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Thread: 91 or 98 fuel?

  1. #16
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    Quote Originally Posted by steve_t View Post
    An engine will make the most power for the fuel it is tuned for. Engines with knock sensors can advance timing to get more power until they detect knock. If the engine can advance its timing sufficiently to take advantage of a higher octane's ability to prevent knock, this will yield the most power. Higher octane fuels usually have a higher energy content per litre
    Pretty much. It depends on what the vehicle is tuned for. Modern fuel injected motors compensate for different octane ratings and may or may not benefit from the higher. My C50T definitely seems to run better on 98 and in particular Gull's 98 blend so I use that whenever I can source it.

    Unless your bike is tuned for it, probably better to go with 91. Our Nissan Pulsar also seems to run better on 98, but it's hard to tell for sure without doing a dyno test.
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  2. #17
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    Quote Originally Posted by superman View Post
    My bike manual says 91+

    Would never put in 91 though, the extra kms I get from a full tank of 95 compared to 91 actually makes 95 cheaper per kilometre. (at least in my bike... and in my car too) and I "feel" more power, though if it's just my imagination it doesn't matter because 95 is still cheaper.

    Haven't tried a tank of 98 yet, because closest BP is about 30km away, Shell is only 10km away. So always just end up with 95. And that seems to work beautifully
    I agree. My bike goes about 9%-12% further on 95.

  3. #18
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    you can get 95 RON with less octane than 91 RON and the other way around.

    we use RON in NZ as a standard as it does not indicate how much energy is in each litre or how quickly it will burn or even how much octane is in it.

    Just how much compression it can handle without detonation compared to 100 percent octane, this is why you can get 120 RON fuel and you cannot have 1200ml of octane in 1L of fuel.

    Why? so you don't buy fuel that has a high amount of octane but additives which will cause detonation at lower pressures.

  4. #19
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    Quite a fair bit of info to take it. So should I stick with 91 or 98?

  5. #20
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    Quote Originally Posted by overworkedmonkey View Post
    Quite a fair bit of info to take it. So should I stick with 91 or 98?
    If it runs fine on 91 and doesn't detonate then use 91, unless higher octane fuels make it run better or give significantly better fuel economy.

  6. #21
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    Quote Originally Posted by Corse1 View Post
    I go with 91 in both bikes. I notice no difference with 98. Can't see the point of paying extra for no gain. As long as the engine does not emit any "pinking" noise then from all the posts I have read on different forums the lower octane is better.
    I run 91 in winter, and alternate 91 and 98 in summer, as the VFR pinks in hot weather, especially when the fuel level's low and the pump (which is in the tank) and the engine heat it up.
    I avoid running any brand of 95/96 in any vehicle, as there's too much toluene/xylene in it. It sooted up the plugs in my VFR750, and the wife's Peugeot pinks when running it, but is fine on 98, which is refined in Orstrylyer and is better fuel than our high octane crap.
    ... and that's what I think.

    Or summat.


    Or maybe not...

    Dunno really....


  7. #22
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    Quote Originally Posted by SMOKEU View Post
    If it runs fine on 91 and doesn't detonate then use 91, unless higher octane fuels make it run better or give significantly better fuel economy.
    When you say 'detonate' you mean? How would I know it doesn't 'detonate'? How would I measure a better run? Would that mean a greater distance? Also how do I know it isn't damaging the engine as such? Remember owning a BMW and was advised by the mechanics to use 98 as anything lower would damage the engine.

  8. #23
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    Quote Originally Posted by vifferman View Post
    I run 91 in winter, and alternate 91 and 98 in summer, as the VFR pinks in hot weather, especially when the fuel level's low and the pump (which is in the tank) and the engine heat it up.
    I avoid running any brand of 95/96 in any vehicle, as there's too much toluene/xylene in it. It sooted up the plugs in my VFR750, and the wife's Peugeot pinks when running it, but is fine on 98, which is refined in Orstrylyer and is better fuel than our high octane crap.
    Utterly lost and confused by the term 'pink'. What does it mean? How do I know it's occurring?

