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  1. #1

    What octane to run with 9:5:1 pistons?

    Rebuilt my engine using CP 9:5:1 pistons and Carillo rods. I have a et137 wheel so it's at about 15 lbs boost max. My question is what gas do I run? Will I be safe on 92 octane?

    Has anyone using 9:5:1 pistons had a problem with detonation?


  2. #2
    tiderider's Avatar
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    It depends on the tune and ignition timing for which fuel you decide to use. It will fail with just a stock tune. I always use 8.4:1 pistons.

  3. #3
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by Smashrockwell View Post
    Rebuilt my engine using CP 9:5:1 pistons and Carillo rods. I have a et137 wheel so it's at about 15 lbs boost max. My question is what gas do I run? Will I be safe on 92 octane?

    Has anyone using 9:5:1 pistons had a problem with detonation?
    We need more info on your ski: what ECU, Maptuner/datalogging or other?

  4. #4
    2006 RPX ECU
    Maptunerx
    Supertech Valve train, valves springs and retainers
    ARP head studs
    Schnielder cam Stage 3 http://schneidercams.com/Stage3SC_SeaDoo-1.aspx
    Cp Pistons 100 mm 9:5:1
    Carrillo rods
    215 flywheel with ARP bolts
    X charger with a ET137 wheel
    08 oiler mod
    160 thermostat mod
    Fizzle 1000 intercooler
    Riva Vt1100 injectors
    Free flow exhaust
    Flame arrestor removed from intake
    4" air intake
    Water strainer
    Aluminum pump

    Planning on running the riva 2009 RXT IS 255 STAGE 4 tune but I have 9:5:1 pistons.

    Let me know what gas u think I should run?

  5. #5
    I haven't started the ski yet. I have maptunerx but no data logger, yet.

  6. #6
    tiderider's Avatar
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    You'll need a logger to adjust tune. I would put minimum 93 in it at first. I would have used 8.4:1 pistons, best stable bet. If its a siemens ECU, you won't be able to adjust or view timing with a logger as well. 8.4:1 would have simplified this and its timing which very much needs to be adjusted for 9.5:1 pistons.

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  8. #7
    Bob 1tommygunner1927's Avatar
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    Quote Originally Posted by Smashrockwell View Post
    I haven't started the ski yet. I have maptunerx but no data logger, yet.
    Use the highest pump octane available. Suggest adding Torco Accelerator to pump gasolines.
    https://torcoracefuel.net/collection...co-accelerator

    According to Riva, they can provide custom tunes for Seimen ECU's, contact Jesus at Riva for that purpose.
    https://www.maptunerusa.com/tuning-library/tuning-library-pwc/sea-doo-library/seadoo-siemens-ecu




    Last edited by 1tommygunner1927; 07-23-2021 at 12:47 PM.

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  10. #8
    tiderider's Avatar
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    This is what you'll get to see with a PLX for AFRs and Maptunerx for logging. No ignition timing is displayed. Siemens 2006 ECU, its on Riva's library list.

    Time AFR Volts ManifoldAbsolutPressure BatteryVoltage NoiceLevel EngineRPM WaterCoolantTemp IntakeAirTemp ExhaustWaterTemp ThrottlePosition Idle Status IACVPosition
    s AFR V PSI Volt * rpm C C C Deg * * *
    4.45 14.2 13.45 9.48 13.4 33 1712 70 32 55 0 9 32 98
    4.6 14.5 13.43 9.51 13.1 40 1777 70 32 55 0 9 32 99

  11. #9
    suck my wake's Avatar
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    I've run 93 with the 9.5-1 pistons with the Riva Racing ECU in my 06 with no issues and that was with the 3 rude charger spinning 8600 rpms but I did have a bigger fuel pump with a return loop system running 65 psi with boosted regulator..... 1 point in compression isn't that huge but it does make it that much more important that you use premium fuel and have a good fuel system. At higher boost or Rpms than that I would recommend 100 octane

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  13. #10
    tiderider's Avatar
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    NOTE.. with a Riva Racing ECU.. Not with a flashed Siemens ECU with maptunerx.

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