Diesel/Gas. pros and cons?
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bods
Member
Hmmm....
Lets just say diesels don't "run" on gas...
The gas is fed into the intake system to give the engine more power... it is an air/lpg mix fed in, then diesel injected and you get a bigger bang...
You may get slightly more range due to the engine not working as hard, but not a great deal, especially if you have a heavy foot...
Lets just say diesels don't "run" on gas...
The gas is fed into the intake system to give the engine more power... it is an air/lpg mix fed in, then diesel injected and you get a bigger bang...
You may get slightly more range due to the engine not working as hard, but not a great deal, especially if you have a heavy foot...
As described, LPG is mixed in with the incoming air and the combustion process is more pronounced - they say it's like 30% more. If you use that to assist a sedate driving style, you will get better economy. If you're trying to break 2:07:48 on the mountain you'll certainly show that you have some ponies around the place, but your economy won't improve a whole lot (at all, if you're a real leadfoot).
Combustion temps will rise a bit due to the nature of the beast - if you ask it for more burn, you are going to get more burn and more burn = more heat.
Other than that, when the gas bottle runs out your car will simply return to normal.
Combustion temps will rise a bit due to the nature of the beast - if you ask it for more burn, you are going to get more burn and more burn = more heat.
Other than that, when the gas bottle runs out your car will simply return to normal.
bods
Member
Just one thing to keep in mind with water/meth injection, as Tony mentioned above, when the lpg runs out you simply return to normal. Generally with gas you don't need it tuned.
With water/meth, because it is used to cool the charge air temperature, normally boost is increased and then fuel increased to match. This can cause problems if you run out of water/meth in the bottle.
The advantage of it though is you can buy or make a simple system that you can fit yourself at home, so a lot less cost than having lpg fitted. You can also run straight water if you haven't got any methylated spirits to top it up with.
Hope that helps a bit
With water/meth, because it is used to cool the charge air temperature, normally boost is increased and then fuel increased to match. This can cause problems if you run out of water/meth in the bottle.
The advantage of it though is you can buy or make a simple system that you can fit yourself at home, so a lot less cost than having lpg fitted. You can also run straight water if you haven't got any methylated spirits to top it up with.
Hope that helps a bit
Another difference between LPG and water/meth injection is what it does to combustion. Water is a combustion dampener - it cools the process (which is good, and as steam it promotes cleaning) and meth flash-burns once it's ignited. The diesel has to ignite first, but once it's starting to burn, the metho will burn VERY quickly. Because this is happening just as the piston is moving off TDC (as long as you aren't using a chip that advances timing) it will give the piston a decent kick along even though the angular forces on the crankshaft are pushing hard against the bearings - you get the greatest actual power when you're pushing against the piston and the piston is halfway down its stroke, which makes the big end sit at 90 degrees to the shaft so ALL of the force is directly translated into rotation. If you're running meth, don't advance the timing too much!
bods
Member
Since when..? Or is that a state specific thing? In wa you go over the pits when its fitted and the only inspection is for the tank to be retested every 10 years...
State specific.
Nsw have annual inspections any way, ACT you get one ONLY if you have LPG.
Not sure in QLD - I found lpg and specifically diesel gas not as cost effective as I thought never bothered again.
bods
Member
Fair enough. .. I can see why it isn't really worth it... especially when you can fit a water/meth kit at home...
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G'day,
More information please.
Years ago I had some Petrol/LPG vehicles, the cylinders needed pressure testing every 5 years. I believe that is still the case.
I've also been told there are some exemptions at least for those living in remote parts of QLD.
(Others posts added while I was preparing this post)
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I posted up all I know.
I had Dgas in a 2000 4.2 Gu Patrol.
With it I lived in ACT and NSW.
ACT did not have inspections UNLESS you had LPG.
NSW has an annual inspection for rego and an extra one at a LPG installer for the GAS.
Traded the wagon for a 02 GU Ute which I fitted with a Disco Potato boost compensator and slightly modified fuel pump metering rod. I got better performance, better economy and LOTS more power, and ran a LOT cooler on the EGTs.
Best investment ever! A perfect match for the 4.2 diesel engine.
I had Dgas in a 2000 4.2 Gu Patrol.
With it I lived in ACT and NSW.
ACT did not have inspections UNLESS you had LPG.
NSW has an annual inspection for rego and an extra one at a LPG installer for the GAS.
Traded the wagon for a 02 GU Ute which I fitted with a Disco Potato boost compensator and slightly modified fuel pump metering rod. I got better performance, better economy and LOTS more power, and ran a LOT cooler on the EGTs.
Best investment ever! A perfect match for the 4.2 diesel engine.
happy john
Member
"Chatrock" a member here has fitted gas injection to his immaculate brown d22 zd30. He is very pleased and has lugged his van all around Australia. When I last spoke to him he was very pleased with the setup.
happy john
Member
G'day
Quote Old Tony: "Combustion temps will rise a bit due to the nature of the beast - if you ask it for more burn, you are going to get more burn and more burn = more heat."
From what I have read things should generally run cooler.
If I relocate the spare wheel I will have room for a 60-70L usable LPG Cylinder. that will last 3 tanks of Diesel. This will suit my needs.
Quote Old Tony: "Combustion temps will rise a bit due to the nature of the beast - if you ask it for more burn, you are going to get more burn and more burn = more heat."
From what I have read things should generally run cooler.
If I relocate the spare wheel I will have room for a 60-70L usable LPG Cylinder. that will last 3 tanks of Diesel. This will suit my needs.
I have my doubts about the "running cooler". There's a thread on this forum here where it's discussed, with pointers to other threads.
I'd be very interested to see results of a with-and-without on a dyno with only minutes or even seconds between runs (providing identical resistance and atmospheric conditions to remove those as factors). Primarily I'd be interested in EGTs, which would dispel the myths once and for all.
I'd be very interested to see results of a with-and-without on a dyno with only minutes or even seconds between runs (providing identical resistance and atmospheric conditions to remove those as factors). Primarily I'd be interested in EGTs, which would dispel the myths once and for all.
