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Car Forum / Land Rover Cars / May 2008Interesting!
Just been doing some maths. Assuming that V8's return an average of 14 mpg and diesels 28 mpg When Diesel costs £1.08 more a litre than pertol then we may all as well run V8's :-) in todays terms that meand petrol at say £1.08 a litre and Diesel at ....wait for it..... £9.82 per litre. :-( I feel better now having just put £98 of Derv in the Rangie! All calcs on a cost per mile purely on fuel alone.  Signaturewww.ULRC.net - Unofficial home of the unofficial www.lrproject.com - My tinkerings And my random piccys :- www.picasaweb.google.co.uk/fiveonadventure/ On May 21, 3:11 pm, "Lee_D" <newsgroupsNOS...@NOSPAMlrproject.com> wrote: > in todays terms that meand petrol at say £1.08 a litre and Diesel at > ....wait for it..... > £9.82 per litre. :-( £9.82 per gallon surely? >> in todays terms that meand petrol at say £1.08 a litre and Diesel at >> ....wait for it..... >> £9.82 per litre. :-( > > £9.82 per gallon surely? I donno there is certainly something ary with the maths... Lee had a V8 doing half the MPG than a diesel. So if diesel becomes twice the price of petrol, V8's become are cheaper to run even though they burn twice the quantity of fuel. At todays prices with petrol at 112p/l that would mean diesel at or over over 224p/l. SignatureCheers Dave. >>> in todays terms that meand petrol at say £1.08 a litre and Diesel at >>> ....wait for it..... [quoted text clipped - 10 lines] >At todays prices with petrol at 112p/l that would mean diesel at or over >over 224p/l. It's fecking well headed that way anyhow, but I reckon the petrol will more or less keep pace. SignatureAustin Shackles. www.ddol-las.net my opinions are just that Travel The Galaxy! Meet Fascinating Life Forms... ------------------------------------------------\ >> http://www.schlockmercenary.com/ << \ ...and Kill them. a webcartoon by Howard Tayler; I like it, maybe you will too! On Wed, 21 May 2008 08:47:20 -0700 (PDT), Colin Reed wrote: >> in todays terms that meand petrol at say £1.08 a litre and Diesel at >> ....wait for it..... >> £9.82 per litre. :-( > > £9.82 per gallon surely? I donno there is certainly something ary with the maths... Lee had a V8 doing half the MPG than a diesel. So if diesel becomes twice the price of petrol, V8's become are cheaper to run even though they burn twice the quantity of fuel. At todays prices with petrol at 112p/l that would mean diesel at or over over 224p/l. SignatureCheers Dave. Yep - though I used 1.09 a litre as my test for unleaded.... which means with your 112p/l that it would need to cost over £10 a gallon for v8's to be equal. I was initially still having my calculator set to "paying out" mode as opposed to "claiming expense mode" ;-) Lee D >>> in todays terms that meand petrol at say £1.08 a litre and Diesel at >>> ....wait for it..... [quoted text clipped - 14 lines] >Cheers >Dave. Convert the V8 to LPG and you're already there. - 57.9pplor less. Signaturehugh Reply to address is valid at the time of posting >> Lee had a V8 doing half the MPG than a diesel. > > Convert the V8 to LPG and you're already there. - 57.9pplor less. But you don't get the same MPG on LPG as you do on petrol do you? ISTR comments in here that it's noticeably lower. SignatureCheers Dave. >>> Lee had a V8 doing half the MPG than a diesel. >> >> Convert the V8 to LPG and you're already there. - 57.9pplor less. > >But you don't get the same MPG on LPG as you do on petrol do you? ISTR >comments in here that it's noticeably lower. Slightly lower - about 10% on a decent system Signaturehugh Reply to address is valid at the time of posting >> But you don't get the same MPG on LPG as you do on petrol do you? ISTR >> comments in here that it's noticeably lower. >> > Slightly lower - about 10% on a decent system Is that the best you can ever expect, or can you tune things any better ? Steve >>> But you don't get the same MPG on LPG as you do on petrol do you? ISTR >>> comments in here that it's noticeably lower. [quoted text clipped - 4 lines] > > Steve IME yes thats the best you will get. That was on our 3.9 v8 Multipoint injection system. :-( Lee D >>>> But you don't get the same MPG on LPG as you do on petrol do you? ISTR >>>> comments in here that it's noticeably lower. [quoted text clipped - 9 lines] > >:-( there's no need to be miserable about it. That's pretty good. As a rule of thumb, if you get less than 80% of the petrol economy, there's summat wrong with it, regardless of system. good modern system can get up to 90% as you noted. The reason is simple: Propane (and most autogas in this country is mostly propane) has less specific energy per litre then petrol. Diesel has more, hence why a modern diesel will out-economy a petrol engine, like-for-like. Nevertheless, with LPG typically about half the price of petrol, you can get something close to diesel fuel costs on LPG. Less so now, but