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Thread: boost vs compression ratio

  1. #1
    What compression ratio's and boost are other teams running. We have seen 20psi boost with a static compression ratio of 13:1, however, piston meltdown occured quick.

    For those who have experienced piston meltdown, did the inlet or exhaust side top lands break off.

    William Attard
    MUR Motorsports, 00-04
    Retiring gracefully from FSAE

  2. #2
    ummm...

    how expensive is this getting william?

  3. #3
    Howdy Willy.
    We ran 6psi with standard comression ratio of kawasaki had no troubles at all.
    Cheers
    Ive gone to look for myself, if i get back before i return, keep me here.


  4. #4
    william, you running gas or e-85?
    jack
    College dropout extraordinaire
    (formerly WWU Rev-Hone Racing)

  5. #5
    Jack, were running 98 Octane pump fuel
    Retiring gracefully from FSAE

  6. #6
    William,

    What kind of turbo were you using?

    Silsport

  7. #7
    <BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> We have seen 20psi boost with a static compression ratio of 13:1, however, piston meltdown occured quick. <HR></BLOCKQUOTE>

    What did you expect.

    I cant imagine how high the cylinder pressure would of been.

  8. #8
    High cylinder pressure does not break pistons. From our cylinder pressure transducer trace, we had peak pressures of 120Bar, which from what I have seen is high, but workable.

    What breaks pistons is knock in the end gas region, which when speeds increase over 6OOORPM, the burn rates are so fast, that it basiclly doesn't have time to knock. In the old F1 turbo days, Honda ran 4Bar boost with a high compression ratio, and detonation wansn't an issue due to the high speeds.

    Our failure was due to poor mixture tuning as one cylinder ran leaner than the other, and we were sampling in the richer cylinder.
    Retiring gracefully from FSAE

  9. #9
    Surely though at that inlet pressure the increase in cylinder (and piston) temps due to the high compression are going to be extremely high.

    Probably why you melted the piston rather than detted it to death.

    Certainly would be nice to run 20psi though, only problem is that your restrictor chokes a lot earlier in the rev range.

  10. #10
    even thuogh this is an old post its probably worth mentioning knock did not melt your pistons pre ignition did

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