LPG Discussion Forum

You definitely do lose out - you can't get more or the same mpg out of a fuel which is 80% as effective.

I've been bleating on about this for ages.

Exactly why diesel is cheaper pence per mile.

clanless wrote:You definitely do lose out - you can't get more or the same mpg out of a fuel which is 80% as effective.

Pulease - it's not 80% less effective, it's actually got a higher calorific value and octane rating than petrol when measured by mass. It's only worse in MPG because we (somewhat perversely) insist on measuring (and taxing) fuels with vastly different densities by volume.

There is 40% more mass in a litre of petrol than there is in a litre of (liquid) propane - that, and that alone, is the reason consumption is higher in 'mpg' terms than petrol. There isn't a 40% difference because of the higher calorific value which significantly offsets the loss.

And the difference for diesel isn't all down to the fuel. A lot is down to the higher compression ratio which gives significant thermodynamic efficiency gains due to the higher combustion temperature.

And the same issues apply when you consider alternative like methanol and ethanol which have different properties again - I believe Methanol has a 30% disadvantage tax wise due to the taxation by volume irrespective of energy density.

I don't want to get into another detailed debate about it - you get more mpg from petrol - lpg is therefore not as effective as a road fuel.

clanless wrote:I don't want to get into another detailed debate about it - you get more mpg from petrol - lpg is therefore not as effective as a road fuel.

Ever thought about starting a diesel lovers forum and just going on and on about your constant drivel in there because no one really gives a monkies about your opinion in here.

How rude.

Good manners cost nothing.

If you really can't be civil, then don't post on the forum.

I think you should be banned.

I've prooved that an LPG car can achieve the same mpg as a petrol car ..
but it involves the car being a lot slower in acceleration and loosing top end .

that i was able to do with open loop on my sierra

38 mpg on a run was regular ..even a bad run with a few traffic jams got me 35....and this is out out of an eight valve single cam car

I've found that ambient air going into the air intake improves the situation more ...i found that the car was at it most efficient mpg wise when ambient air going into the air intake was plus 20 degrees centigrade..

don't think to yourselves, that the hot air intake around the manifold improves things... it didn't ....because it was restrictive ...and made the open loop pull more gas in to the engine.

Since the installation of this sequential system ...days above 20 degree c have been rare ...and Ive not been able to see if it happens ..

i had more scope with the sierra ...i could mess around with it a lot more ..for instance ..i had the ignition moved by 6 degrees..via the octane adjust plugs .

this car i have now (420 ROVER) leves you no scope, as every adjustment will be over ruled by the lambda signal and air sensor


so if you want the best economy ...buy an old car with no lambda.

some people said you must be running week .......it wasnt... it just accelerated slower ....what with the restriction of the mixer ...made it a boring car to drive ...but looking back ...i now miss the hell out off the good mpg it got.

all the best.markj

clanless wrote:How rude.

Good manners cost nothing.

If you really can't be civil, then don't post on the forum.

I think you should be banned.

I will politely point out that you come across as being arrogant and a bit of a troll - just stating how you come across. You seem closed to the fact that others might not share your opinion.

Your opinion, which you state as fact, that LPG is less effective as a fuel than petrol is based on a narrow definition off effective where your ONLY measure is an arbitrary choice of distance/volume. There are other measures - cost, emissions, what it does to the engine, available power, etc. I consider cost/mile to be a significant measure of 'effective' - for me that makes LPG far better than petrol, even at todays prices.

It may be of interest to you that LPG is starting to become common in motorsport simply because it is MORE effective as a fuel - it's higher calorific value and octane rating allow engines to be 'turned up' more and give more power for a given capacity whilst still running on pump fuel. An alternative (where allowed by event rules) is to spend a LOT of money on what some of us call 'funny fuel', some synthetic blend that costs about five times as much as petrol. Clearly, for those using it, it is MORE effective by their measure - even if that measure isn't the one you might choose.

Could I suggest therefore, that you consider that yours might not be the only valid opinion and treat others with a bit of respect ? We might all get along better that way. the_mothman might not have expressed it too elegantly (something I'm guilty of at times), but the jist of what he says is not far off - if LPG is so bad, then why are you hanging around in a forum which is expressly for discussion of LPG ?

clanless wrote:How rude.

