LPG versus Petrol. What's your view

[johnydep]

it's probably been done before, but it seems to be a passionate subject to most of us. So I created this thread to stop poluting another thread http://www.fordforums.com.au/showthr...7&page=2&pp=25

I have used LPG, I have a fitters licence and have had something to do with it for the past 15 years.
My feelings are mixed though, from what I have seen a well maintained LPG engine for the average user will last as long as a petrol engine, but most don't get the correct servicing & end up with oil leaks, mechanical noise & excess emissions.

A correctly maintained LPG engine should have the same or better life span than its petrol counterpart, but that's rarely the case & the manufacturers know it.

The reasons;
LPG produces more acids than petrol, the oil breaks down quicker but looks clean, the acids attack bearings & seals. Check out the recomendations from the manufacturers, you'll see that LPG engines require a higher rating.
LPG also causes oil to thicken with age, so not changing oil & filter at specified intervals leaves a too thick oil to circulate to the valve train.
Petrol has a natural cooling effect, this causes the air/fuel charge to be denser (more power) and also helps cool the valve & top piston ring. LPG does not have this, so there is more heat stress in the combustion chamber.

So there is good and bad with LPG.

http://www.wps.com/LPG/WVU-review.html

Performance and drivebility of propane vehicles is essentially the same as for gasoline vehicles. For propane, the gas displacement effect is 4%, it means that the displacement of air by propane causes reduction in power of 4 % (volumetric efficiency decrease) from an equilevent gasoline counterpart. Gasoline on the other hand, provides evaporotive cooling of the intake air which increases the intake air density and increases the power. Test results show 6 % less power with propane than with gasoline[11]. Propane has a research octane rating of 110 to 120, thus, it resists engine knock better than gasoline (gasoline 87-94 ) allowing a higher compression ratio for the engine, see Figure 1. Propane contains about 5 % more energy per unit mass however the density is nearly 32 % less. The net result is that a litre propane contains 28 % less energy than a litre of gasoline, Table 4. Assuming that an engine is operated on propane and gasoline with equal efficiency, more litres of propane will be consumed to provide equilevent performance. Fortunately, engines generally operate on propane with greater efficiency than on gasoline so that the increase in fuel volume is not as great as the energy comparison suggests. Propane fueled vehicles can achieve the same driving range as a gasoline vehicle by installing a slightly larger tank. Propane use consumes approximately 5 % more fuel for equivelent performance but it costs 15 % less than gasoline.

Question; Two identical engines, one with slightly less power, which one will wear out first if driven in identical ways?

[Steffo]

As I've stated many times, LPG all the way. It's a hell of alot cheaper then petrol (118.9 cpl regular, 127.9cpl premium, 38.9cpl LPG), and IMO, a much better fuel.

[chevypower]

i know LPG isnt 100% propane , i think its got a mix of Butane? But it's a lot more than 5% more in consumption, burns hotter, smells aweful, isnt much cheaper than petrol when you remove the big tax component from both and take in to consideration its 25% increase in consumption, non lubricating for the engine, and despite all the theories in the world, less power is usually achieved in reality. So i cant see a lot of advantage to it, other than its taxed a lot less at the moment

[Steffo]

I'll also post this up from that other thread.

[EFFalcon]

lol @ when you remove the big tax component, when is that going to happen.
given excise on LPG will still have LPG costing around 1/2 what ULP does..
and when u consider its currently almost 1/3 the cost of ULP.. LPG rocks.

[Steffo]

Originally Posted by chevypower

i know LPG isnt 100% propane , i think its got a mix of Butane? But it's a lot more than 5% more in consumption, burns hotter, smells aweful, isnt much cheaper than petrol when you remove the big tax component from both and take in to consideration its 25% increase in consumption, non lubricating for the engine, and despite all the theories in the world, less power is usually achieved in reality. So i cant see a lot of advantage to it, other than its taxed a lot less at the moment

25% increase? Are you seriously kidding? 25% increase = absolutely horrible, shockingly tuned setup. On average, you should burn approx 1.2 litres of LPG per 1 litre of petrol. That's ALOT less then 25%.

And petrol fumes are alot worse to smell then LPG fumes... petrol fumes give me a headache... LPG fumes just stink like rotten egg, but no associated issues from smelling them. They're far less toxic.

[Pilch]

Cost effectiveness of LPG is the number 1 argument for LPG, not matter which way you look at it. $0.50 vs $1.30 is an amazing difference, and even with the so called 28% difference as stated above, it's still a cost effective fuel compared to petrol!

I think the biggest problem with LPG that gives it a bad name is people run dual fuel and leave their engine setup for petrol.... obviously you litres consumption for every 100km's and power output will be better on petrol in this situation. If instead you change your setup for LPG, economy and performance figures will tell a very different story.