traditionally, the V8s outperformed the diesels in the LR range by a good margin. And they sound better :-) SignatureAustin Shackles. www.ddol-las.net my opinions are just that Travel The Galaxy! Meet Fascinating Life Forms... ------------------------------------------------\ >> http://www.schlockmercenary.com/ << \ ...and Kill them. a webcartoon by Howard Tayler; I like it, maybe you will too! >there's no need to be miserable about it. That's pretty good. As a rule of >thumb, if you get less than 80% of the petrol economy, there's summat wrong >with it, regardless of system. Being one of those sad people who likes to keep very detailed records, I can say that over a period of time (4 years currently analysed) and taking into account various driving conditions, there is absolutely NO discernable difference in economy between petrol and LPG. If anything, LPG fairs a bit better when gently cruising on the motorway as it doesn't need lots of 'power'. Around town LPG fairs a tad worse - but on balance, no discernable difference. > Being one of those sad people who likes to keep very detailed records, > I can say that over a period of time (4 years currently analysed) and > taking into account various driving conditions, there is absolutely NO > discernable difference in economy between petrol and LPG. Good. That's something to aim for. Simon I. can get 18 mpg on his 101 AMBI, why can I only get 10.... Tinley tech ECU, power valve, lambda probe and TPS all fitted, time to wire them up.. Steve .mother>> Being one of those sad people who likes to keep very detailed records, >> I can say that over a period of time (4 years currently analysed) and >> taking into account various driving conditions, there is absolutely NO >> discernable difference in economy between petrol and LPG. IC engines are like any other heat engine they convert the chemical energy in the fuel into heat in a compressed gas and then extract work from it whilst that gas expands against a resistance. You cannot odds the fact that lpg has 70% of the calorific value of petrol. So if it returns the same mpg and there have been no modifications to the engine then there must be another reason. This could take many forms from slightly less acceleration to a cruising speed meeting with a sweet spot of the engine or being a bit weaker at tickover etc. >Good. That's something to aim for. Simon I. can get 18 mpg on his 101 >AMBI, why can I only get 10.... I can get 15mpg on lpg from the 110 at a motorway cruise and 19 on petrol. On a general about town runaround the lpg drops proportionally more, I put this down to poor mixture control with the gas chokes, it still costs less than 66% of running on petrol. The single most effective measure to get the lpg engine to be more thermally efficient is to up the compression ratio but to make the best of this would require higher gearing. In fact lpg is rather wasted on the 8.12:1 compression ratio I have. Still a lot better than my 2 1/4 petrol s3 which seldom bettered 14mpg with lousy performance to boot. I only used to get 8mpg with the 101, petrol, which is one reason I stopped using it as a workabout vehicle, I admit I didn't make any concessions to the low gearing and aimed to keep up with other traffic. Given the 101 slab front if you kept the cruising speed below 50mph and raised the gearing to give the same mph per 1000rpm I would expect to get similar figures as the 110 but people say that a 101 with tall gearing like that is sluggish, I cannot see why as they are much the same weight. AJH >IC engines are like any other heat engine they convert the chemical >energy in the fuel into heat in a compressed gas and then extract work [quoted text clipped - 4 lines] >from slightly less acceleration to a cruising speed meeting with a >sweet spot of the engine or being a bit weaker at tickover etc. I fully understand the physics and chemistry and can agree that should you take two identical engines powering, for example, a generator with constant measurable load you may find LPG provides less power. However, my hypothesis factors different driving conditions and attempts to demonstrate that there are certain factors which influence when LPG is more efficient. Now, should one be able to correctly predict these influences one could logically program a system to switch and pre-empt them in order to correctly fuel the engine. I would doubt, given the current technology when it comes to LPG conversions, that this would be feasible at present. My conclusion is based upon my measurements and demonstrates that over the 4 year period currently analysed, there is NO discernable difference overall. Notwithstanding, other conclusions are: A 4.6L V8 is more economical to run in _my_ 101 Ambi than a 3.5L V8 and A ZF 4 speed auto box has made it slightly less economical - but far better for my health and wellbeing, so I can live with that. >I only used to get 8mpg with the 101, petrol, which