's a lot fiddlier to measure combined LPG and diesel consumption.

You have a good point there. But best not to get
Hung up on New Zealand road user charges. at 13.30 per 1000klm is a small cost
http://www.nzta.govt.nz/resources/factsheets/38/road-user-charges-1-6-tonne-vehicles.html (http://www.nzta.govt.nz/resources/factsheets/38/road-user-charges-1-6-tonne-vehicles.html)

I have posted before. I have lived and worked in a number of countries as well as traveling quite a bit. Australia is the only country in the world that I have ever come across where diesel costs more than regular petrol; something is very fishy in Australia on this topic as the explanations I have read are complete bollocks.

anyway fuel costs in NZ, 95 $ 1.95 diesel $!.13 and LPG $1,21

That roughly translates to AUD as $ 1.50 $ 0.85 and $0.90

http://www.pricewatch.co.nz/default.aspx (http://www.pricewatch.co.nz/default.aspx)

but your point is that as far as economy is concerned it would probably not be worth fitting Dgas in NZ

[p38arover]

There are many place in Oz where it would be hard to justify LPG conversion on petrol cars owing to the cost of LPG outside the cities.

[bee utey]

Thanks for your considered responses, I've got some more questions for you.



When you say up to 25%, I presume you're comparing litres to litres. Is that 25% substitution at max flow (setting max gas flow based on a know max diesel flow) or is that 25% average use over a tank (say 80L of diesel to 20L of LPG).
Because depending on how and what you measure, the differences can be huge even if the numbers are similar.

Good point. I am talking about usage from fill to fill. Some of my customers report a difference of 20% difference in usage rate between heavy hills driving (less LPG) and constant flat driving (more LPG). I can adjust the sensitivity of the regulator to reduce this difference. The system I use is arflow dependent rather than boost dependent, so the percentage of LPG drops against higher diesel usage.

Electronic systems are set for optimum/safe levels as a matter of course. My local wholesaler was experimenting with his company's injection technology and stated power/max flow rate limiting was an important strategy to maintain warranty compliance.

How much are you currently paying for a litre of LPG in Aus? In NZ we pay more for a litre of LPG than a litre of diesel. Which on a weight/weight basis makes LPG over twice the price.
As a result it's not economic to even replace petrol with LPG (disregarding conversion costs), if you had a high compression spark engine built for LPG you might just beat petrol running costs.

Adelaide LPG is currently selling at 70 cpl and diesel around $1.30

Why hasn't the maker of one of these systems published a dyno run to prove any fuel savings? It'd be very easy to do and add significantly to their marketing material.[/QUOTE]

It is so much a matter of driving style that it is hard to quantify in real world driving. Using the extra power is addictive. Even my most conservative customer mentioned regret when he ran out of LPG on a trip. And cost savings are all about price difference which are very variable even within 100km of any city.

[Dougal]

Does your diesel price include the road tax or are you comparing pump prices?

NZ LPG prices are pump including road tax. Diesel is not taxed at the pump for road use, road tax is levied seperately per km at about 4c/km for your typical 4wd.
The road tax is based on weight and axle loadings. Petrol and LPG are the only fuels here which include road tax at the pump.

The interesting thing regarding LPG performance (i.e. as a power adder) is no-one on LPG has reached power levels unobtainable by using diesel only. I have a whole lot of data on LPG which unfortunately isn't with me right now (on holiday in Europe) but I recall some people adding LPG with flowrates which equated to 80kw worth of extra fuel.

[land864]

I have a D -Das system on my 86 Isuzu.
It was on the vehicle when I bought it.
The PO fitted it for towing improvement purposes.
All other technical jargon and pay pack periods etc , etc , etc aside \I have to say it does make a diferenec when turned off or on .
As the saying about art goes..
"I may not know much about art but I do know what I like"
similarly , I may not know much about the techo and $ stuff but I do know I like it:D
Mine was fitted by 4WD connections in Eltham , Vic and has all the electroniccy needed.
I like it so much I am going to take it off the Suzu and see if it fits the TD5.

And Ron , I think he did declare a potential bias when on the 23rd he said his dad owns D Gas tech. ( Unless that was a later edit:) )

[slug_burner]

Is this what you are after in the way of a dyno run?