Good manners cost nothing.

If you really can't be civil, then don't post on the forum.

I think you should be banned.

I will politely point out that you come across as being arrogant and a bit of a troll - just stating how you come across. You seem closed to the fact that others might not share your opinion.

Your opinion, which you state as fact, that LPG is less effective as a fuel than petrol is based on a narrow definition off effective where your ONLY measure is an arbitrary choice of distance/volume. There are other measures - cost, emissions, what it does to the engine, available power, etc. I consider cost/mile to be a significant measure of 'effective' - for me that makes LPG far better than petrol, even at todays prices.

It may be of interest to you that LPG is starting to become common in motorsport simply because it is MORE effective as a fuel - it's higher calorific value and octane rating allow engines to be 'turned up' more and give more power for a given capacity whilst still running on pump fuel. An alternative (where allowed by event rules) is to spend a LOT of money on what some of us call 'funny fuel', some synthetic blend that costs about five times as much as petrol. Clearly, for those using it, it is MORE effective by their measure - even if that measure isn't the one you might choose.

Could I suggest therefore, that you consider that yours might not be the only valid opinion and treat others with a bit of respect ? We might all get along better that way. the_mothman might not have expressed it too elegantly (something I'm guilty of at times), but the jist of what he says is not far off - if LPG is so bad, then why are you hanging around in a forum which is expressly for discussion of LPG ?

May I commend those that get off their bum and write to Brown ( aka the tax maker ). During my brief flirtation ( 18 months ) with LPG, I too wrote re his decision to start reducing the excise duty differential between pet and LPG, pointing out that people had spent thousands on conversions and were interested not only in the money saving aspect when using LPG but the environment as well.

The waffling response when you read between the lines was similar to that bank ad on the telly, the one were they hoike people in with a low interest rate then increase it.

SimonHobson wrote:

clanless wrote:How rude.

Good manners cost nothing.

If you really can't be civil, then don't post on the forum.

I think you should be banned.

I will politely point out that you come across as being arrogant and a bit of a troll - just stating how you come across. You seem closed to the fact that others might not share your opinion.

Your opinion, which you state as fact, that LPG is less effective as a fuel than petrol is based on a narrow definition off effective where your ONLY measure is an arbitrary choice of distance/volume. There are other measures - cost, emissions, what it does to the engine, available power, etc. I consider cost/mile to be a significant measure of 'effective' - for me that makes LPG far better than petrol, even at todays prices.

It may be of interest to you that LPG is starting to become common in motorsport simply because it is MORE effective as a fuel - it's higher calorific value and octane rating allow engines to be 'turned up' more and give more power for a given capacity whilst still running on pump fuel. An alternative (where allowed by event rules) is to spend a LOT of money on what some of us call 'funny fuel', some synthetic blend that costs about five times as much as petrol. Clearly, for those using it, it is MORE effective by their measure - even if that measure isn't the one you might choose.

Could I suggest therefore, that you consider that yours might not be the only valid opinion and treat others with a bit of respect ? We might all get along better that way. the_mothman might not have expressed it too elegantly (something I'm guilty of at times), but the jist of what he says is not far off - if LPG is so bad, then why are you hanging around in a forum which is expressly for discussion of LPG ?

Yeah what he said
To be honest I'm not too fussed about clanless' opinion of me or whether or not he thinks I should be banned for using the word 'monkies'

I think you Simon have hit the nail on the head that clanless' does come across as arrogant and a troll and that all of his posts are the same. This at the end of the day is a forum for people who use, like and appreciate the benefits (financially and more importantly environmentally) of LPG.

Diesel at this present time 'may' offer a better price per mile than even LPG but it will never compare to LPG for its environmental benefits. Therefore, may I politely request that unless clanless has something different and more constructive to post... then simply... don't!

Meanwhile, back on topic....

Don't worry Clanless my father-in-law would like you he's always going on about his blessed diesel Espace!

The fuel debate will go on and on because there is no definitive answer.