The other point I'd like to make is LPG will be around for the same length of time as Petrol, and is likely to always be cheaper! Plus LPG produces less emmisions and is therefore given exemptions to restrictions on certain laws to govern emmisions released into the environment.

The point above about oil and LPG causing it to go acidic is a crucial point, and some oils don't even tolerate this well and will breakdown VERY quickly. regular maintenance with special attention to oil and ignition system is crucial to a good LPG powered vehicle.

I don't think I could ever drive a petrol powered car, simply on the basis of cost!

that's my 2c

I use LPG...... on LPG 20 bucks for 2 days..... on petrol 60 bucks for 2 days

[Steffo]

Originally Posted by Pilch

The point above about oil and LPG causing it to go acidic is a crucial point, and some oils don't even tolerate this well and will breakdown VERY quickly. regular maintenance with special attention to oil and ignition system is crucial to a good LPG powered vehicle.

I don't think I could ever drive a petrol powered car, simply on the basis of cost!

that's my 2c

Thing is.. you're supposed to run different oil with LPG anyway..

http://www.caltex.com.au/products_oil_detail.asp?id=316

Plus don't forget the higher octane rating for LPG, making it able to utilise higher compression and higher boost without knock. That's a great thing in a performance orientated engine.

I'm still of the opinion that LPG is going to become the next big thing in Australia, until we all move to hydrogen fuel cell cars...

[Casper]

Originally Posted by Steffo

25% increase? Are you seriously kidding? 25% increase = absolutely horrible, shockingly tuned setup. On average, you should burn approx 1.2 litres of LPG per 1 litre of petrol. That's ALOT less then 25%.

Sure is, its only about 20% :

[Steffo]

Originally Posted by Casper

Sure is, its only about 20% :

See... I failed maths at school :

[Sourbastard]

Originally Posted by Steffo

until we all move to hydrogen fuel cell cars...

is that the same week we all move into gumdrop houses on lolly pop lane?

[EFFalcon]

how many people out there are running aftermarket ECU's and thus are getting perfect AFR's on Petrol? not many, therefore they're getting $hitful AFR's and the theoretical 'difference' doens't apply.
LPG consumption is closer then 20% due to the AFR's being far closer then that of a factory ULP car.
sure, if you have an aftermarket ECU then your petrol consumption will be better, but your LPG performance will be better too (ignition curves)

[RED_EL_XR8]

Originally Posted by Steffo

As I've stated many times, LPG all the way. It's a hell of alot cheaper then petrol (118.9 cpl regular, 127.9cpl premium, 38.9cpl LPG), and IMO, a much better fuel.

And to back this up you run your own vehicle on?

[Steffo]

Originally Posted by RED_EL_XR8

And to back this up you run your own vehicle on?

PULP, as required per owner's manual, until I can afford the LPG swap. Don't worry, it'll be on gas sooner or later :P

[Gammaboy]

Originally Posted by RED_EL_XR8

And to back this up you run your own vehicle on?

Grade A milk and chocolate chip cookies!

[Sourbastard]

Originally Posted by Gammaboy

Grade A milk and chocolate chip cookies!

The only car in Australia on a low GI diet.

[GraveDilute]

Both of my cars are LPG, one dedicated and one duel fuel.
Yes, LPG requires a bit more care, but the price difference on a weekly basis ($26 versus $78 per tank of gas) more than makes up for the cost of higher grade oil when changing, or higher spec spark plugs, etc.
LPG is a non-imported product, is less polluting than petrol, and allows me to spend more money on goods and services which benefit the domestic economy.

If you've never run a car on gas, then you're not qualified to comment.

[MITCHAY]

I only spend about $30 a week so it isnt too expensive. Of course i wouldnt mind the price to come down but at the moment it isnt a turning point to go to LPG.

[RED_EL_XR8]

Originally Posted by GraveDilute

Both of my cars are LPG, one dedicated and one duel fuel.
Yes, LPG requires a bit more care, but the price difference on a weekly basis ($26 versus $78 per tank of gas) more than makes up for the cost of higher grade oil when changing, or higher spec spark plugs, etc.
LPG is a non-imported product, is less polluting than petrol, and allows me to spend more money on goods and services which benefit the domestic economy.

If you've never run a car on gas, then you're not qualified to comment.

Of course these two vehicles you have are identical other than the previously mentioned duel fuel conversion and both used in an identical manner, and service completely by the same accredited organisations aren't they to back up your scientific claims.

[Pilch]

Originally Posted by Steffo

Thing is.. you're supposed to run different oil with LPG anyway..

http://www.caltex.com.au/products_oil_detail.asp?id=316

Plus don't forget the higher octane rating for LPG, making it able to utilise higher compression and higher boost without knock. That's a great thing in a performance orientated engine.

I'm still of the opinion that LPG is going to become the next big thing in Australia, until we all move to hydrogen fuel cell cars...

