Octane ratings explained

Discussion in 'Technical' started by brian66, Sep 11, 2009.

  1. brian66

    brian66 Ol'Timer

    I would like to add my 10 cents worth of information to the fuel subject and hopefully give some useful information.
    The octane rating of a fuel is related to its ability to ignite.
    Higher octane ratings will result in a resistance to ignite. This is to prevent “Knockingâ€
  2. Loading...

  3. monsterman

    monsterman Ol'Timer

    Although my Ducati runs well on Gasohol95 I often stop at Shell and fill with VPower non gasohol 95 as it will help keep the system clean from nasty deposits gumming up the injectors etc ......the downside is the cost it is 25% more than gasohol.Today Vpower was 41.2 baht alitre and gasohol 95 31.2 baht a litre.
  4. brian66

    brian66 Ol'Timer

    Yes, i forgot to mention the disadvantage of the price.
    I presently have 5 high performance bikes in my home workshop and i dont want them stuffed up with that gunk from the bio fuels so i buy Shell and i dont even consider the price.
    Because pure fuel bowsers are limited. I stock up with fuel containers when ever i pass a Shell in my ute and keep the fuel in a cool place in my workshop.
    I will only use the pure fuel in my new CBR1000RR and R1. That is until the people in power make the pure fuel unavailable any more.
    Price will rule in Thailand so i expect the pure fuel to dissappear in the coming years.
    I work away from Thailand so my bikes are not running regularly.
    I have a couple of new 450 dirt bikes and they will not start if i leave the bike sit for a couple of weeks. Bio fuel clogs the system. I am using Shell in those bikes now.
    if you have an 1198 or similar Ducati i would be using pure fuel. If you have to use Bio fuel and the bike is ever stored, you should drain the fuel system and flush it with Alcohol.
    You will not notice any performance difference using pure fuel, Bio fuel, 91 or 95 Octane fuel in a new engine. But using pure fuel is a cleaner and more trouble free option for your engine in the long term.

    But given time, Bio fuel is going to foul up the fuel system compared to pure fuel regardless of your efforts.
    Leaded fuels will do the same but it takes some thing like 5 years of storage to clog up but leaded fuel is not sold any more.
    I have two 1985 Honda NS 400 R that i raced and were not run for 10 years. the fuel system was totally blocked with thick red gunk which is the lead content from the fuel. Unleaded fuel is much cleaner.

    what model Ducati do you ride?
  5. monsterman

    monsterman Ol'Timer

    No you dont get 25% extra miles ,maybe 5% if your lucky but you get peace of mind because the system is getting cleaned and flushed and replacement injectors and pumps are expensive items
  6. HIKO

    HIKO Ol'Timer


    First of all I’m sorry that this reply is a few days late but I had computer and TT&T internet problems

    I saw that You are almost a Newbie on this board so maybe I am a little too rude to You now.

    But I’m tired of Newbies not bothering to do their homework before they send their posts. This time You didn’t have any questions which is already answered ten times before on the board but anyhow you could have bothered to look on the same thread 20 post ago.


    I think that I quite thoroughly explained octane ratings there and we don’t need to invent the wheel many times on this board.

    But I agree fully what you told about octanes.

    But I don’t agree what you wrote about Gasohol or as you called it Bio Fuel.

    Gasohol is low octane benzene blended with pure ethyl alcohol to obtain higher octane and a more environment friendly burning of the fuel. This is a fact which is scientifically proved many many times.

    Then you wrote:

    The real problem with using ethanol based fuels is the additives in the fuel.
    Thailand E fuel will over time result in the contamination of the fuel system and especially if the fuel is allowed to sit still for extended periods.
    Organic additive fuels will evaporate the same as pure hydrocarbon fuels evaporate but unlike hydrocarbon fuels the additive fuels leave a thin film of organic matter if the fuel is stagnate.
    If you check the underside of your bikes filler cap, you may find a discolouration of the metal. An orange to brown colour.
    If you leave the bike sitting long enough it will form a film and can be peeled off. Over time, it can completely block the fuel lines, injectors or carburettor jets.â€
  7. monsterman

    monsterman Ol'Timer

    My Ducati can and does use gasohol but my wifes rebel 250 cannot , we have purchased so called gasohol friendly carburettor and fuel system parts from USA but every time we put gasohol in the bike needs another carb rebuild so its regular or no go.
    long term gasohol deposits may yet cause problems so keep a wary eye out
  8. johngooding

    johngooding Ol'Timer

    I always follow this thread because I have an interest in any information on this subject which seems to polarise people into two opposed camps.

