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Thread: High RPM Detonation?

  1. #1

    Question High RPM Detonation?

    Yesterday at the SCCA Event as I was riding along with my co-driver I noted the car sounded like it was detonating at high RPMS?? We had put super in it the day before.

    It was a bit toasty yesterday and the turnaround time between drivers was quick. Not sure if that playing into the noises I was hearing. I know my co-driver was not being timid with the gas at this event. The temp gauge never moved.

    Thoughts or suggestions??

    I'm also thinking of switching the car over to E85 like my pal OZMDD would that help??

  2. #2
    Team Cheap Bastard
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    Check your timing.

    PS
    We all know you suck at reading the flywheel gauge.

  3. #3

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    Quote Originally Posted by sammm View Post
    Check your timing.
    I'll double check it but it has been set since I resurrected the car.

  4. #4

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    Quote Originally Posted by sammm View Post
    PS
    We all know you suck at reading the flywheel gauge.
    An that is why I haven't touched it since we last figured out how to set it!

  5. #5
    Orange cones fear me. cone-cerned's Avatar
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    I'm assuming the Super was 93 octane. I don't think a timing bump would cause detonation with 93 octane. When is the last time you cleaned your pistons? Maybe Seafoam would help.
    On the track, I am fearless.
    If you were as slow as me, you wouldn't be afraid either.

    1994 M Edition
    CSP 67

  6. #6

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    It was 93 but like I mentioned I haven't adjusted anything on the car in recent history since I am a huge fan of the "If it works don't fvck with it" program.

    It is about due for sparkplugs . But it has run on several other porly designed Jimmy Jan courses when I was up in the high RPMS for longer than my co-driver was yesterday and I never noted the detonation.....

  7. #7

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    I'd try Seafoam + a new fuel filter.
    "Pain is inevitable, suffering is optional." Haruki Murakami

  8. #8

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    Cheater motor!! Didn't I mention the 15:1 pistons when I sold it to you?
    What's left of a '96 Miata with stock clutch.
    My car exceeds my driving ability. That's the only possible explanation.

  9. #9

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    Quote Originally Posted by Mark52 View Post
    Cheater motor!! Didn't I mention the 15:1 pistons when I sold it to you?
    I'm just glad I bought the extended warranty!

  10. #10

  11. #11

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    Banana in the tail pipe?

  12. #12

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    Would this be a spark plug heat range issue perhaps??

    Not that I know anything about spark plug heat ranges....

    http://www.ngksparkplugs.com/tech_su...2.asp?mode=nml

  13. #13

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    I have some electronic detonation headphones/amplifier if you want to borrow them short-term. You clip it on to the block and have a listen, you'll be surprised with what you hear. email me if you're interested.
    TXMC: Drinkin, shootin, racin!

  14. #14

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    mr. brg I don't think I'm skilled enough to know what your very cool electronic detonator headphones/amplifer would tell me.... But I greatly appreciate the offer.

    First off I'm going try a few simple things I just got from Rockauto.com


  15. #15

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    lol

    You take the big aligator clippy, clip it to something on the block, flip the power button to "on", plug in your headphones, and listen for detonation.

    They do a really good job of broadcasting combustion irregularities. The provide enough resolution that I managed to tune spark on a dyno that did not read output that day (bad dyno firmware) remarkably close to an "expert tune". We're talking so close that I did not go back and alter the table I made.
    TXMC: Drinkin, shootin, racin!

  16. #16

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    Well old plugs all looked exactly the same and didn't find any surprises when I changed the plugs and wires.

    I'd classify them as normal based on this chart - http://www.ngksparkplugs.com/tech_su...qs/faqread.asp



    No telling how old the fuel filter was but I can tell you when you are hot and sweaty and the gas runs down your arm into your armpit it creates a sensation that could be best classified as "undesirable".....

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