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is it still true that lpg etc makes the engine run hotter and might contribute to an early failure of the motor?

It is true that LPG fuel has no lubricating properties like petrol, therefore runs drier and hotter. However most cars from start 1990's? onwards have hardened valve seats and other componentry suited to LPG from factory (but not all)...this used to be be the main problem in the old days which meant you had to recondition your cylinder head/s to suit the LPG (i've done this before to my early Holden V8 dedicated LPG motor.)

There are additives you can buy and add to your petrol tank on duel fuel cars to help with upper cylinder lubrication if your head/engine is not 100%compatible...

I understand that the RB25DET is a fully compatible LPG engine.

My dedicated LPG Stagea has never ever gone over the 1/2 temperature mark on the gauge, even in 40 degree heat in Summer, sitting in traffic!

The very important things to remember with LPG is to have your cooling system and electrical systems (coil packs for RBDET's) in top condition. If your coil packs are on their way out running on petrol.....you will see a massive negative effect on LPG mainly due to more spark energy required to ignite the fuel.

Running on LPG does not destroy your engine if your engine is LPG compatible, infact it runs cleaner with less carbon build up, oil is cleaner etc etc.

I could go on.....

Those who have made the switch, I congratulate you,

those that are contemplating the idea I encourage you to find out more FACTS not OPINIONS.

What LPG system are you actually running?

I'm wanting to run a liquid phase injected setup once I've got other things sorted. Preferably the one from *this place* which should fit my budget and performance needs, although I'm still looking around at others.

I guy I work with has a Merc 560SEL 89 model. Car is in now getting converted to gas. Cost is $3000, the government rebates $2000 at the moment. So you are out of pocket $1000.

Unleaded in QLD is $1.50, gas is $0.70 so that saves you $0.80 per litre

He uses currently 80L per week of unleaded, which will save him approx $64 per week. So he will get his $1000 back in 16 weeks!

LPG does not get the same economy as unleaded, so that will need to factored in. So it may take a bit longer to get his money back, but definitely under 6 months and worth considering

Based on current LPG and petrol prices, 4 months is not an uncommon payback if you drive a lot and your out of pocket conversion costs around $1000.

My payback was calculated about a year a go before the conversion to be about 9 months....with the increase difference between the cost of the two fuels between now and then, my payback was actually 6 months...

What LPG system are you actually running?

I'm wanting to run a liquid phase injected setup once I've got other things sorted. Preferably the one from *this place* which should fit my budget and performance needs, although I'm still looking around at others.

You can check out my details here;

http://www.skylinesaustralia.com/forums/Lp...-2-t226938.html

I thought about the (SGI) LPG sequential gas vapour injection technology however didn't go for it as I knew the LPG Liquid Injection technology would be just around the corner!

LPG Liquid Inject. http://www.lpgli.com/lpg.html

I spoke with these guys a while back when I was researching and planning the conversion. They said that the system was still in development. From their website, looks like it is still not available.

The only LPG Liquid Injection system that I know is going to be made available in the next few months is from....

http://www.australianlpgwarehouse.com.au/

JTG Italian LPG Liquid Injection system...supplier claims only 5% loss in fuel consumption compared with petrol and increased efficiency "Like turning a 4.0 litre engine into a 4.5 litre engine".

Not sure how long it would be until available for performance and forced induction applications but maybe worth contacting them....

  • 4 months later...

Seems to me the biggest problem with lpg is where to put the tank.

Im a big fan of lpg having owned 4 vehicles in the past with it. Every car I had with gas was 40% cheaper to run than on petrol. Now have a stag and even though i love it, the fuel bills are cruel.

Last car was a vl on gas. ( Cheaper to run than the wife's echo) Tank was a torroidal (doughnut) in the spare wheel space. Big improvement on the great blob inside the cargo space option. Problem was it still sat about 60mm proud of the floor and used to shit me as well. Also stags use a space saver spare so nowhere near the depth in the spare wheel well as a full spare space.

What if the petrol tank were replaced with a manifold tank, then a small petrol tank be manufactured and jammed in somewhere so it could run duel fuel?