    I do not understand the need to be rude, especially to new posters who may well not be experienced in posting here, but may have valuable information to share. I feel that while you say you welcome more posts from Brian, the way you have responded is likely just to cause a flame war.
    Can we please be more civilised, by all means correct any innacuracies you see or add information but refrain from the personal critical comments, as it does not help other readers.
    And its not tiring to me to have another viewpoint on the subject

    And by the way I very much enjoy the technical nature and content of Hiko's posts. I am a Chemistry graduate retired from a career in the rubber industry, so I have a detailed knowledge of some parts of this topic, but little experience of the petroleum industry, which is where Brian works. So I would like to hear his views too.
  9. brian66

    brian66 Ol'Timer

    My statements in relation to Bio fuel were my opinion and to be taken at face value by those who choose to read my post. As I said “ My ten cents worthâ€
  10. HIKO

    HIKO Ol'Timer


    But I think you misunderstood me a little, I was not rude because Brian had an opposed opinion.

    I was rude because Brian, like many other Newbies didn’t do his homework before posting a post.. If he had bothered to read the earlier posts in this thread he would have find a post 24 rows earlier with the title WHAT IS OCTANE?. Here is exactly the information that is provided by Brian. The only new thing was the BMW anti knocking sensor.

    If Brian had an opposite opinion about the OCTANE matter or something to add he could have post it in connection with the earlier post. But by making a new post he tries to give the impression that he is bringing some new info to this thread. Actually he says so himself::

    “I would like to add my 10 cents worth of information to the fuel subject and hopefully give some useful information.â€
  11. HIKO

    HIKO Ol'Timer


    I sent my last post before I saw your reply which was very impressive. I will be happy to comment it but as You say yourself it is a little heavy so I will need some time.

    I look forward to have more discussions with You especially since You have an impressive background in the petroleum industry.

    The love and passion for motorcycles we share.

    Best Rgds

  12. johngooding

    johngooding Ol'Timer

    Hi Hiko,
    I appreciate your response and I see Brian has posted as well, it looks as if an interesting discussion may now result which I will be happy to follow, I was concerned that it may have gone a little agressive.
    I guess we all like to have something to contribute, and maybe if Brian had read all the posts he would not have put up his post, and what may become a good discussion may have not happened, so hopefully no harm done.
    Cheers, John
  13. HIKO

    HIKO Ol'Timer


    Now I will tackle Your very comprehensive reply. I will try to comment each of Your comments.

    1. On the Octane subject we totally agree. No opposite views.

    2. As you wrote Yourself : “Because I am relatively new to the web site I didn’t bother to read all the posts and unfortunately I never read the comprehensive explanation given by Hilco regarding all aspects relating to octane and the different fuels. I have just finished reading that post and I can say that it is a well thought through and very informative post by a person who is obviously experience and knowledgeable about this subject. I concur with all that is written.
    In fact if I had of read it first I would not have posted my own “10 cents worthâ€
  14. UHAUL

    UHAUL New Member

    Ok Would it be Rude of me to ask ( could you repeat all that ) :roll:
  15. DavidFL

    DavidFL Administrator Staff Member

    I need a week off to digest all of that. :oops:
    Thanks for making up with Brian. :)

    PICO-PICO Ol'Timer


    I beg to consider the following=
    a search on the forum for octane shows 29 results with a huge number of replies.

    Tell me which are the five most relevant posts to read?
    For which question precisely?

    This is only possible if an editor-censor assigns rankings to subjects and answers and consequently would eliminate irrelevant posts. Plus questions ought to be standardized. Desirable, possible?

    2. How do you search for a trip CM-Nong Khai?
    Exact question?
    Is it a North trip? Hardley.
    A search for Nong Kai yields 257 returns with hundreds of trip reports and thousands of pages.
    Tell me which one answers my simple question=
    which is the most scenic route CM- NK?

    Trip reports are very personal, hardly everything in them is of any relevance to the public at large.

    The solution would be only a standardized form demanding in telegram style basic info.

    That I would read with pleasure.

    Last not least you ought to leave it up to the responding person to take trouble of writing.
    Some people enjoy educating & sharing. And I have been reading with interest on similar subjects but viewed from a different angle.

    Repetitions is the key to learning. And there are no stupid questions, only stupid answers. E.g. I was amazed about the qualitative answers I got on my "bicycle underwear" question. 5 Answers and 144 people at least glanced at the subject.


Share This Page