Over the summer I made a car run on neat Hydrogen on behalf of the local University. This has only water vapour coming out of the tail pipe so beat that with the LPG v Diesel v Petrol emissions argument. But even that's not the answer fully. How do we get the hydrogen? How do we store enough inside a car, the tank cost £3000! and holds much less in miles than an equivalent petrol or LPG tank would because it's held as a gas not a liquid.

In September I attended the alternative fuel conference and we exhibited the car conveted to hydrogen. There was talk of cars running on water and wind and electricity and stuff about biofuels and so on and so on. Generally I came away and thought we should probably all buy pedal bikes!
Not only would the emissions be less but we would save £35 a month on gym membership too!

The problem with the diesel/lpg/petrol debate is that they are all the same thing really just hydrocarbons. Take the carbon away and they are difficult to store add the carbon and you get carbon emissions, naturally.

To defend the government for a minute, if I dare, diesel was seen as the super fuel back in the 70s and 80s when petrol cars were dirty and fuel was leaded. Petrol cars cleaned up there act and tax on diesel was increased. In the 90s LPG was the panacea as it produced much less CO. (No one really cared about CO2 then). Cars then all became injected with CATS,OBDII ,multi lambda probes etc and now LPG is better than petrol emission/km wise but much less so than it was in the past and only if the system is well set up. Consequently it seems fare to adjust the relative tax on LPG to petrol accordingly and to reflect that LPG has lost some of the emissions advantage that it had in previous years.

Cost per litre from a global perspective is irrelavant because it's artificial. If it were decided that a certain fuel was dirty then double the tax on it and no one would use it.

The problem for LPG is the retro fit nature of it the systems. Some are very well installed others....well you may aswell attack your car with an industrial power drill whilst blindfolded. Consequently some lpg conversions give out low emissions and some dont. Unfortunately, that's not the end of the story. On some cars, no matter which make of equipment and how surgically carefully the system has been painstaking crafted onto the car, the bloody thing still stalls or missfires slightly or losses power or all three!

The only way, in my humble oppinion (others may differ, please don't call me a troll ) for the lpg industry to survive and prosper fully is for the car manufacturers to include the system on their cars from new but after extensive testing and giving good gaurantees. Not grab the cheapest pile of poo you can get so as to grab the headlines and jump on the band waggon then leave all quality issues to your dealer network who in the main dont want to know Mr Vauxhall!

Well, glad that's off my chest, going for a coffee!

"MORE effective as a fuel - it's higher calorific value and octane rating"

I understand the LPG has a higher Octane rating but doesn't it have a lower calorific value than petrol?

Not on an equivalent density by volume basis.

we are talking miles per gallon here ...that's ...what most of the topic is about ..


so if we are talking miles per gallon ..lpg has less calories per gallon as in a gallon you pay for ...compaired with a gallon of petrol you pay for .

all the best.markj

Mothman - you don't know me and I don't know you. I very much doubt that if we actually met in real life that we would get on.

Fortunately, I can simply avoid forums and people like you - which I intend to do.

Quite frankly I don't really care whether you take my views on board or not - as far as I am concerned you are just 'someone' posting onto a website.

You no doubt will reply to this with some sarcastic comments - hey knock yourself out. I won't be reading it.

Have also sent a slightly revised version to Cameron and Clegg for their views.

Active_Lad wrote:Have also sent a slightly revised version to Cameron and Clegg for their views.

Nice work. I wonder how long it takes to get replies in?
Still no reply from my MP whom I emailed about this the other week.

the_mothman wrote:Still no reply from my MP whom I emailed about this the other week.

To be honest, it's simply not worth writing to my MP.

Firstly, he (or his assistant) doesn't even reply to most of my letters now - not that I write that often.

Secondly, he's a minister with a track record of voting with Government policy. So unless what I want him to do happens to coincide with Crash Gordon's wishes then nothing is going to happen anyway. Lets just say that my views don't have much in common with Crash's

Reading the local rag, it's clear that I'm not alone. Trouble is, knowing the way the main town in the constituency works, I can see him getting in again next time around - there's nowt as queer as folk, as the saying goes.

And since Watchdog had a piece of variable petrol prices tonight, I've eMailed them asking why they didn't cover LPG