Flex fuel plug gap

  1. CTRdoc

    CTRdoc New Member

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    Location:
    Stuart,Fl
    First Name:
    Gerry
    Car(s):
    Civic Type R
    Was going to add a Siri Moto flex fuel kit to my type R . I’ve read about spark plug blow out and was wondering what is the best spark plug and spark plug gap. Can the stock plugs just be re gapped
     
  2. 06S2k07Si

    06S2k07Si Senior Member

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    Location:
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    Brian
    Car(s):
    2006 S2000 2007 Civic Si 2008 TSX 2014 TSX 2013 CB1000R 2018 Civic Type R 12063
    Yes the stock plugs can be gapped. A gapping tool like this can be used... https://www.amazon.com/gp/product/B07PFC9X17/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

    Just FYI...

    Age of ignition coils can play into this quite a bit...ambient temperature can play into this very notably as well. As the ambient temperature gets colder the air gets more dense and the energy required to jump the gap increases. In general you should run the largest gap you can RELIABLY. Elevation will also play in...the higher the thinner the air and less dense etc.

    For one point of reference...

    My 2006 S2000 had several iterations of supercharger kits over the years. When it was on the original Krafwerks kit (C30-94 blower) things were initially fine at right around 10psi of boost with .032" of gap. As the temperature dropped below approximately 40 degrees Fahrenheit I would get some breakup up north of 7k ish rpm. I lowered the gap to .026" and it completely went away...all on 93 octane. When we installed the first iteration of my TTS kit (C38-92 blower) around 16psi it needed .024" gap...until the temp got below around 40 degrees Fahrenheit...breakup started and we dropped it to .022" and again the problem dissapeared. When we reworked all of the piping and the boost increased to 17-18psi it needed .020" all still on 93 octane fuel...until we retuned it on E85 and it wanted .018". All with the same BKR8EIX plugs. Today it still is at .018" on E85 and seems fine. This is all on my car which I am the original owner. The first kit was installed at just over 5800mi and now has 29,000mi. All still with the original OEM ignition system and coils.

    I hope this helps.

    Brian
     
  3. OP
    OP
    CTRdoc

    CTRdoc New Member

    Joined:
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    Location:
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    Car(s):
    Civic Type R
    Thanks for the help. Didn’t realize all those variables can affect it.
     
    06S2k07Si thanked this.
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