That would leave the cargo bay uninterupted.

Also something no-one who sugests dedicated lpg has mentioned........its a real piss off having to get towed to a fuel station if u run out of gas. You cant go for a jerry can of lpg........ Been there done that. Also found myself in the situation of not able to get it in a particular area or the delivery didnt come etc. Then you're walkin.

Edited by deanoss
It is true that LPG fuel has no lubricating properties like petrol,

Its only the lead in pre-unleaded petrol that has any lubricating qualities. LPG is actually better for your motor. Petrol vapor contaminates the oil on the cylinder walls in petrol engines, marginally reducing its quality and requiring you to change it more often to offset the effect. Obviously no such effect with LPG.

therefore runs drier and hotter. However most cars from start 1990's? onwards have hardened valve seats and other componentry suited to LPG from factory (but not all)...this used to be be the main problem in the old days which meant you had to recondition your cylinder head/s to suit the LPG (i've done this before to my early Holden V8 dedicated LPG motor.)

Unleaded was introduced in 1986, so all engines from that point on have hardened valve seats to cope with unleaded, and therefore will also cope with LPG. Since other countries were running unleaded before Australia some earlier engines also have hardened seats.

The interesting thing with this conversion is that there is not the typical loss of power associated with an LPG conversion.

Unleaded was introduced in 1986, so all engines from that point on have hardened valve seats to cope with unleaded, and therefore will also cope with LPG. Since other countries were running unleaded before Australia some earlier engines also have hardened seats.

i aggree with you there but still some cars didnt have the hardned valves, because alot of commodores have the valve saver fluid when theyare converted to gas and im talking about later modles like vy and earlier. im not sure about the alloy tecks but i know the earlier ones needed it.

  • 4 months later...
People keep putting crap on LPG systems but I don't know why. I drive a VT wagon on LPG for work and it gets better dollar for dollar k's than my wife's current model Ford Fiesta buzz box.

Yeah Im with you. My VL was cheaper to run on gas than the wifes echo.

I guess its mostly because these are premade kits. The one Mark put in his GTR runs 2x4 bank of gas injectors (1 unused on each). We mounted them on the loom cover directly above the inlet manifold so each run is fairly short.

Vapour injection isnt all its claimed to be , through my work we are seeing injectors block up due to oil and garbage in the lpg filling the vapouriser with oil wich intern goes into the injectors, yeah it works well but one bad batch off gas and then you need to pay $$$ to have the injectors cleaned and vapouriser(converter) cleaned,

But the liqiud injection is not a bad way to go as it runs like a normal petrol system just under higher pressure, any oil/garbage in the lpg gets burned up as there is no vapouriser(converter) for it to sit in, the Power limit to this system is much much higher than conventional systems, i have seen the system on a supercharged holden gen3 with no hickups

its seen on XR6 turbos with about 270 ish rwkw beeing the limit of both injectors and fuel pump, but Very soon they are releasing the high flow injectors and i believe some tanks with twin lpg pumps,

Me personally i have converted a few cars with this system and it does everything its supposed to verywell, the only down side is it doesnt have it own ecu like vapour so you "tune" it by flow matching the petrol injectors to the Lpg Injectors, wich works well if you have and adjustable computer of some description,

Cost wise it is a bit more than Vapour but maintaning the system is just a matter of filters and a leak test every 15000km and a Pump filter change, compared to the issue vapour has, Vapour is good but it will soon be Superseeded by liqiud injection

My 2 cents worth,

cheers

  • 1 year later...

I was looking into liqid LPG injection for my old BA 6.

Was strongly advised not to go ahead as there is currently no leglislation in WA for what mixture of propane/lpg (this was a while ago so im foggy on the specifics) is supplied. Propane has a much lower octane(i think :)), so liquid injection of LPG with a high propane content can lead to pinging/engine failure. The problem is magnified in a turbo car for obvious reasons.

Thats just what I was told by a gas fitter, feel free to correct me if im wrong.

Edited by SoFreshSoClean

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