Long range tank vs. LPG Dual fuel set up

Submitted: Friday, Jan 20, 2012 at 19:52
ThreadID: 91345 Views:3221 Replies:7 FollowUps:1
This Thread has been Archived
G'Day all,
My little 4WD (Pajero io) has a small main tank of about 55 litres. On an easy highway run, this will give me a range of about 450kms. Although not bad, I fear that heavy going along with a bit more than just passenger load will significantly impact that range.

Cargo space is pretty limited so carrying jerry cans is not an option, plus I wouldn't put them in the car...(that's another topic of debate there I'm sure) or on the roof.

So, given my situation, what would you suggest? Fit a second tank of about 40 litres (ULP) or run a duel fuel set up? I understand that some will say that dual fuel adds complexity into the system, but it also eliminates the risk of being stranded by bad fuel or a dodgey fuel pump.

With a simple exhaust mod, I can free up a pretty big area under he car, so that's the intended home for it.

Thoughts and opinions most welcome.

Back Expand Un-Read 0 Moderator

Reply By: Member - Tony V (NSW) - Friday, Jan 20, 2012 at 20:21

Friday, Jan 20, 2012 at 20:21
Fab 72

There are a few LPG haters out their, some petrol purest and many diesel lovers.

Over the past 24 years I chose to have dual fuel 4WD's.
Originally from Victoria,where LPG has been embraced for many years.

I had the following,

1989 Maverick on LPG from new- 250,000 kms new valves at 150,000 kms.
In 1999 I purchased a 2nd hand 1994 80 series on LPG, 108,000 ish kms traded at 198,000 in 2004.
LC 100 series, V8 on LPG from new, currently 225,345 kms.

I have traveled much of Australia, with carefull management and utilising the LPG as a usable 80ltr sub tank, I have not had any fuel issues.

Considering most people spend the majority of their time within 100kms of civilisation, I think dual fuel is a good alternative and works for me...

AnswerID: 475537

Follow Up By: Member - Paul B (WA) - Saturday, Jan 21, 2012 at 16:18

Saturday, Jan 21, 2012 at 16:18
At the risk of having my head bitten off again by the "LPG lovers", my experience with LPG was very bad.

I would not want you go into this without thinking there is not the potential for immense problems with LPG conversions on existing systems.

It is an added complication that for me, turned a beautiful car car into a lemon. If that wasn't bad enough I had several mates all say to me afterwards, "I told you!"

As I said in Thread 91268 the other day, I wouldn't touch LPG again for all the tea in China, but you're apparently not allowed to say that here.

This "LPG hater" has bitter experience on my side - and not only my bitter experience either.

But you go for it, if it's what you want.

Good luck.
FollowupID: 750554

Reply By: vk1dx - Friday, Jan 20, 2012 at 21:39

Friday, Jan 20, 2012 at 21:39

One of our sons had a Pajero with dual fuel and like mentioned above they remained within easy reach of both petrol and LPG. Then Dad (me) and his elder brother got a couple of diesels. When planning for drives like around the Kimberley via the Tanami and up around the back blocks of Cape York he was in a fix with LPG. He now has a diesel.

If you wish to go to remote areas consider the availability of LPG. If you stick to populated areas then maybe dual fuel is the way for you.

Just giving the other side of the issue.

AnswerID: 475545

Reply By: Brian Purdue - Friday, Jan 20, 2012 at 23:02

Friday, Jan 20, 2012 at 23:02
About 30 years ago I had a 2 door Range Rover. The previous owner had fitted TWO extra tanks between the side rails of the chassis and the drive shaft.One each side of course. From memory one held about 40 litres and the other about 35 litres. The main tank held 80 (?) litres. (16 gallons.) There was a three way tap fitted in the floor well at the rear seat. Gave me an excellent range and was never any trouble. Had to do a few clicks on the main tank and then change to the lesser tanks because they were not connected to the fuel gauge.
AnswerID: 475550

Reply By: splits - Friday, Jan 20, 2012 at 23:07

Friday, Jan 20, 2012 at 23:07
I used gas powered cars for 18 years but mainly for commuting to and from work. There were two long trips from Sydney to far north Qld and two to Tasmania during that period plus a five year period living in rural NSW. I now own a diesel. I would use gas again but only in major city areas. The much higher prices in the bush reduce savings so much it would be hard to do enough ks to justify the cost of the conversion.

The first car was a 12 year old 504 Peugeot. The exhaust valve seats lasted 20,000 ks. After fitting harder ones, it went another 400,000 ks over the next 10 years without any problems. It was dual fuel but I rarely if ever switched it over to petrol.

I did not like having something in the car that I did not know anything about so I completed a 2 week full time course at Ultimo TAFE in Sydney and got my own installation licence.

After scrapping the Pug I converted a Gemini that had been in the family for a few years to straight gas and did 180,000 ks over three years. It immediately started getting too hot. A new triple core radiator and a different thermostat did not fix it but making a fibreglass fan shroud did. There were no problems with valves or anything else. The conversion cost with a new tank and a few of the Peugeot parts was $700.

