Is LPG still worth it?

[David V]

My understanding is that some petrol stations are removing the LPG pumps due to less patronage.

But my biggest reason for steering clear is my mechanic. He said 'LPG is for BBQ's, not engines'. The system in my old Falcon ran well, but I wouldn't convert the Pajero, not these days.

[disco stu]

Bit of an old thread, but can't help myself.

I've run LPG on our family cars for years, and made great savings with it when it was cheaper. I even profited a few times with the rebate, installing second hand systems onto cars, paying for the "install" (they hooked up the gas lines and did the checks) and then claiming the rebate. Boy the price of installation rocketed up when they introduced the rebate-had to laugh at the comment in here about an industry pricing themselves out of the market, my exact thoughts as the price hasn't fallen back down to what it was pre rebate.

I loved the governments solution to the fuel price issue-we will just tax LPG!

I've now bought myself a pajero on LPG, unregistered while I do some work on it. I'm currently running around in my other cars on petrol at the moment-86c/L locally for LPG, and fuel around $1.15/L. I was initially keen on a diesel, until I noticed that most of the cheap diesel pajero's had fuel pump issues and it was $1500+ for a fuel pump. At $1.50 for diesel its going to take a while to earn that money back. Plus this car was close and I wouldn't need to tow it home over the blue mountains.

I guess I'm banking on the price of LPG staying pretty similar while I assume petrol will go back up to $1.50ish/L. Currently all cars have a mixer set up, and I just found a brand new second hand LPG vapour injection kit for $300 which I will install while I have the engine apart (Stag brand). I'm hoping that brings the efficiency of the gas closer to petrol and saves a bit more running cost in the longer term.

So I guess it all depends on what the fuel price does in the longer term. It's never really stayed this low for so long before......

Would I pay for an LPG installation with the current installation prices and fuel prices-no chance. Use it you've got it

[El_Freddo]

LPG is redundant, no real savings, shorter engine life, extra maintenance and poor range, I believe they're trying to price it out of the market so people move away from it......just my opinion.

Dunno how you get reduced engine life. We ran our (now) old 89 efi Range Rover on LPG from 68,000km through until it was retired at about 780k km. The engine was “rebuilt” at 500k km with the onlywear being shown on the cam lobes and the cam chain plastic silencer pieces. The rings, pistons, cylinders and heads were clean as a whistle. It did a lot of towing.

Went really well on gas too - the trick is to advance the timing.

Gas injection is even better again.

But as mentioned, unless you’re really keen to have gas, you’re probably better off putting your money into a long range tank and fill up when it’s cheap. You’d probably make your money back quicker doing this if well disciplined.

My 20cents worth anyway.

Cheers

Bennie

[nj swb]

Dunno how you get reduced engine life.

I think it comes down to the design / construction materials of different engines as to how well they handle LPG, which I think has higher combustion temperatures? I think there is also a minor lubricity issue i.e. LPG differs from petrol somehow that affects engine life - probably more an issue with carburettor engines than multi-point injected? I recall something about "upper cylinder lubrication" kits for LPG conversions?

Years ago, Mitsubishi advised owners against fitting LPG to the 12 valve 6G72 engine (3 litre V6), but considered the 24 valve version OK, along with the 6G74 engine. Something to do with valve seat recession?

We've had a few "discussions" on here - those who fitted LPG to a 12 valve 6G72 against Mitsubishi's recommendation and had no issues, and those who had subsequent head failures. So I think it's fair to say that LPG might lead to reduced engine life, depending on the engine, and/or the luck of the owner?

[erad]

I have had 5 vehicles running on LPG. Two of them were TM Magnas - definitely NOT designed for LPG. Both did over 120000 km on gas, with no obvious difficulties regarding valve recession. I had a Range Rover and that did 230000 km on LPG, but I had Flashlube valve saver fitted to it. Not sure if that worked or not, but when I pulled the engine down because of a head gasket problem, I checked the valves and they looked fine. I didn't even try to lap the in again.



With the Rangie, when I stripped it down (320000 km total distance travelled), I could stills ee the original honing marks in the cylinder bores. So much for causing extra engine wear when running on LPG...


I then had a TF Magna and a NL Pajero, both on gas. The Magna gave me problems with the petrol system - the filter became choked with a solid red mud-like substance. The Pajero petrol system I had rewired so that the pump would not run when it was running on gas (95% of the time). No such problems with the Pajero petrol system. There were plenty of problems with the ignition system though (backfires etc) and it took years to sort that out. Again, at 235000 km when i had the Pajero engine stripped (because of my stupid mistake), I could clearly see the original honing marks from the original engine build. The piston ring gap was within original factory tolerance on all the pistons. The engine was as clean as a whistle inside.



So I don't see LPG as causing any additional wear on the engine. As for the economics, that is a different story. The price of LPG used to be kept at about 40 cents/Litre less than petrol. That was OK when petrol was 80 cent per litre or so, but now, the difference is probably not enough to overcome the additional fuel which you use when running on LPG. When comparing costs to diesel, I used to reckon that if LPG was less than half (or maybe 60%) of diesel, I was in front. I think the same balance still applies. I now have a NW diesel, and I know for sure it costs more to run that my old NL Pajero, but there is no way I would go back to the NL, even thoguhit was a really top car.

[disco stu]

I was confused about that comment as well, but now I've remembered the valve issues in some engines. They "reckoned" that anything designed for unleaded was fine for LPG, but I don't think that was the case, well for earlier cars post leaded petrol disappearing. I killed a valve on my 98 camry, possibly due to running LPG.

I don't think there would be any issues in any modern engines. Obviously direct injection wouldn't have any fuel lubricating the valve and seat and they seem to be alright.

The valve issue is the only thing that they could be referring to for increased wear and tear, and that is only on some engines in original spec

[erad]

Interesting comment about valves and LPG. When I bought the TF Magna and the NL Pajero in 2000, it was my intention to have them both on LPG. The Magna was bought second hand - it was an EPA car before. The Mitsubishi blurb for the Magna at the time said that the base model was not compatible for LPG. I phoned Mitsubishi in Adelaide and the guy asked for the engine number. I gave it to him and he told me that my engine (a 3.0 L 24 valve) was suitable for LPG, but the base model was not. My TF Magna was an Advance model and had a suffix 'A' on the engine number. Subsequent 3.5 L Magnas were all LPG compatible, as was the NL Pajero engine. I find it hard to imagine that ALL unleaded engines would not have been LPG compatible, but obviously this was not the case then.

[disco stu]

That's interesting. Do you know specifically what the difference was? I would assume valves/seats, but......

[erad]

That's interesting. Do you know specifically what the difference was? I would assume valves/seats, but......

Sorry - I don't know what the difference is, but I vaguely recall someone somewhere talking about differences in the ECU. I suspect that it may be more related to where the engine was made - maybe the base model (non LPG) engines were made overseas and the LPG compliant models were made in Australia? If this is the case, it tends to lean towards different valves or valve seats. All I know was that the Mitsubihsi guy I spoke to told me that it was my lucky day when I gave him the engine number and that was when he explained about the 'A' suffix being LPG compliant.