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Piston Ring Selection.

Discussion in 'The Garage' started by colbystephens, Oct 10, 2005.

?

I should use . . .

  1. standard cast rings

    4 vote(s)
    25.0%
  2. moly rings

    12 vote(s)
    75.0%
  1. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    As some of you may know, i'm building a 6.2L diesel motor. i need to order my piston rings, and after some research have decided that the cast rings will accomplish the job just fine. i'm wondering if there's any different opinions out there and why. i've read that it's very difficult to get the moly rings to seat properly, and since this won't be a super high power/high rpm motor, i figure the cast rings are fine. when you are deciding on your opinion, please keep in mind that someday in the future i intend to turbo this motor. thanks!

    ColbyStephens
    www.web.pdx.edu/~colbys
     
  2. Big89Burban

    Big89Burban 1/2 ton status

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    I rebuilt the motor in my 83 3/4 ton 6.2l. Used all stock stuff. Thats probably what I would go with again. Since the diesels can go so far just on stock stuff I really wouldnt worry much. Just make sure to gap them correctly! :D
     
  3. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    thanks for the input on the stock stuff. in spite of the poll, i think that's the direction i'm going.

    however, it's not too late to change my mind. :)

    Please, those of you who are voting moly rings, please specify why you choose them.
     
  4. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    For my gas engine 4.3l V6, I choose moly (moly, not chrome moly). I did alot of reading before I chose those, and I can't say I've heard anything about them being difficult to seat. I've read they seat much much quicker and better, and have better oil retention and have higher resistance to scuff. I did read you can screw them up more easily on installation (they chip easily if you catch an edge going in the bore), and if you don't follow the proper break in procedure for them, they can get ruined or your cylinders glazed. The break-in procedure I read for moly is on first start, keep it at 2000rpm until operating temp, that's normal, time it, carb adjustments, then go out on the road and do several 1/2-3/4 throttle line launches and at speed launches. After that, so I've read, they are pretty much seated with varying throttle driving after 500-1000mi. Let it idle too much less than 100mi, or sustained cruising at any speed, and you'll do 'em fairly quickly. I've read cast rings can take up 30,000mi to seat.
    Just what I've read in various places, mostly books, some internet articles and some internet forums. So take it at face value.
    My little v6 is running great at 1400mi, dyno pulls show 242hp@4800 and 259ft'lbs at 3750. I didn't go wild either, just 1 up cam from stock and vortec heads from a 2004, edelbrok manifold and holley 390cfm carb. Getting 22mpg already in the C10 truck it's in, and no blue smoke.
    I never did any reasearch on rings for diesel engines, so can't really say if moly is a good choice there or not.
     
  5. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    I appreciate the reply - it's good to think about. I'm not sure if I'd be able to do the break in procedure you described quite accurately. I don't have a tachometer and I don't know if 2000 rpm would be right for a diesel which maxes out at 3600 rpm - maybe, just more to research i guess. thanks.

    colbystephens.
     
  6. 73k5blazer

    73k5blazer Unplug the matrix cable from the back of your head Premium Member

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    Yeah, the 2000 was for a regular gas engine. I would do some research to see what break-in procedures are recommended for diesel engines.
     
  7. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    the hanes manual for this motor describes how to go about it. i figure i'll just follow that - any reasons i should consider following another method?

    colbystephens
     
  8. 79chevyk10

    79chevyk10 1/2 ton status

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    When I built my motor I went for the cast rings, mainly due to the fact that I wanted oil control, I didn't want it going through any oil between changes and I was not building a race motor where coeffiecent of friction was a big concern. There is a place for all motor parts. You have to decide on what you expect to get out of your motor.
     
  9. 1-ton

    1-ton 1/2 ton status Premium Member

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    I would go for the cast iron rings too. It takes longer for them to seat in, but they will hold compression for a long time after they are seated. Cast rings are also easer to deal with when installing them too. Moly rings can be very sensitive to incorect installation, or a bore that is not perfectly round.
     
  10. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i appreciate all of the input. i went ahead and got the cast rings. diesel piston rings are freakin expensive! i suppose everything else on a diesel is too, but whatever. i got $200 off, and it was still a huge cost. oh well. the price you pay for something you love to do.

    cheers.
    colby stephens
    www.web.pdx.edu/~colbys
     

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