Next came a Holden powered Mitsubishi ute. The engine was rebuilt to suit straight gas from day one. It only did 80,000 ks over 5 years because I was not commuting to work any more. It cost me $600 to convert it but if I had to pay the usual conversion costs it would not have been worth it.

The conversion cost is a major factor. Even with Govt. rebates, the latest computer controlled systems are expensive. You must be certain you are going to do enough ks to make it worthwhile.

Gas can make your engine and exhaust system last longer but saving money is the main reason people use it.

When we started the TAFE course, the teacher wrote the then current price of gas and petrol on the top of the blackboard. Gas was 23 cents per litre and petrol about 50 cents from memory. Every time we discussed a disadvantage with gas, and there are plenty of them, he would point to the 23 cents and that justified it.

When calculating the expected range of gas in your car, don't forget the tank only holds 80% of its water capacity. That means a 100 litre tank will hold a maximum of 80 litres of liquid gas. This is to allow for expansion which is 2.5 times that of petrol. The tank is also 3 mm thick and fairly heavy. The older systems will use about 12 to 15% more gas than petrol to go the same distance but I think the current systems have reduced that difference considerably. It will all depend on the age of your car and the type of ignition and fuel system it has.

If you decide to do it, make a few inquires first with gas conversion companies, Pajero forums on the net and gas equipment manufacturing companies like Impco for example. Make sure your engine is suited to it. Find out how it will perform on gas with the engine still tuned for petrol. See if anything has to be modified like the cooling system, ignition etc.

These were all issues years ago but may be different now. Many cars had valve problems but now anything designed for unleaded is usually ok. A blue 202 Holden for example was as dead as can be on gas but replacing its camshaft with a stock one from an earlier 186 model made the world of difference.

Gas burns slower than petrol so advancing the ignition timing at idle was the way to go. What you added at idle had to be taken off at maximum revs though or it would over-advance at cruising speed. This made a big difference for gas but when you switched back to petrol, the engine would ping its head off. This meant dual systems were a compromise with gas performance the one that had to suffer.

The latest factory systems may allow for this in their computer designs but your petrol computer, if you have one, may not be reprogrammable. If it is then the conversion cost may be higher.

Have fun and I hope it all works out ok.
AnswerID: 475553

Reply By: Batt's - Saturday, Jan 21, 2012 at 19:37

Saturday, Jan 21, 2012 at 19:37
G'day fab I'm in Mackay and I had a GQ patrol and had LPG put on it 6yrs ago a 90ltr tank which held 80 to 85lts of gas depending on the weather hot or cold the supplier and how fast it filled up some fast some slow probably meant the servo's tank was low anyway I wouldn't get LPG again even though it's cheaper than petrol .Mine used about 30% more LPG than petrol and apparently you can get problems with poor LPG . I think sticking with one type of fuel is the better option for me after trying it even though the patrol's come with hardened valve's I was still advised to put some upper cylinder lube in occasionally. You can buy ULP just about everywhere unlike LPG when travelling big distances out west. Next time I'll just do some mods to help fuel ecconomy,snorkle and exhaust system and stick with straight ULP I've had 4 petrol and now my 5th diesel 4wdrive. How much LPG can the tank hold for the pajero and is it worth the cost I say go for the 40ltr ULP tank which will give an extra 300km plus range
AnswerID: 475604

Reply By: Best Off Road - Saturday, Jan 21, 2012 at 23:44

Saturday, Jan 21, 2012 at 23:44
Modern "injected" LPG is just superb. Smooth and powerful on either ULP or LPG.

However for it to be cost effective you need to spend time doing the numbers. My business ute is a 4L V6 Ford Courier. It guzzles fuel, but on LPG it is cheaper to run than any diesel ute. The recovery cost over running on just ULP took about 10 months.

Your IO seems to be fairly fuel efficient. I'd suggest it would take a long time for you to break even. It's all a numbers game.

AnswerID: 475629

Reply By: Fab72 - Sunday, Jan 22, 2012 at 21:26

Sunday, Jan 22, 2012 at 21:26
Thanks for all the replies everyone...some very interesting reading.

I guess I was looking at it from the perspective of increasing my range, not really from a fuel saving perspective (the thing is cheap to run already).

I've had 3 cars on dual fuel in my life and have seen dramatic improvements to the systems over the years. I'm also a licenced fitter so I'd save a few dollars on the conversion.

I remember buying LPG in Coober Pedy once and the cost per litre plus the efficiency loss meant that I saved nothing over using straight petrol. However in the same car (VE Commodore with factory dual fuel), on the return journey from Alice Springs, I filled both tanks in Alice and got all the way to Port Pirie without adding fuel. The range is what I miss in the io.

Weighing up all the pros and cons, I'm actually leaning towards a 40-50 litre tank for ULP out of an old ute of some sort. Utes usually have more square/retangular tanks and if I get a Mitsi one, the resistance values for the fuel sender unit might be the same as my original tank meaning that through a switch, I should be able to access fuel level readings for both tanks through my standard gauge. I want it to appear integrated and not some slap together add on.

Thanks.... I think I've just talked myself into taking the ULP path.

AnswerID: 475731

Sponsored Links