Measured distortion on 308 sleeves with torque plate | FerrariChat
Buy

Measured distortion on 308 sleeves with torque plate

Discussion in 'Technical Q&A' started by luckydynes, Nov 27, 2007.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, Skimlinks, and others.

  1. luckydynes

    luckydynes F1 Rookie

    Jan 25, 2004
    3,931
    CA and OR
    Full Name:
    pit bull
    #1 luckydynes, Nov 27, 2007
    Hey all,

    Measured how much the sleeves might be moving when the heads are torqued up:


    Top of ring travel grows .001" in direction of skirt, shrinks .001" normal to this

    Approximate bottom of ring travel grows .002" in direction of skirt, shrinks .002" normal to this

    Bottom of bore grows .002" in direction of skirt, shrink .003" normal to this


    There was a little difference between the "inner" and "outer" sleeves . ..

    Should I:

    1. Bury my head in the sand and not worry about the distortion . . . did this before but if there's power to be gained I want it. I haven't seen any oil consumption but leakdown isn't 5% like I wish it was. That motor made 210hp at rear wheels with stock cams, EFI system, and high compression pistons.

    2. