Results 1 to 4 of 4
  1. #1
    Member
    Join Date
    Mar 2006
    Location
    Prosperity, SC
    Posts
    1,141

    93 Octane for break in?

    From what I understand 93 burns hotter. So would that be a better choice for setting the rings?




  2. Member
    Join Date
    Feb 2018
    Posts
    3,153
    #2
    I have seen no evidence of higher octane burning hotter. Or colder.

    Why should it? Octane is merely the resistance of gasoline to auto-ignite. It is not about burn temperature or rate.

    There is no one substance that is added to gasoline to change the octane rating. Many substances can be used. Ethanol. Tetraethyllead. Each may have its own effect on burn temperature and rate.

    In my controversial opinion, follow the Mercury Marine break in procedure as the better choice for breaking in a new motor.

  3. Member
    Join Date
    Jan 2012
    Location
    Jackson, Tn.
    Posts
    1,955
    #3
    Fuel with an 87 octane rating burns more quickly while higher octane ratings burn more slowly. Said another way.....the higher the octane, the harder it is for the fuel to ignite. If it doesn't knock or ping.....go with the lower octane rating.

  4. Member
    Join Date
    Jul 2014
    Location
    KALKASKA MICHIGAN
    Posts
    4,065
    #4
    Quote Originally Posted by davesz518 View Post
    Fuel with an 87 octane rating burns more quickly while higher octane ratings burn more slowly. Said another way.....the higher the octane, the harder it is for the fuel to ignite. If it doesn't knock or ping.....go with the lower octane rating.
    The first part of this is wrong. The second part is correct. Yam911 is spot on with his statement. Sunoco has very good info on all of this on their site, do some reading there for up accurate info. They are helping to figure out what fuel would be best for a 16 to 1 engine at 8k rpm in just a bit. I was shocked to learn that a 12k rpm indy car engine only uses fuel with a high 80's octane but a extremely fast burn rate for the RPMs they turn. A prostock engine of past days uses a fuel with 118+ octane because of the compression but has a extremely fast burn rate because of the 11+k rpms they "used to" turn just like the indy car engines, they are now limited to 9.5 or 10k I believe. I am only turning up to 9k but have to have a bit slower burn rate because of "only" running 8-9k max. CJ
    Last edited by CJ1; 09-10-2021 at 09:04 AM.
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.