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100 Octane in 355?

Discussion in '348/355' started by butcher, Apr 8, 2010.

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  1. butcher

    butcher Formula 3

    Oct 19, 2008
    2,339
    Castro Valley, CA
    Full Name:
    Albert
    #1 butcher, Apr 8, 2010
    Anyone have any experience using higher octane fuel like 100 octane in their 355? There is a local station that offers 93 to 100 octane at the pump and I was intrigued about possibly trying out the higher octane fuel if there are definite benefits that others have noted in their 355. Did you get any increased performance, acceleration, mid-range power, etc? Was use of higher octane gas a waste of money due to no performance gains? And probably most important, Did the use of these higher octane fuels cause any harm to your 355? If anyone else has any useful information in regards to the efficacy and safety of use in our high revving, Valve guide issue, Manifold issue, and Catalytic convertor issue cars, please chime in.

    I used the search engine and found only one prior post on the issue that did not answer any of these questions specifically in regards to the 355:
    http://www.ferrarichat.com/forum/showthread.php?t=38875&highlight=100+octane+gasoline
     
  2. vvassallo

    vvassallo F1 Veteran

    Aug 4, 2006
    8,324
    Palos Verdes
    Full Name:
    Vince V
    #2 vvassallo, Apr 8, 2010
    You engine is designed to handle premium fuel octane which means 93-95, although 91 is okay for our poor CA-located cars. Since the car is not tuned for 100 you are not going to see any benefit, IMO. Now, if you had your ECU modified for the extra octane (like with a more aggressive advance) you would see some (small) benefit. On the track, every bit helps. :) You would probably feel more of a difference between 91 and 95 than 95 and 100.
     
  3. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,721
    #3 Mitch Alsup, Apr 8, 2010
    I have used 104 no-lad at the race tracks (and as long as it lasted on the way home). The car runs with ever-so-LESS power but smoother. Then once you run this tank of gas out of the tank and fill with the normal stuff, the ECU takes 50 miles to figure it all out agoin with a big stumble as you pull away from the station.

    A: So if you listen well, you can hear a change in note of the engine
    B: you are making less power, not more, even after the ECU learns the new fuel MAPs
    C: when you go back to normal fuel, the ECU has to UNLEARN the high octane stuff

    I suspect the ECU learns how to advance the timing with the HO stuff and it might diddle with the fuel trims. Then when you refill the ECU gets knock sensor "data", so it jumps back to "save the engine" mapping and learns its way back out to where it used to be.

    96 octane race gas runs slightly better in my car than 104 no-lead, and avoids the refill headache.
     
  4. butcher

    butcher Formula 3

    Oct 19, 2008
    2,339
    Castro Valley, CA
    Full Name:
    Albert
    #4 butcher, Apr 10, 2010
    Used the 93 octane during our last "run" with other F-car and exotic owners today. 93 Octane seemed to make the car run smoother with possibly only a mild increase in performance noted. Car ran well today, but I can't truly say a large gain was noted. I can say that it ran as well as it ever has. It can't be too bad when I'm able to keep pace with the Scuds and 430's of the group.
     
  5. lndshrk

    lndshrk Formula Junior

    Nov 7, 2003
    753
    SLC, Utah
    Full Name:
    Jim Conforti
    #5 lndshrk, Apr 10, 2010
    A modern single-fuel ECU, like M5.2 will not "advance" the ignition timing.

    it has a programmed map (or maps) from which it will RETARD the ignition timing if it senses detonation.

    So using higher octane fuels than the vehicle is tuned for does little but lighten the wallet.

    Tuning for any particular fuel takes into account:

    1) Oxygen content and stoichiometry - which sets the AFR

    2) Burn rate (at that specific AFR) - which sets the ignition timing (in some cases - limited by)

    3) Octane rating (resistance to detonation - useful in a knock-limited situation)

    (above all highly simplified - but you get the idea)
     

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