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BP Ultimate Diesel?

Discussion in 'A3/S3/Sportback (8P Chassis)' started by cosmicblue, Dec 6, 2005.

  1. cosmicblue
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    cosmicblue Member

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    [Dec 6, 2005]
    One for the soot chuckers amongst us - I notice when buying the smelly stuff that BP (Esso too I think) offer an apparenty higher grade diesel fuel.

    Has anyone tried it? Does it make any difference? is it worth the extra 5p a litre?
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  3. OutLore
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    OutLore VOIP Dude

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    [Dec 6, 2005]
    yeah I tried it, does seem to add a few extra miles per tankfull, but not sure it's worth the extra £2.50 per tank as it probably doesn't give this back by the few extra mpg it offers.

    But it does contain cleaners etc apparently so I tend to use it once a month or so (about every 8-10tanks)
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  4. Karcsi
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    Karcsi Member

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    [Dec 6, 2005]
    What is the idea behind Ultimate Diesel? How is it supposed to give you more power? I can understand with higher octane petrol for cars with more powerful / advanced engines that can benefit from the lower combustability of the fuel. But with diesel?

    That's a point. How do you adjust the timing on a diesel? Is there any such thing? There is no spark plug to induce combustion, so it's the characteristics of the fuel that decides when it ignites? Surely then the grade of fuel can have an effect on the power of the engine?
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  5. auroan
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    auroan Active Member

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    [Dec 6, 2005]
    Igntion of th fuel in a diesel engine occurs at the auto-ignition point of the fuel. So with all the pressure in the cylinder (which creates heat - along with the glow plugs) the fuel ignites it's self. If you want to alter the timing, you alter the auto-ignition temp of the fuel / or the pressure in the cylinder.

    The burn characteristics of the BP ultimate fuel might be better than standard diesel, which is why BP may claim to give better performance ???
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  6. OutLore
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    OutLore VOIP Dude

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    [Dec 6, 2005]
    The equivalent of Octane in diesel is Cetane.... therefore I would think that a higher Cetane rating is the answer.

    BTW, I'm pretty sure that the glowplugs are only used when the engine is starting, not when it's running. Ignition in a diesel (Compression Ignition) is caused purely by the timing of the injection of the fuel into the cylinder... modern diesel engines are able to adjust the timing on the fly.....
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  7. Amchlolor
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    Amchlolor Active Member

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    [Dec 6, 2005]
    I alternate between it and 'normal' diesel all the time,purely depending on which garage is handiest.

    The only difference I notice with Ultimate diesel is that my car is a wee bit more reluctant to start from cold.

    It can take a few turns of the crank to fire up (like a petrol).

    Guaranteed as soon as I switch back to 'normal' diesel,it'll start as soon as the key is turned again.

    God knows why this is the case.

    Once the car is running,I'm beggared if I can tell any difference,sorry.
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  8. Karcsi
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    Karcsi Member

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    [Dec 6, 2005]
    Cheers Auroan. So the air is first compressed, creates a lot of heat, and the fuel can then be injected at varying points to adjust the timing as it will ignite on contact.

    Does a higher cetane value mean a more stable fuel, harder to ignite, like for petrol (which could be why Bowfer has problems starting the engine), but does not necessarily mean it contains a higher concentration of energy? But if you can already choose when ignition happens by adjusting the fuel injection timing, what difference does this make with a diesel engine?
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  9. auroan
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    auroan Active Member

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    [Dec 6, 2005]
    One of the things these chip boxes do (like a dragon box or a tunit) is alter the fuel injection timing to get more power for the engine by burning more fuel. Doing a bit more research, I think the the BP stuff is a combination of additives to clean your engine and increase cetane rating to improve the "burn" rate of the fuel;

    http://www.bp.com/sectiongenericarticle.do?categoryId=4005623&contentId=7009145
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  10. auroan
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    auroan Active Member

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    [Dec 6, 2005]
    [ QUOTE ]


    BTW, I'm pretty sure that the glowplugs are only used when the engine is starting,

    [/ QUOTE ]

    Yeah didn't word the post quite right. as you say the glow plugs are only used at the begining, as you need something to get the air hot to start with. Everything else is generated by the high compression ignition.
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  11. Amchlolor
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    Amchlolor Active Member

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    [Dec 7, 2005]
    [ QUOTE ]
    One of the things these chip boxes do (like a dragon box or a tunit) is alter the fuel injection timing to get more power for the engine by burning more fuel. Doing a bit more research, I think the the BP stuff is a combination of additives to clean your engine and increase cetane rating to improve the "burn" rate of the fuel;

    http://www.bp.com/sectiongenericarticle.do?categoryId=4005623&contentId=7009145

    [/ QUOTE ]

    I read an intersting comment from an engine tuner in a bike magazine last night.
    He stated that 'fancy fuels' are a waste of time unless you can get the fuel 'fresh'.
    Additives will,he says,evaporate in storage tanks and make them no better than normal unleaded.

    Of course,he was talking about petrol,but perhaps the same theory applies.
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  12. auroan
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    auroan Active Member

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    [Dec 7, 2005]
    Nah doesn't work like that for diesel, the flashpoint for diesel is 61C, so the storage tank would have to be at that temp or higher for it to start giving of vapours. It's true though for petrol, as the flashpoint is about -37C so it's easily giving of vapours in a standard ambinent temp storage tank.
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  13. Horchsense
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    Horchsense Member

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    [Dec 7, 2005]
    According to BP advertising boxxxxks - they kind of mess around with the molecular structure of the hydrocarbons somehow - buggered if I can tell the difference...
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  14. Karcsi
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    Karcsi Member

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    [Dec 8, 2005]
    [ QUOTE ]
    Nah doesn't work like that for diesel, the flashpoint for diesel is 61C, so the storage tank would have to be at that temp or higher for it to start giving of vapours. It's true though for petrol, as the flashpoint is about -37C so it's easily giving of vapours in a standard ambinent temp storage tank.

    [/ QUOTE ]

    So what vapours does diesel give off? It must do, otherwise why does it have a smell?
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  15. miketweed
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    miketweed Member

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    [Dec 8, 2005]
    At ambient temps diesel gives off vapours that smell, but not ones that burn!

    boil some diesel in a pan to then take a sniff - you'll tell the difference! :cool:

    Different elements evaporate off at different temperatures.
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  16. auroan
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    auroan Active Member

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    [Dec 8, 2005]
    [ QUOTE ]


    So what vapours does diesel give off? It must do, otherwise why does it have a smell?

    [/ QUOTE ]

    Just about everything gives of a smell, just because you can smell diesel doesn't mean it's evaporating quickly enough to drop all it's additives out of solution.
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