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Horizontal Piston - Oil Ring Orientation

Discussion in 'Technical Q&A' started by Kevin Rev'n, Jan 19, 2016.

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  1. Kevin Rev'n

    Kevin Rev'n Two Time F1 World Champ
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    #1 Kevin Rev'n, Jan 19, 2016
    Does it matter where you orient the seam for the oil control ring on a horizontal cylinder? How do you guys orient the ring? Down, Up, Side?

    It doesn't say in the manual but something tells me that it might matter.
    It's a two compression one oil ring set up and I know to orient them 120 degrees from one another but not sure where to put the oil ring seam....or if it matters.
     
  2. doug_porsche

    doug_porsche Karting

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    #2 doug_porsche, Jan 19, 2016
    If I remember correctly, (and I am remembering Porsche, not Ferrari), have the compression gaps at 10 and 2 and the oil at 12.


    Looking forward to see if I remember correctly.
     
  3. Kevin Rev'n

    Kevin Rev'n Two Time F1 World Champ
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    #3 Kevin Rev'n, Jan 19, 2016
    Oil at 12 makes sense to me if the purpose of that ring is to keep the oil in. When at rest the oil should accumulate at the bottom. The thing I am unsure of is if there is a secondary function of the oil ring to allow "some" small amount of oil to work past the small gap and provide some benefit to the other two rings!

    I may be over thinking this because the other cylinder in my application is straight up and would not be able to provide any extra pass though of oil other than what was distributed on the cyl walls below the piston.
     
  4. ago car nut

    ago car nut F1 Veteran
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    #4 ago car nut, Jan 19, 2016
    Piston rings move in use, or a groove would be worn in the cyl.
     
  5. Kevin Rev'n

    Kevin Rev'n Two Time F1 World Champ
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    #5 Kevin Rev'n, Jan 19, 2016
    See! Over thinking it! :)
     
  6. Kevin Rev'n

    Kevin Rev'n Two Time F1 World Champ
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    #6 Kevin Rev'n, Jan 22, 2016
    Someone made me aware of this article if anyone is geeking on my query. :)

    Credit - Ducati.ms (Think of it as the Ducati Chat of the motorcycle world)

    "Monitoring of Rotational Movements of Two Piston Rings in a Cylinder Using Radioisotopes"

    http://kns.org/jknsfile/v31/A04803285773.pdf
     
  7. Jumprun

    Jumprun Karting

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    #7 Jumprun, Jan 22, 2016
    Just don't line the gaps up, I too learned the 10, 12 and 2 o'clock orientation for Porsche engines.
     
  8. finnerty

    finnerty F1 World Champ

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    #8 finnerty, Jan 22, 2016
    Last edited: Jan 22, 2016

    Exactly. Ultimately, it does not matter as the mass / inertial + frictional properties will cause the rings to "settle" to their final orientation on their own.

    That said, good practice for initial startup purposes (regardless of engine configuration) is to offset all the gaps by at least 30 degrees from one another so that initial loading is well distributed. Particularly, if you are also starting with fresh (or at least "freshened") cylinder walls and pistons.

    When you pull pistons from any engine that has been in service for a awhile, you will observe the "settled" positions of the ring gaps to be all over the place, and not consistent at all from cylinder to cylinder. Some of that is from wear patterns, but the bulk of it is from the inertia of the parts.


    .
     

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