[clean32]

Is this what you are after in the way of a dyno run?

looks like you may have a bit of a breathing problem there

[c.h.i.e.f]

i would like to agree with Pat here !

i would like to add dyno dynamics dyno's have not been produced to give faulse/useless readings hence why they have probably been used in development in such systems as diesel gas and have not used there own way to figure out the performance of there vehicle via using slopes and product horsepower ratings like "some" people like to do ;)
i see that some people figure out horse power by saying there new intercooler is said to be 25hp gain so add the 25hp to the stock hp of the truck then they go and buy something else that is said to be so much hp gain and so on and so forth until they have came up with a truck that has twice the hp rating of the standard :eek: but the problem with that is they did not take into account when the standard engine is tested to be say 50hp the makers done the testing in absolute perfect circumstances (water being forced through the engine,air being forced past the engine via an external source,test fuel not sump oil like australia gets and the engine usually has no auxillaries such as alternator etc etc) so once the engine is put into its environment where it operates the hp rating has droped considerably.

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines

2.why has it been played with for so long if it is crap??? wouldnt they have gave up on it by now!!!

3.as others have stated it is a bit more complex than pouring coupious amounts of LPG into the air intake

4.and as for this pre ignition that some people are worried about that is probably one of the reasons why the system has a computer system to allow the correct amount of gas in at the correct time.

5.as pat said he has run it on his for "quiet" a few kilometers without any problems and tdi's are a bit more refiened than most other diesel engines on the market and if it has handeled it without any problems i dont see why other diesel engines found in landys would be different.

[isuzurover]

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines


Actually, which countries is it used in??? To my knowledge it is quite rare outside Australia.

The R&D has all been done by quite small companies. No engine or vehicle manufacturers seem to have shown any interest at all, however they have put a lot of R&D into natural gas.

I agree though that there seem to be increasing numbers of people with these systems fitted, and there don't appear to be any major issues. However there seems to be a need for some serious, independant research on the long term effects of running such a system.

[Dougal]

i would like to agree with Pat here !

i would like to add dyno dynamics dyno's have not been produced to give faulse/useless readings hence why they have probably been used in development in such systems as diesel gas and have not used there own way to figure out the performance of there vehicle via using slopes and product horsepower ratings like "some" people like to do ;)
i see that some people figure out horse power by saying there new intercooler is said to be 25hp gain so add the 25hp to the stock hp of the truck then they go and buy something else that is said to be so much hp gain and so on and so forth until they have came up with a truck that has twice the hp rating of the standard :eek: but the problem with that is they did not take into account when the standard engine is tested to be say 50hp the makers done the testing in absolute perfect circumstances (water being forced through the engine,air being forced past the engine via an external source,test fuel not sump oil like australia gets and the engine usually has no auxillaries such as alternator etc etc) so once the engine is put into its environment where it operates the hp rating has droped considerably.

gas injection
1.its not going to be crap considering so many countrys around the world reconise it as being a benefitial upgrade for diesel engines

2.why has it been played with for so long if it is crap??? wouldnt they have gave up on it by now!!!

3.as others have stated it is a bit more complex than pouring coupious amounts of LPG into the air intake

4.and as for this pre ignition that some people are worried about that is probably one of the reasons why the system has a computer system to allow the correct amount of gas in at the correct time.

5.as pat said he has run it on his for "quiet" a few kilometers without any problems and tdi's are a bit more refiened than most other diesel engines on the market and if it has handeled it without any problems i dont see why other diesel engines found in landys would be different.

There are a multitude of ways to measure power, dismissing one method of measurement because it doesn't involve a big shiney machine with lots of user-set variables suggests a lack of understanding.
Dyno readouts are well known for variation as well as giving the customer the numbers they want, their best use is comparison on the day.

As Isuzurover has said, outside Australia very few people care about lpg fumigation. The only reasons it's done in Australia are cheap gas and government subsidies. If gas cost more than diesel (as it does in most places) and you had to pay the whole $4k yourself. Why would you do it?

In the US and Canada people have run it for power gains, but they seem to have give up. The problem appears to be a lot of broken parts for a small power gain. Diesel alone gives more power without the problems.
So yeah, they've given up on it.

In spite of all the marketing out there, it is about adding lpg to the intake. That's all these systems do, the only things they can change is how much they add and when.

What is the correct amount of gas? How much is safe and at what point does engine damage result?
Simple questions with no forthcoming answer.

[isuzurover]

Hmm - there seem to be a few studies being done - however mainly on engines combusting small quantities of diesel and large quantities of propane.


Shock tube investigation of propane–air mixtures with a pilot diesel fuel or cotton methyl ester

H.E. Saleha and Mohamed Y.E. Selimb, Corresponding Author Contact Information, 1, E-mail The Corresponding Author

aMech. Power Eng. Dept., Faculty of Eng., Helwan University, Cairo, Egypt

bMech. Eng. Dept., College of Eng., UAE University, Al-Ain 17555, United Arab Emirates
Received 27 June 2008;
revised 9 September 2009;
accepted 10 September 2009.
Available online 25 September 2009.

