I've noticed a reduction in economy of my bike over the last few weeks.
It could be the Valve clearances & carb balance.
However I suspect Low sulpher fuel may be to blame.
Anyone else found they get less mileage out of low sulphur fuel in highly tuned engines?
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Mileage from low sulphur fuel is worse. That's how Gordon Brown was able to reduce the duty by a couple of pence per litre in the budget, as he knew that consumption would go up and he would rake in more money.
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Thanks!
Care to put a figure on it?
Know any web sources that indicate why?Brian wrote:
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Off the top of my head the increase in fuel consumption quoted was around six percent. This was quoted in the papers a day or so after the budget, but I no longer have the article.
I haven't noticed much of an increase on my Honda 250U doing just under 80miles per day, two third on relatively open road and one third in London, but it does around 90 mpg (4 litres per day) so any increase would be negligible and masked by variations in traffic density.
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Brian wrote:
>
> Off the top of my head the increase in fuel consumption
> quoted was around six percent. This was quoted in the papers
> a day or so after the budget, but I no longer have the article.
No problem - if you read it in a paper that's good enough for me!
Many thanks.
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Every day I do 65 miles each way to work, mainly by motorway. The consumption of BP low 'sulphur' unleaded petrol of my 2.0 Mondeo is an average of 39mpg, which is the same as before the new fuel was introduced.
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What about low sulphur diesel? I have hears horror stories about it knackering diesel injection pumps. Anybody have any facts on this?
Mike Humpherson
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This was related to the reduced lubrication available from the fuel with reduced sulphur, which caused wear of injector pumps. I haven't heard much about it recently, so I assume this has been addressed in some way - probably an additive - but I'm sure someone will know the full answer.
The question I've got is why reduced sulphur in petrol should apparently have such a significant effect on fuel consumption. Sulphur content is very low and has no effect on calorific value, I don't believe it affects volatility, so is there any significant formulation difference between the fuels. References I have indiate petol can have a CV between 41.9 and 44.0 MJ/kg, a 5% variation. This would translate into a 5% difference in fuel consumption. Maybe these sort of differences are what is showing up here, although I can't inagine why the CV difference should be related to sulphur content. Are some fuel companies simply giving us less energy per gallon?
regards
John
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In order to remove the sulphur, the fuel goes through extra stages of processing. It is possible that this extra processing affects the fuel beyond just removing the sulphur, and this unintended modification could affect the performance of the fuel.
I heard that it was this extra processing which reduced the lubricity of diesel fuel, NOT the lack of sulphur. Anyone know more about this?
I have also heard that low sulphur diesel can cause shrinkage of rubber seals in diesel injection pumps, causing them to leak. I think this effect may be due to gradual leaching if small amounts of sulphur from the rubber?
Does anyone know if this problem has been solved, or which engines it applies to?
Mike Humpherson
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Loss of sulphur from rubber seals sounds a possibility with low sulphur fuels since I am sure that sulphur is added to natural rubber during the manufacturing process and lack of sulphur in the fuel would lead to an imbalance and leaching.
However, whether seals are natural or synthetic rubber I don't know, nor whether synthetic rubber contains sulphur. Any chemists out there?
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Mike is quite correct in saying its the extra processing which caused the problem in the early days of ULSD in Sweden. Pumps were knackered on a regular and then they started adding "lubricity enhancers." (Its in quotes because I don't know if that is English, probably Swenglish if its from Sweden)
Millers additives also improves the lubrication properties, and though its supposed to be in ULSD already it must help to have a bit more and certainly gets rid of smoke.
Re fuel consumption, I know that ULSD definitely has a lower density than good old smelly diesel, and maybe this explains the difference, if any, between normal and low sulphur fuel. Personally I could not notice any difference despite having to keep detailed records, (No I am not an anorak, its due to a severe case of bean counter/fleet manageritis)
Re seals: Only thing I know is that bio diesel definitely gives problems with the seals, unless the engine is specifiaclly set up for it. VW/Audi/Seat/Skoda are all definitely OK. Not heard anything re ULSD.
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Stuart
Thanks for confirming my thoughts about an additive solving the lubrication problem.
The density change is almost certainly the answer to the economy issue. We buy fuel by volume (litres), not mass (kg), and assess economy on a basis of miles achieved on a given volume of fuel. So, if the density reduces you get a lower mass per gallon. Assuming an unchanged calorific value (CV)
lower mass = lower energy content = fewer miles per gallon.
This effect accounts for much of the economy benefit from diesel. Diesel is 13.5% more dense than petrol, so you get 13.5% greater mass in your gallon or litre. (Don't tell Gordon Brown). As petrol and diesel have effectively the same CV, a gallon of diesel would give 13.5% more energy and thus also 13.5% more miles/gall than a petrol engine of the same efficiency.
They also have virtually identical carbon/ hydrogen ratios so you also get 13.5% more carbon dioxide from a gallon of diesel.
regards
john
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Stuart Bruce Wrote:
>adding "lubricity enhancers." (Its in quotes because I don't know if that is >English, probably Swenglish if its from Sweden)
I have seen the expression "Lubricity enhancers" used in English too, but I think a better alternative to the expression "Lubricity enhancers" is the good old fashioned word "Lubricant", but in this day and age, the trend seems to be to construct more complicated expressions to replace the traditional words we have grown up with.
Mike Humpherson
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Don't they use those in certain Swedish films? Shortened to "Lubes" I think.
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answer is in my opinion that uls fuel is pants as my car does far worse on it. But my freinds car shows no differnce. perhaps its engine specific if so it probably could be tuned out on a rolling road.
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