Diesel Gas

**clean32** · 15th March 2010, 10:13 PM

Originally Posted by 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?

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** · 15th March 2010, 10:35 PM

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

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

.

**Dougal** · 16th March 2010, 03:28 AM

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

Originally Posted by bee utey

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.

Originally Posted by bee utey

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** · 16th March 2010, 05:56 AM

Originally Posted by Dougal

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.

Originally Posted by Dougal

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** · 16th March 2010, 06:46 AM

Originally Posted by p38arover

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

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

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

**p38arover** · 16th March 2010, 07:01 AM

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** · 16th March 2010, 08:20 AM

Originally Posted by Dougal

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** · 16th March 2010, 09:19 AM

Originally Posted by p38arover

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** · 16th March 2010, 10:34 AM

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

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** · 16th March 2010, 10:27 PM

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

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