Abstract

The propane (or LPG) is one of the best candidates as an alternative fuel in dual-fuel engines which operate primarily on any type of gaseous fuel using pilot injection of diesel to achieve ignition. The ignition delay has received considerable attention in the published literature for various gaseous fuels using different dual-fuel engines which showed that the ignition delay in a dual-fuel engine is different from that in a diesel engine especially at low loads. In this research, the measurement of ignition delay of propane–air mixtures with a pilot diesel fuel or cotton methyl ester (CME) similar to mixtures used in dual-fuel engines have been performed in a shock tube. The operating conditions were the equivalence ratio ranging from 0.3 to 1.2, the initial pressure varied from 0.4 to 1.0 bar, the initial temperature varied from 423 to 673 K, the relative mass of pilot liquid fuel and the type of liquid fuel. The ignition-delay times were measured using a piezo-electric pressure transducer, charge amplifier, data acquisition card, PC computer and LabVIEW program. From the results, it is shown that, the minimum ignition-delay time for the dual-fuel combustion was observed at stoichiometric equivalence ratio for propane–air mixtures with a pilot diesel fuel or CME. Higher initial temperatures and pressures reduced the ignition delay. Also, the ignition delays of propane–air mixtures are affected by changes in pilot fuel quantities and properties.

Keywords: Dual-fuel engine; Diesel; Propane; Cotton seed methyl ester; Shock tube



...



5. Conclusions
An experimental study on the ignition-delay times of propane–air mixture with pilot diesel fuel or CME was carried out in a shock tube. The ignition-delay times were measured using a piezo-electric pressure transducer, dual mode charge amplifier, National Instruments NI-DAQmx data acquisition card and data acquisition was managed on a computer using a LabVIEW program. Effects of equivalence ratio, initial temperature, initial pressure and different pilot of diesel fuel or CME on the ignition-delay times were investigated. The results obtained from this work are summarized as follows:

(1) The ignition delay period of propane–air mixture for various classes of pilot diesel fuel or CME is at a minimum at stoichiometric equivalence ratio of 1.

(2) In the lean and rich mixture region, the delay period was greater than the stoichiometric condition.

(3) The ignition-delay times of propane–air mixture with CME are greater than the ignition-delay times of propane–air mixture with diesel fuel.

(4) The ignition-delay time linearly decreases proportionally with the increase in both the initial mixture temperature and pressure.

(5) The value of ignition delay of propane–air mixture decreased with increasing the liquid fuel fraction of diesel fuel or CME. It is minimum value at the highest value of liquid fuel fraction of 50% for both liquid pilot fuels.

(6) The ignition delays of propane–air mixture are affected by changes in pilot liquid fuel properties.

(7) The pilot liquid fuel of diesel engine is suitable than CME for dual-fuel engines operation.




Effect of engine parameters and type of gaseous fuel on the performance of dual-fuel gas diesel engines-A critical review
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Author(s): Sahoo BB (Sahoo, B. B.)2, Sahoo N (Sahoo, N.)1, Saha UK (Saha, U. K.)1
Source: RENEWABLE & SUSTAINABLE ENERGY REVIEWS Volume: 13 Issue: 6-7 Pages: 1151-1184 Published: AUG-SEP 2009
Times Cited: 2 References: 45 Citation MapCitation Map
Abstract: Petroleum resources are finite and, therefore, search for their alternative non-petroleum fuels for internal combustion engines is continuing all over the world. Moreover gases emitted by petroleum fuel driven vehicles have an adverse effect on the environment and human health. There is universal acceptance of the need to reduce such emissions. Towards this, scientists have proposed various solutions for diesel engines, one of which is the use of gaseous fuels as a supplement for liquid diesel fuel. These engines, which use conventional diesel fuel and gaseous fuel, are referred to as 'dual-fuel engines'. Natural gas and bio-derived gas appear more attractive alternative fuels for dual-fuel engines in view of their friendly environmental nature. In the gas-fumigated dual-fuel engine, the primary fuel is mixed outside the cylinder before it is inducted into the cylinder. A pilot quantity of liquid fuel is injected towards the end of the compression stroke to initiate combustion. When considering a gaseous fuel for use in existing diesel engines, a number of issues which include, the effects of engine operating and design parameters, and type of gaseous fuel, on the performance of the dual-fuel engines, are important. This paper reviews the research on above issues carried out by various scientists in different diesel engines. This paper touches upon performance, combustion and emission characteristics of dual-fuel engines which use natural gas, biogas, producer gas, methane, liquefied petroleum gas, propane, etc. as gaseous fuel. It reveals that 'dual-fuel concept' is a promising technique for controlling both NO, and soot emissions even on existing diesel engine. But, HC, CO emissions and 'bsfc' are higher for part load gas diesel engine operations. Thermal efficiency of dual-fuel engines improve either with increased engine speed, or with advanced injection timings, or with increased amount of pilot fuel. The ignition characteristics of the gaseous fuels need more research for a long-term use in a dual-fuel engine. It is found that, the selection of engine operating and design parameters play a vital role in minimizing the performance divergences between an existing diesel engine and a 'gas diesel engine'. (C) 2008 Elsevier Ltd. All rights reserved.