is one reason I >stopped using it as a workabout vehicle, I admit I didn't make any [quoted text clipped - 6 lines] >gearing like that is sluggish, I cannot see why as they are much the >same weight. I reckon my Ambi weighs somewhat more than a 110 <g> and have a lot of roof furniture that one would expect to cause more resistance. My calculations are currently showing an _overall_ average of 13.8mpg. This isn't as good as Simon gets, but Grumble does have a motorway 'sweetspot' of 68mph, which I try to maintain as whenever possible :-) > My > calculations are currently showing an _overall_ average of 13.8mpg. You don't suppose his maths is off a bit do you ? BTW Does that ACU on Grumble give you a performance hit ? Steve >> calculations are currently showing an _overall_ average of 13.8mpg. > >You don't suppose his maths is off a bit do you ? I haven't seen the data he's working from. He could be spot on, but I'd possibly question the telemetry. >BTW Does that ACU on Grumble give you a performance hit ? I fully expect it will do, when (cough) I eventually plumb it in... (I'm guessing at around a 7.5 to 19 percent hit, again, depending upon driving criteria and environmental factors. Quite a lot in real terms, but well within my 'comfort' boundaries). > I haven't seen the data he's working from. He could be spot on, but > I'd possibly question the telemetry. Has he got funny wheels or 'owt ? Still, its nice to have a target :-) >> BTW Does that ACU on Grumble give you a performance hit ? > > I fully expect it will do, when (cough) I eventually plumb it in... > (I'm guessing at around a 7.5 to 19 percent hit, Tis a biggie fer sure. Steve > Notwithstanding, other conclusions are: > > A 4.6L V8 is more economical to run in _my_ 101 Ambi than a 3.5L V8 > and > A ZF 4 speed auto box has made it slightly less economical - but far > better for my health and wellbeing, so I can live with that. The hope would be that the 4.6 had been developed a bit to give better performance, there must be 20 years of development between them. Given the 3.5 was 9,35:1 and the later 4.6 was 9.6:1 there should be an immediate improvement if pulling higher gears. Once the ZF has locked up does it still have more losses than a lt95? In fact what is the overall gearing difference between the two boxes, often autos will have higher gearing than equivalent manual boxes and the 4.6 should be pretty long leged in a range rover, the lt95 in a 101 had the lowest set of transfer gears fitted as well as the higher ratio diff gears. Does your lpg set up start as well as run on lpg? I always start and run on lpg unless I've got an empty tank so my figures are full to full with no petrol used between, if I start on petrol from hot I can travel about 1/3 mile on what;s in the carburettor bowls. <snip> >IC engines are like any other heat engine they convert the chemical >energy in the fuel into heat in a compressed gas and then extract work >from it whilst that gas expands against a resistance. You cannot odds >the fact that lpg has 70% of the calorific value of petrol. So if it >returns the same mpg and there have been no modifications to the >engine then there must be another reason. <Snip> Doesn't that argument assume that the engine is 100% efficient in each case and all the energy is released? Maybe with LPG being a gas is more efficient in using its inherent energy than petrol? I am no expert in this area so I may be totally wrong. Signaturehugh Reply to address is valid at the time of posting > <snip> > [quoted text clipped - 9 lines] > efficient in using its inherent energy than petrol? I am no expert in > this area so I may be totally wrong. Well it does assume that the combustion efficiency is the same in both case, I'll grant the lpg should burn out cleaner as evidenced by lower CO and HC emissions but I think this has only a minor effect on heat in the combustion. AJH >>there's no need to be miserable about it. That's pretty good. As a rule of >>thumb, if you get less than 80% of the petrol economy, there's summat wrong [quoted text clipped - 9 lines] >Around town LPG fairs a tad worse - but on balance, no discernable >difference. LPG also seem to suffer less when towing IME. Signaturehugh Reply to address is valid at the time of posting > But you don't get the same MPG on LPG as you do on petrol do you? ISTR > comments in here that it's noticeably lower. Yes, but its not HALF the economy! Steve > >> Lee had a V8 doing half the MPG than a diesel. > > > > Convert the V8 to LPG and you're already there. - 57.9pplor less. > > But you don't get the same MPG on LPG as you do on petrol do you? ISTR > comments in here that it's noticeably lower. On modern SGI systems it seems to be roughly 80-85% of the petrol economy. My 5.7V8 Chrysler does 26.5mpg on a long run on petrol, roughly 21-22mpg on LPG. At the price I pay for my LPG that is equivalent to 44mpg on diesel - the diesel version of my car only does 38mpg