    When you say you avoid running any brand of 95/98? What does that mean? A particular provider e.g. Shell, Gull, BP, etc

  9. #24
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    Quote Originally Posted by overworkedmonkey View Post
    What would you recommend for a Honda CBR250RR? Tried doing a search but can't find anything specific. Whilst we are on the topic on fuel, what engine oil would you recommend? Any other suggestions would be welcome.
    I raced my CBR250RR's on 91 octane. They ran noticeably better on the lower octane gas. From idle right through to redline. Amazing little bikes. I've won races on Taupo, Manfeild, Philip Island, Broadford on CBR250RR's with 91 octane in them. It's cheaper and they got better gas mileage too. Mine were all Jap imports too.

    Pinking is onomatopoeia I believe for the noise that the engine makes when a cylinder's mix explodes before the spark plug fires and far enough before the piston reaches top dead centre that it tries to push it backwards for a little bit, thus you get a massive skyrocketing of pressure in the cylinder trying to push it backwards if only for an instant, I imagine it's quite stressful.

  10. #25
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    Quote Originally Posted by Juzz976 View Post
    you can get 95 RON with less octane than 91 RON and the other way around.

    we use RON in NZ as a standard as it does not indicate how much energy is in each litre or how quickly it will burn or even how much octane is in it.

    Just how much compression it can handle without detonation compared to 100 percent octane, this is why you can get 120 RON fuel and you cannot have 1200ml of octane in 1L of fuel.

    Why? so you don't buy fuel that has a high amount of octane but additives which will cause detonation at lower pressures.
    Completely lost me there. Considering I'm a complete noob to petrol, additives, compression, etc, can you explain what you mean followed by examples. Am trying to learn as much as I can.

  11. #26
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    Quote Originally Posted by vtec View Post
    I raced my CBR250RR's on 91 octane. They ran noticeably better on the lower octane gas. From idle right through to redline. Amazing little bikes. I've won races on Taupo, Manfeild, Philip Island, Broadford on CBR250RR's with 91 octane in them. It's cheaper and they got better gas mileage too. Mine were all Jap imports too.

    Pinking is onomatopoeia I believe for the noise that the engine makes when a cylinder's mix explodes before the spark plug fires and far enough before the piston reaches top dead centre that it tries to push it backwards for a little bit, thus you get a massive skyrocketing of pressure in the cylinder trying to push it backwards if only for an instant, I imagine it's quite stressful.
    Why do you refer to 91 octane specifically? Is there a difference between 91 and 91 octane? Sweet. Good to know that they are mean bikes to ride.

    So I presume the sounding being quite loud. When would I hear the noise? When you say cylinder's mix you mean? I know nothing about mechanics yet so forgive my ignorance. Keen to learn.

  12. #27
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    Quote Originally Posted by vtec View Post
    I raced my CBR250RR's on 91 octane. They ran noticeably better on the lower octane gas. From idle right through to redline. Amazing little bikes. I've won races on Taupo, Manfeild, Philip Island, Broadford on CBR250RR's with 91 octane in them. It's cheaper and they got better gas mileage too. Mine were all Jap imports too.

    Pinking is onomatopoeia I believe for the noise that the engine makes when a cylinder's mix explodes before the spark plug fires and far enough before the piston reaches top dead centre that it tries to push it backwards for a little bit, thus you get a massive skyrocketing of pressure in the cylinder trying to push it backwards if only for an instant, I imagine it's quite stressful.
    I haven't noticed any difference on my CBR if I run 91 or 98. It runs mint on 91, and it doesn't sound like it detonates on 91 so I just use that to save cash.

  13. #28
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    Quote Originally Posted by SMOKEU View Post
    I haven't noticed any difference on my CBR if I run 91 or 98. It runs mint on 91, and it doesn't sound like it detonates on 91 so I just use that to save cash.
    SMOKEU, would you mind explaining detonation or the sound of what a detonation sounds like? Maybe a Youtube video with the sound?

  14. #29
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    Put diesel.


    It's cheaper.


    If you can make it on Kiwibiker you can make it anywhere.

  15. #30
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    higher octane is more stable, so you can advance the spark further.

    the end.
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