6. Conclusion

Researchers in various countries have carried out many experimental works using gaseous fuels as diesel engine fuel substitute in a dual-fuel mode of operation. An attempt has been made here to review the previous studies on dual-fuel concept. The overall observation from these experimental results is that the engine operating and design parameters, namely, load, speed, pilot fuel injection timing, pilot fuel mass, compression ratio, inlet manifold conditions, and type of gaseous fuel play an important role in the performance of dual-fuel diesel engines. Some of the salient points showing the effect of above listed parameters on the performance of dual-fuel engines are listed below.
6.1. Effect of engine load

• The dual-fuel engine performance decreases at part load conditions. There is a minor reduction in power output and higher BSFC for the engines.

• Lower peak cylinder pressure is for a dual-fuel engine compared to the normal diesel engine at a given load condition, which is encouraging since no danger exists for the engine structure. Pressure rise rate (dP/dθ) increases with increase in load and is always higher than that of diesel fuel case.

• Combustion duration is longer compared to diesel operation at low load.

• Lower NOx and drastic decrease in soot emissions with all gaseous fuels. But, at all load conditions, CO and HC emissions are considerably high compared to the diesel case.

6.2. Effect of engine speed

• Thermal efficiency improves with increasing engine speed. Slightly higher equivalence ratios for a given speed condition of dual-fuel engines.

• Maximum combustion pressure is slightly higher than the diesel fuelling level at constant engine speed.

• Pressure rise rate decreases with increase in engine speed and is higher than that for diesel case.

6.3. Effect of pilot fuel injection timing

• An improvement in thermal efficiency is achieved by advancing the injection timing.

• Maximum pressure and pressure rise rate is higher for the advanced injection timing compared with diesel case.

• Advancing the injection timing at medium and high loads led to early knocking.

• Increase in NOx, and a reduction in CO and UBHC emissions with advance injection timing.

6.4. Effect of mass of pilot fuel inducted

• There is an improvement in thermal efficiency and torque output by increasing the amount of pilot fuel.

• Increasing the pilot fuel mass results in higher maximum combustion pressure but reduced maximum pressure rise rate.

• Early knocking with increase in the amount of pilot fuel at high loads.

• Increasing the pilot fuel and reducing primary fuel reduces the knocking phenomena.

• Higher NOx and reductions in CO and UBHC by increasing the amount of pilot fuel.

6.5. Effect of engine compression ratio

• Knock starts earlier when a high compression ratio is used.

• Increasing the compression ratio generally increases the combustion noise.

6.6. Effect of engine intake manifold conditions

• EGR with intake heating improves thermal efficiency.

• Excessive EGR ratio (>50%) causes the deterioration of combustion characteristics.

• EGR with intake heating reduces THC and NOx emissions.

6.7. Effect of type of gaseous fuel

• The engine performance is not deteriorated much with 40% CO2 in biogas as compared to the engine with NG (96% methane). But, 30% CO2 in biogas improves the engine performance as compared to the same running with NG.

• 60% gasoil substitution is possible by gas mixture without knock.

• Overall efficiency falls with gas mixture substitution and adding CO2 affects this more at higher speed.

• Sharp decrease in soot concentration, lower NO, and high HC and CO emissions with increase in NG mass ratio.

• Increasing the mass of gaseous fuel increases the combustion noise and maximum pressure for methane, CNG and LPG.

