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Hi-Octane Petrol Question

Discussion in 'Bling and Appearance' started by a-man, Mar 24, 2008.

  1. In Sydney there is currently a bit of a shortage on Hi-Octane petrol, and this has prompted a couple of questions.

    1. Can a bike that is supposed to run on 96 plus octane run ok on normal unleaded?

    2. If I can't find Hi-Octane and can only fill up with normal undleaded, would adding an octane booster help, or could it damage to my engine (I have a new GSXR 750)?

  2. 1; Yes, to a point. Just don't give it full throttle/high loads till you get decent fuel.
    2; Read bottle on octane booster, and ensure it providec the correct amount of "boost" you need.

    Regards, Andrew.
  3. It won't like it, and especially won't like big throttle openings at low
    revs. You'll know because of the nasty rattling sound.

    YES that's the perfect thing. Don't have to use too much, read the label as Andrew said, to get the correct amount.

    If all else fails, and you're lost in
    the outback with only crappy petrol, a capful of metho in the tankfull
    of crap petrol will give you a chance to get to the next petrol station.
    DEFINITELY not recommended for regular long-term use.
  4. Cam, just a question about the metho tip since it's a bit unclear. Does the metho boost the octane rating :? ...or by "Crap fuel" do you mean wet/dirty fuel?

    I packed some octane boosting additive for a long tour once, JUST INCASE I was stuck with std ULP. If you have to buy it at a servo, it'll be the most painful ~$20 you'll ever spend... so much better to pay BigW's / Repco's etc price... just a tip.
  5. Metho is HARDLY an octane booster...go do some research before spouting off BS.

    Regards, Andrew.
  6. Metho will help if theres a (tiny) amount of moisture in the fuel, as it will form a sort of emulsion with the water, and stop the engine spluttering as it gets large drops of water. Instead it will run normally with a small amount of water turned to steam. Acetone will do the same, but can damage some seals in pumps ect.
  7. Well that's my understanding too... but I was going to be nice first and let Cam clarify what he meant... :)
  8. Well, it's nice that you're prepared to be nice! I tried that for a while, and just got tossers picking apart everything I said, so thought I'd just join the club! :LOL:

    Regards, Andrew.
  9. Hi andrew, how are ya mate! Grumpy? Don't worry, we all get that way :grin:

    OK so here's my research (from wikipedia because it's easy).
    According to my calculations, that means that methylated spirits ('metho')
    has a RON (Research Octane Number) of 128.4.

    That's quite high. So if you have a 10 litre tank and you put in 400ml
    of methylated spirits, and top up with fuel at 91 octane (RON),
    the resulting mixture is 92.5 octane (RON). If your engine is designed
    for 93 RON, Hooray, you're done. If your engine is designed for 95 octane,
    you'll still probably get by, riding carefully. You could put in as much
    as 10% ethanol/methylated spirits, and that would get you to 94.7 octane,
    but I wouldn't recommend it.

    So yes, it's not the worlds' greatest octane booster, but it works.

    Would you like any more research? :LOL: :LOL:
  10. I'd dispute that, as my empirical findings in teh garage indicate that a hand soaked with methylated spirits will burn much cooler than one soaked in regular unleaded. :LOL:
    Octane number is not an indicator of a fuel's power output, it may have a high octane number, but remember, octane is a measure of a fuel's ability to resist knock or detonation. You will find that methylated spirits calorific value is WAY below unleaded petrol, and will cause a net loss in power output.
    Any hint of moisture in teh fuel wil kill that octane number right off too as methylated spirits readily combines with it and turns into glorified water..

    Regards, Andrew.
  11. That's a mighty big capful.

    Wow, that's about 2 cupfuls, and still not even 5% "alcohol".

    But a capful of metho added to a tank is still great for removing water from fuel...

    Cheers (sorry, I just couldn't resist :)

    Trevor G
  12. Ow :shock:

    I agree, haven't we always been talking about
    trying to get a gentle cruise to the next petrol
    station without detonation? Where did power increase
    come into the question? I know most ignoramuses (ignoramii?)
    say that high octane petrol gives them more power, but
    I agree that's not correct, and its not what we were talking about...

    I have not heard what water does to the RON of petrol. Have you got any
    reference for that? :LOL:
    All I know is that water in ethanol mix reduces the combustion
    temperature so that supercharged engines and rockets can
    run at temperatures which don't melt their insides.