Actually you don't have to run different oils, some oils are practical on both. It depends on the qualities each oil has, but yes, some oils are just completely impractical for LPG.

I stated that changing your setup to suit LPG is necessary to achieve realistically comparable performance and economy figures, if I was to elaborate I would say what you said.... plus a recurved dizzy or aftermarket ECU.

The only thing I don't agree on is LPG becoming big in Australia. It won't happen because so many people believe the myths that surround the fuel.

Originally Posted by MITCHAY

I only spend about $30 a week so it isnt too expensive.

And with that $30 you travel how many km's? And your car produces how much power?

A petrol powered car simply can't compete with a well setup LPG car with todays prices!!! :voldar02:

[niko]

as a student on virtually no income gas is the answer for me

[GraveDilute]

RED EL, I don't understand what you're trying to criticise.
My so-called "scientific claims" are baed on primary school mathematics:
65l x $1.20 = $78
65l x $0.40 = $26
I'm not pulling crap out about reduced air flow, blah, blah.
Yes, the car does use gas more than petrol, I'm not disputing that. But at 1/3 the cost of petrol...even a primary school kid can see the difference

[RED_EL_XR8]

Originally Posted by GraveDilute

RED EL, I don't understand what you're trying to criticise.
My so-called "scientific claims" are baed on primary school mathematics:
65l x $1.20 = $78
65l x $0.40 = $26
I'm not pulling crap out about reduced air flow, blah, blah.
Yes, the car does use gas more than petrol, I'm not disputing that. But at 1/3 the cost of petrol...even a primary school kid can see the difference

Yeah and BA XR8 holds 60L so does my Mums Camry? Are the usages of the 2 vehicles you mentioned identical a one third fuel price may sound attractive but it wont have the same impact on TCO of the vehicles, in fact in many applications the gas vehicle will end up the more expensive option.

Most fleet managers have done a lot more sums than the high school math you quote.

[MITCHAY]

Originally Posted by Pilch

And with that $30 you travel how many km's? And your car produces how much power?

I travel about 300-400kms mostly peak hour traffic and when I am moving i flog the s**t of it. Lol and it produces a whopping 87kws but yet is still enough (I dont need a V8 supercar). Ive gone a week on $15 before but thats just too boring. I dont always put the same amount in every week. Sometimes ill put in $20 or $25 but mostly $30.

[johnydep]

One thing I forgot to mention, and everyone else seem oblivious to is;
LPG puts extra stress on the cooling system & auto transmissions.
Most auto's use coolers inside the radiator tank, so higher cooling system stress cause higher transmission stress, on top of this the engine produces less power, so more throttle is required which increases transmission stress & heat which is dumped into the radiator cooler, and round it goes again.

And what about that exhaust temperature, what is that doing to catalytic converters & oxygen sensors?

[GraveDilute]

Originally Posted by RED_EL_XR8

Yeah and BA XR8 holds 60L so does my Mums Camry? Are the usages of the 2 vehicles you mentioned identical a one third fuel price may sound attractive but it wont have the same impact on TCO of the vehicles, in fact in many applications the gas vehicle will end up the more expensive option.

Most fleet managers have done a lot more sums than the high school math you quote.

OK, I believe you are coming from a different set of assumptions than I am, hence the confusion.
If you are arguing against the conversion of an existing car to LPG, there are a number of valid points against doing so. No of cylinders of car, no of kms driven and in what conditions, etc, etc.

If in my case, I had the choice between spending money on a car only on petrol, and on the same model car with LPG. It was a no brainer. LPG wins hands down.

Do I drive my duel fuel car on petrol because of theoretical efficiency advantages and x kw difference at the wheel? NO

[Black XR6]

Ok, will those on the con side of this debate actually start posting some hard information that has actually been researched beyond heresay and questionable personal experience?

I had performed about an hour or so searching on google to try and find articles on lpg and could not find one credable site that proclaimed LPG was bad for your engine or pocket. Plenty though said the opposite.

[GraveDilute]

Originally Posted by Black XR6

Ok, will those on the con side of this debate actually start posting some hard information that has actually been researched beyond heresay and questionable personal experience?

I had performed about an hour or so searching on google to try and find articles on lpg and could not find one credable site that proclaimed LPG was bad for your engine or pocket. Plenty though said the opposite.

HEAR HEAR

[RED_EL_XR8]

Originally Posted by Black XR6

Ok, will those on the con side of this debate actually start posting some hard information that has actually been researched beyond heresay and questionable personal experience?

I had performed about an hour or so searching on google to try and find articles on lpg and could not find one credable site that proclaimed LPG was bad for your engine or pocket. Plenty though said the opposite.

google search on "lpg pitfalls"

LPG is fine in engines optimised to run LPG though the economy arguements still hold true. Duel fuel and its budget & backyard conversions on petrolium engines, I'll leave that to those more desperate....