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Head gasket for higher comp?

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    Head gasket for higher comp?

    Hi guys,

    Tried the search function, but couldnt really find anything on this subject.

    I'm planning on replacing my head gasket, along with ARP studs for a current track/hpde project.

    I come from Honda time attack builds and there are a few companies out there that offer a thinner gasket for a safe n/a build...so pardon my ignorance!

    What is a popular head gasket thickness that is ideal for an NA 91 octane track build? Stock bottom end. I have a contac at Cometic through my work, and I'd like to go with one of their ''custom'' thicknesses.

    Thanks in advance!
    Eibach

    #2
    I haven't come across anything THINNER than stock, at what, 1.3, 1.5 mm? There is a THICKER one...

    If your head's ever been skimmed and/or had valve work, it's well- worth cc'ing it to see where your volumes are- someone else will have to chime in with what you're looking for...

    t
    now, sometimes I just mess with people. It's more entertaining that way. george graves

    Comment


      #3
      With a stock bottom end and a head shaved to the max the CR will 9.0-9.1. Hardly high compression. Nor will a thinner gasket bump the CR enough to justify anything greater than 89 octane (with the right tune).
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

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        #4
        Thanks guys. I'll just stick with an oe replacement.
        Eibach

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          #5
          Jim, just out of curiousity,
          what octane do you race on?

          t
          now, sometimes I just mess with people. It's more entertaining that way. george graves

          Comment


            #6
            Originally posted by TobyB View Post
            Jim, just out of curiousity,
            what octane do you race on?
            87 octane except in the hottest weather where I use 89 octane.

            Since the class allows for no mods of the engine management, I am stuck with the stock ignition timing. The engine would run better with more spark advance, even on 87 octane. Running a higher octane fuel would just make the lack of advance worse.
            The car makes it possible, but the driver makes it happen.
            Jim Levie, Huntsville, AL

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              #7
              Toby, gotta remember Spec E30 is a lot stricter as far as engine mods then PRO3. They actually have rules as far as horsepower output and use dyno tests to verify. Unlike PRO3 where everyone is too buddy buddy (or scared to become an outcast) to protest cars working in the gray area of engine mods.

              If the M20 is truly spec, then pump gas should be fine with even the legal chips we run. That being said, I run non-ethonal Premium in my car. You have to hunt around for stations that carry it (or have a commercial fuel account), but I do notice a difference in how the car runs, and fuel burn.
              1991 325i MT2 Touring (JDM bro)
              2016 Ford Flex
              2011 Audi A3 - wife's other German car

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                #8
                Thanks, Jim-
                I'm also bone- stock, and came to the same conclusion-
                on a low- compression motor with conservative factory timing, 87 should
                make more power. It does in the tow rig!

                I came from a 12:1+ engine class, so it just feels... wrong... but
                logically (and scientifically) it will work.

                Jeremy, I'm running a 160k bottom end, uncut head, and stock 524 ECU.
                No grey area here, just a serious DCR car. Or, rather, a DFL DCR car, as evidenced
                by last weekend's results.
                Annoyingly, all of you keep getting faster, while I seem to be keeping a respectable
                time for mid pack... in 2006...

                t
                now, sometimes I just mess with people. It's more entertaining that way. george graves

                Comment


                  #9
                  Hey, my lap times would have put me in the lead 4 years ago. I don't believe the majority of the field is playing in the grey area.

                  But that might change at the end of the year due to some rule changes in the works.
                  1991 325i MT2 Touring (JDM bro)
                  2016 Ford Flex
                  2011 Audi A3 - wife's other German car

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