LPG economy rates
- Thread starter Haaks
- Start date
GUnka
Well-Known Member
LPG will never give anywhere near the economy you will get with petrol. You make no mention of what sort of driving you were doing for that 300km. Considering you're driving a brick with another brick on the roof 28l/100km is probably around the mark for a dual fuel older style lpg system on a motor that am sure has quite a few k's under it's belt.
GUnka
Well-Known Member
Haaks
New Member
Yep, fair enough. A lot of those kms were in horrendous Melbourne traffic. I'm sure I would get better mileage on the open road
Haaks
New Member
Riding on 33 muddies, 3inch lift. Darche Panorama on the top, quite low profile for a rtt
GUnka
Well-Known Member
Don't bet on it unless you plan on driving at 80km/hr. Pushing a double decker brick at 100km/hr+ will probs use more fuel than just driving round the city.
I get about that with a 4.6l V8 towing a 1.5t caravan.
Very few LPG places actually tune LPG properly. I use to take mine to one of the largest LPG places in Melbourne and have it tuned on a dyno. I use to do this at least once a year. But they stopped doing dyno tunes on a Saturday and I could not make it during the week. So I went and purchased a good quality wide band O2 meter so I could tune it myself. I then found that the LPG experts had never set up the system properly. I tuned it properly and got a big increase in power and a lot better fuel economy.
What I found is that every LPG place I have come across, and I only go to places with very good reputations and I am generally impressed with the quality of work, always tune the things too rich. LPG is not like petrol where the more you pour in the more power. Power on LPG actually goes backwards at a rapid rate when running rich.
So my advice to anyone on LPG is to go and buy a good quality wide-band O2 gauge and tune it yourself in the driving conditions that you encounter. Even though they are a few hundred dollars, they will pay for themselves in better fuel economy and increased power.
It was along time ago now. I am pretty sure it was around $100 at the time.
That is why you are best off modifying any open loop system to a closed loop system so it will self adjust.
The best mixture to run it at is the correct one. As you have said, run it too lean and there is a possibility of engine damage. Run it too rich and you sacrifice power and economy. Just right is the best.
GUnka
Well-Known Member
A closed loop old style mixer type LPG system.... who supplies these? can you fill us in on how these work. Or a are you talking about the much more expensive aftermarket gas injection systems and or OE LPG only?
There are number of systems that will change your open loop to a closed loop. It depends whether you have a impco mixer that has the power adjustment built into the mixture or the more common type where the power control is in the line between the convertor and mixer. The later is more simple where the power adjustment is simply replaced with a solenoid that adjusts its mixture based on a small ecu and O2 sensors in the exhaust. For the impco mixer, like mine, it involves a small solenoid that increases or decreases the vacuum applied to the mixer diaphragm to adjust the mix.
You can see the various units here; http://www.alternatesolutionsgroup.com.au/LPG-Fuel-Processors.htm Mine is the CP401, the second one on the link.
I do not like the vapour injection systems and would not put one on my car.
You can see the various units here; http://www.alternatesolutionsgroup.com.au/LPG-Fuel-Processors.htm Mine is the CP401, the second one on the link.
I do not like the vapour injection systems and would not put one on my car.
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GUnka
Well-Known Member
What are the $$$$ for these type of systems?
I only posted a link to one brand. There are many similar systems out there. I am sure that they all vary in price.
GUnka
Well-Known Member
I didn't see any prices listed. I just think when you add up all the pro's and cons and with LPG now having excise on it and the cost is around 70% of petrol that the days of LPG being a cheaper alternative are over. But hey, that's just my opinion.
For years I tried to get an open loop system tuned correctly. It is basically impossible. So the main benefit is that I could actually tune the system, this was a significant benefit to my sanity. I also obtained a lot better fuel economy. Due to the amount of oil in LPG, the systems get clogged up and the tune keeps on changing over time. Just like people who remember having points in their ignition distributors. The change to a closed loop system is light converting a points distributor to an electronic ignition, it keeps the motor in tune longer.
The basic issue with tuning an open loop system is the air intake temp. I could have it tuned properly and then go up the snow. The cold air would make the system run very lean. So do you richen it up and have lack of power for the other 99.9% of the time you drive it.
I had vents in my bonnet. The air intake was close to the vent on the passenger side. If it was a warm day and the wind was coming from the passenger's side, it would run at the right mix. If the wind was coming from the drivers side, the air would get hot crossing over the motor from the driver's side vent to the air intake on the passengers side and the mixture would run rich.
So depending on air temp, the direction of the wind and what altitude you were at made reasonable differences to the tune of the motor. So the tune was always a compromise to try and not let the system get into a situation that could damage the motor. That is why all the LPG tuners set them up rich.
So with a closed loop system I only have to worry about setting up high throttle mixtures. Whether the mix is high 12's or low 13's does not worry me that much at WOT and it is sucking that much air that the temp is not as critical.
As you can probably tell by now from my posts on this forum, I am a perfectionist. I have to get the things as best I can (within financial limits). I therefore research the hell out of anything I am looking at and then follow it up with a lot of testing. Never being able to get the tune correct on a open loop system use to drive me nuts.
That is why that most of the LPG convertors have gone out of business since the Government stopped the conversion subsidies.
On a trip it costs me around 10 cents per kilometre in a V8 4wd. In my Falcon wagon it costs around 5 cents per kilometre. It would take a long time to pay off a conversion these days, but you have to take into account other factors. For example a second hand petrol 4WD is usually many thousands of dollars cheaper than the equivalent diesels. You can either spend part of that saving on a LPG system and have cheap running costs and longer motor life, or on the extra cost of petrol. Either way you will be better off financially that buying the diesel version.
There is also the illogical factor. For example, my wife Disco on LPG costs twice as much to run as my falcon. My Rangie ute on petrol costs twice as much as my wife's disco to run. So which vehicle do I use on a longer trip. I want to take my ute. So I paid to have the ute converted to LPG. It was a once off cost, but now I use it more.
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80lover96gxl
Moderator
22 lp100, 4.5 80 series, 33"muds,3"lift roof rack, bar, winch, draws yada yada yada.
Old style mixer system tune advanced 2 degrees on dizzy, without this it pings its head off.
Heads ****ed after 10yrs on lpg but still goes ok, 300k on engine.
Gunna wack a new head on it and see Iuf i can get 600k out of the ol girl.
Old style mixer system tune advanced 2 degrees on dizzy, without this it pings its head off.
Heads ****ed after 10yrs on lpg but still goes ok, 300k on engine.
Gunna wack a new head on it and see Iuf i can get 600k out of the ol girl.