on a good day! I always compare LPG against diesel not petrol - let's face it, if you don't have a petrol engine on LPG you'd go for the diesel. My DII did 15mpg on LPG which at the time was equivalent (£ per mile) to 29mpg on diesel - I doubt if an auto TD5 would have returned 29mpg under anything other than extremely economical driving styles. Badger. > ... > My DII did 15mpg on LPG ... Where did you put the tank(s). SignatureWilliam Tasso Land Rover - 110 V8 Discovery - V8 >> ... >> My DII did 15mpg on LPG ... > >Where did you put the tank(s). Ours has the replacement dual fuel tank jobbie giving ~75l LPG and, erm, whatever space is left for petrol. D1 had cill tanks, but course the D2 has all the gubbins down there for ACE an the like, so no space for extra LPG tanks. On a long run the LPG-POI for the TomTom is handy :-) >>> ... >>> My DII did 15mpg on LPG ... [quoted text clipped - 3 lines] > Ours has the replacement dual fuel tank jobbie giving ~75l LPG and, > erm, whatever space is left for petrol. Ahh - didn't know there was such a thing. Ours is a D1 - this needs investigating. > D1 had cill tanks, but course > the D2 has all the gubbins down there for ACE an the like, so no space > for extra LPG tanks. It's a silly place on an off-road vehicle anyway. > On a long run the LPG-POI for the TomTom is handy :-) I bet. SignatureWilliam Tasso Land Rover - 110 V8 Discovery - V8 >> D1 had cill tanks, but course >> the D2 has all the gubbins down there for ACE an the like, so no space >> for extra LPG tanks. > >It's a silly place on an off-road vehicle anyway. You could always fill them with WD40 ;-) >>> D1 had cill tanks, but course >>> the D2 has all the gubbins down there for ACE an the like, so no space [quoted text clipped - 3 lines] > > You could always fill them with WD40 ;-) ha ha ha btw: found this http://www.rhel.co.uk/tomcattech/dizzy.htm SignatureWilliam Tasso Land Rover - 110 V8 Discovery - V8 >> You could always fill them with WD40 ;-) > >ha ha ha > >btw: found this http://www.rhel.co.uk/tomcattech/dizzy.htm Have you tried the rubber glove and pop-bottle solution? > Have you tried the rubber glove and pop-bottle solution? Well it's Friday night, you have to live a little! SignatureBlast off and strike the evil Bydo empire! http://youtube.com/user/tarcus69 http://www.flickr.com/photos/tarcus/sets/ On May 21, 3:11 pm, "Lee_D" <newsgroupsNOS...@NOSPAMlrproject.com> wrote: > in todays terms that meand petrol at say £1.08 a litre and Diesel at > ....wait for it..... > £9.82 per litre. :-( £9.82 per gallon surely? Yep! just testing! ;-) Lee D > Just been doing some maths. > [quoted text clipped - 11 lines] > > All calcs on a cost per mile purely on fuel alone. Well my V8 does 22mpg in my hybrid, so is that far better then a deisel? :-) Gary xx > Just been doing some maths. > [quoted text clipped - 7 lines] > ....wait for it..... > £9.82 per litre. :-( Won't be long...don't know how it is going over there, but over here, 2 weeks ago at the cheap supermarket garage it was 1,28€ / l, last week 1,35, this week 1,39. Most places are well into 1,40's now, if not 1,50. > 2 weeks ago at the cheap supermarket garage it was 1,28 / l, last week > 1,35, this week 1,39. Most places are well into 1,40's now, if not > 1,50. Blimely where is that Matt? Last week (14th) I paid 1.22, yesterday (24th) the same place was 127. I did see my first advertised 131 though. (Tesco J43 M6). All I bought was 25l of unleaded to pour into her indoors motor, cheaper than buying at the local place and as I was there and will last a while as she doesn't do a great mileage. The diesel/unlead gap had also got wider again to 13p/l. SignatureCheers Dave. >> 2 weeks ago at the cheap supermarket garage it was 1,28 / l, last week >> 1,35, this week 1,39. Most places are well into 1,40's now, if not [quoted text clipped - 7 lines] > > The diesel/unlead gap had also got wider again to 13p/l. I'm in France - Euro sign not so obvious, sorry! Euro rate currently around 1.22, so well above £1 / litre. With the euro rate as it is, I don't think we're too far different from the UK now in fuel costs. Bugger - no more gloating!! :( Still, at least diesel is cheaper than petrol here, by about 10c/l. Matt > > Just been doing some maths. > > [quoted text clipped - 11 lines] > weeks ago at the cheap supermarket garage it was 1,28€ / l, last week > 1,35, this week 1,39. Most places are well into 1,40's now, if not 1,50. Yes but you're talking euros, that's still not over a pound a litre. Martin >>> Just been doing some maths. >>> [quoted text clipped - 12 lines] > > Yes but you're talking euros, that's still not over a pound a litre. I bought some Euros last Wednesday via a French ATM & the rate was €1.06 to the pound, allowing for the bank charges. Shell diesel pump price in Le Touquet on Thursday was €1.46 per litre. About £1.37 per litre. Tciao for Now! John. |
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