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Spring E85 question

Discussion in 'The Distillery' started by Klaus, Apr 4, 2021.

  1. Klaus

    Klaus Premium Member Premium Member Established Member

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    I took my gt500 out yesterday after sitting all winter. It started right up, no problem. When I parked it in October it had a full tank of E at 78%. When I started it up the E was only at 72%.

    To increase my E content I filled it up at the place where I always go and it actually dropped my E content. Now I am sitting with a full tank at 68-69%.

    What to do? My CR is 8.5 and my boost is set at 24 lbs. I assume it will be OK if I stay out of the boost.
     
  2. Weather Man

    Weather Man Persistance Is A Bitch Premium Member Established Member Top Shelf Gentlemen

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    You should be fine.
     
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  3. 2011 gtcs

    2011 gtcs GT500 poster Established Member

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    Usually E70 to E85 you're good to go. E68 is definitely getting a little low. But if you have a nGauge or something to monitor your knock sensors I would keep a eye on them.
     
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  4. 11Sec_Lx

    11Sec_Lx Well-Known Member Established Member

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    I see five quick options:

    1) drive the fuel out, staying out of boost
    2) remove the fuel and replace
    3) get a tune for the 68% or whatever it's at
    4) pull a few degrees of timing (if you can)
    5) reduce wot boost by 2-4lbs with a larger pulley

    My $.02

    Sent from my SM-G988U using Tapatalk
     
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  5. c6zhombre

    c6zhombre E85 NutSwinger Established Member

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    When you are originally tuned for spot on 85% and you get a tank of % less than that, the motor will run RICH

    When you are originally tuned for 85% and you get a tank of % more than that, the motor will run LEAN

    It's up to you and the tuner to decide what's too rich or too lean to neccisitate a revised tune to handle the difference.

    Keeping an 85% tune and a 65% tune at minimum should cover most bases.
     
  6. Dusten

    Dusten Well-Known Member Established Member

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    Its about more than the AFR. The octane difference and timing needs to be addressed.
     
  7. c6zhombre

    c6zhombre E85 NutSwinger Established Member

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    There are plenty of 8.5/1 03/04 Cobras making 800+ with E70 and a gen 4 or gen 5 whipple. And not just putting around, either....running 1/4 and half mile events with high timing. I think the op will be just fine with E69, it still has a massive amount of detonation suppression and even burn across the top of the piston. Ethanol % has to fall further than that before you start panicking.

    But ask the tuner as I've already mentioned. Maybe he makes a slight adjustment that can be kept for future reference.
     
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  8. gimmie11s

    gimmie11s Don’t be an idiot Established Member

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    at 68-69% E content, the mixture is actually richer now than it was at 78%.

    You still have an incredible amount of knock protection with damn near e70 (effectively what is in your tank).

    I wouldnt sweat it.
     
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  9. Dusten

    Dusten Well-Known Member Established Member

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    I didn't say it is unsafe. I said the change in octane is more concerning than afr.

    And I run e85 and make 700+ on a 2v that beat the **** out of.
     
  10. Weather Man

    Weather Man Persistance Is A Bitch Premium Member Established Member Top Shelf Gentlemen

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    The knock reduction protection of E85 is non-linear. Most of the protection is achieved by E50.
     
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