It seems that dual-fuel combustion using gaseous fuels is a promising technique for controlling both NO and soot emissions even on existing diesel engines with slight modification to the engine structure. The penalty in ‘bsfc’ experienced is partially compensated by the lower price of gaseous fuels. The observed disadvantages, at low engine load condition, concerning ‘bsfc’, HC and CO can be reduced by applying modifications in engine tuning, i.e. injection timing of the pilot fuel. Again, in diesel dual-fuel engines the ignition characteristics of the gaseous fuels are still to be understood and needs more research on it. Thus, in overall, the engine operating and design parameters, and selection of type of gaseous fuel has to be chosen accordingly for an existing diesel engine to run on dual-fuel concept. This can minimize the engine performance, combustion and emission characteristics divergences between the existing diesel engine and a dual-fuel diesel engine.

[c.h.i.e.f]

cannot say anything about what countrys etc etc because its not my place to say but i do know it is known outside australia!

i do not see how if a correctly setup gas system (such as diesel gas) can damage a engine anymore than running 20psi boost in a engine that is designed for max 13psi???

[Dougal]

i do not see how if a correctly setup gas system (such as diesel gas) can damage a engine anymore than running 20psi boost in a engine that is designed for max 13psi???

High boost and diesel fuel doesn't cause detonation or sharp rises in cylinder pressure. This is why the two aren't comparable.

[clean32]

High boost and diesel fuel doesn't cause detonation or sharp rises in cylinder pressure. This is why the two aren't comparable.

LPG and diesel doint cause detonation or sharp rises in cyliner pressure! so whats your point ???

[Dougal]

LPG and diesel doint cause detonation or sharp rises in cyliner pressure! so whats your point ???




Propane - Poor detonation characteristics compared to Methane
Butane - Poor detonation characteristics

Only in marketing literature does lpg not detonate.;)
Maybe "doint" means "do" and we're in agreement.

[c.h.i.e.f]

High boost and diesel fuel doesn't cause detonation or sharp rises in cylinder pressure. This is why the two aren't comparable.

it is comparable... because we were discussing the detremental effects it "may" have on the engine hence why i cant see how it can be frowned upon when it is known that running high boost pressure above recommended engine specs can create problems of a very high degree!

when you say about pre-detonation may it have something to do with the way your engine is setup ? timing(to advanced/to retarded)? boost? fuel delivery? place where the gas was released into the system? regulation of the amount of gas required? etc etc causing this problem???

i cant see how this (registered)product can be allowed to be sold if it may cause engine problems;)

[p38arover]

And Ron , I think he did declare a potential bias when on the 23rd he said his dad owns D Gas tech. ( Unless that was a later edit:) )

Yep, I missed that. I posted before I'd read James' later reply.

In response to the question about the ownership of DGT, James' father, Matt Derrig, is one of the principals of the company.

[Dougal]

it is comparable... because we were discussing the detremental effects it "may" have on the engine hence why i cant see how it can be frowned upon when it is known that running high boost pressure above recommended engine specs can create problems of a very high degree!

when you say about pre-detonation may it have something to do with the way your engine is setup ? timing(to advanced/to retarded)? boost? fuel delivery? place where the gas was released into the system? regulation of the amount of gas required? etc etc causing this problem???

i cant see how this (registered)product can be allowed to be sold if it may cause engine problems;)

Isuzu make a B series marine engine (the 4BG1T) which runs more than 20psi boost. Marine engines are a market where reliability is rather important. Every marine engine brand has high boost, high performance diesels, it's been well proven.
On road cars BMW run more than 42psi boost in their highest tune 3 litre diesels (200kw, 600Nm). Their competitors aren't far behind.

Where I'm going with this is the risks and rewards of high boost are very well understood, you can buy engines which run very high boost and they come with the standard warranties.

The risks of lpg fumigation aren't well understood and it isn't well researched. Engines have been damaged, but also people run it without apparent problems. There isn't enough understanding to say this amount is safe and this amount isn't. But all the engine manufacturers stay well clear. Not one manufacturer has produced or advocated such a system.

[lambrover]

it is comparable... because we were discussing the detremental effects it "may" have on the engine hence why i cant see how it can be frowned upon when it is known that running high boost pressure above recommended engine specs can create problems of a very high degree!

when you say about pre-detonation may it have something to do with the way your engine is setup ? timing(to advanced/to retarded)? boost? fuel delivery? place where the gas was released into the system? regulation of the amount of gas required? etc etc causing this problem???

i cant see how this (registered)product can be allowed to be sold if it may cause engine problems;)

You don't have to look that hard to find products that are aloud to be sold but are bad for the user and others. Take bongs for smoking pot, how is it that you can you sell them but not use them, they will fit bigger tyres to your car but they shouldn't, lots of legitamant companys sell stuff that is not surposed to be used for on road use my steering damper from tough dog say that on the packet.