    Yeah, to be honest I've always done about 2 cupfuls but I err on the
    conservative side when recommending to others (partly because I'm
    afraid they'll think "if 1 is good, 10 must be BETTER") :LOL:

    And we don't want people using it regularly or in large quantities
    because it's 10% methanol, and as Wikipedia says:

  13. I agree with what you've posted above, not going to quote it, it'll look messy!
    Yeah, most of the alcohols are corrosive in fuel systems not designed for it, particularlt methanol, which will also happily attack coper alloys (yep, most brass also has copper in it, as well as aluminium alloys) and some elastomers and rubbers. So, considering both modern EFI and old carburetted fuel systems use plenty of both, it's bad news.
    When I referred to fuel absorbing water, I was referring to teh alcohol as a fuel, although some petrol fuels will also absorb SOME small percentage of water.
    I once sumped a light aircraft, and had only ever heard about cloudy fuel, and this one morning, I finally saw it. The cloudiness was water in suspension. You think bikes are susceptible to condensation in fuel tanks? Most light aircraft use single skin tanks, and sit out in nice cold paddocks. They also have fairly primitive tank venting systems, which wil readily suck in large amounts of air when they cool.......I'll let you imagine the heat cycles.
    All I have to add to the alcohol fuel discussion is yes, as said, alcohol fuels are a much higher octane rating, but they take a lot more fuel by volume to create the same power, I think stoichiometric burn in alcohols is around 8-9 to 1 A/F ratio, where petrol is around 14.7? to 1. Those figures are from distant memory.
    So basically, you need a lot more per horsepower, and what I am saying is, sure, it'll raise octane, but it'll kill power. I've done that experiement too. Car farted and bucked under load with 2 litres methylated spirits to around 30 litres fuel.........

    Regards, Andrew.
  14. Spot on, sort of. Yes ethanol has a higher octane rating, but it also has about half the specific energy content. So a higher peak output is theoretically possible, but only if you can shove more fuel through the engine (ie much larger jets or injectors). This is why a lot of modern cars designed for E85 fuel are quoting significant increases in power output - but conveniently neglect to mention fuel economy.
    Of course the corrosive effects of ethanol on fuel system components is something that's been covered before (short answer - no Japanese motorcycle manufacturer recommends ethanol blends).
  15. Well, the USA has been using ethanol blends in a major way for years. It's HUGE! They are/were the biggest market for J bikes

    I don't remember seeing any warnings about using it over there.

    I don't recall reading of guys having corrosion issues in their motorcycle fuel systems in the US forums I frequent.

    Bio diesel is very highly concentrated as regards alcohol of some sort or other, and the dire predictions for people using it continue to be proven wrong. The most they have to do is run/change the fuel filter(s) initially as the rubbish passes through the system.

    Diesel injection, especially commmon-rail, is far more sophisticated, intricate, and susceptible to damage through impurities or bad "chemicals" than any sort of petrol system, and I just don't see the problem raised in car forums...

    I might just pop the question and report back...since we will be using more ethanol blends here shortly, also. I can't help thinking that those signs about "No Ethanol In Our Fuel!" have been disappearing around australian servos in the last few months, especially.


    Trevor G
  16. It's a conspiracy! Quick, call Pro-Pilot! :LOL:
  17. I've just done a google search and methanol as an octane booster is common enough... not the most favoured option, but still well noted.

    You learn something new every day.

    Thanks HotCam. :)
  18. The US doesn't get a choice on ethanol, even Hawaii is forced to add it to their fuel (which is laughable given how far the corn-derived ethanol has to be shipped). It's really only an issue with older bikes and/or those using a carburetted engine, I suspect the US just hopes no-one notices the negative affects (or at least can't prove them). There are definite disadvantages to high ethanol content fuels, ironically you only have to look as far as Mexico to see them - find it hard to believe these disappear completely at lower concentrations.

    As far as Aus. goes if I remember right the law was changed so that only fuels with more than 5% ethanol need to be labelled as a blend. So those that have removed the "ethanol free" signs are probably selling E5.

    As for biodiesel methanol is typically used in its manufacture but there shouldn't be any alcohols in the final product. The biodiesel itself consists of a mix of short chained esters which are a solvent and will corrode natural rubber components like gaskets and hoses in older diesels (ie pre 90s) - but they are very different to alcohols. Poorly made biodiesel is also hygroscopic and cold potentially cause severe engine problems. On the plus side the solvent properties of biodiesel means it's extremely good at clearing old gunk from the fuel system - unfortunately this usually ends up blocking the fuel filter (or worse yet the injectors).
  19. I always keep a bottle of metho in the fridge, for hot days.
  20. There are a number of bio-diesel users in the peugeot forum and these include folk with pre 90s cars and latest CR engines.

    None are owning up to any issues except the need to change filters regularly in the early stages as gunk is removed.

    I really think ethanol and bio-diesel fears are just that and not reality.


    Trevor G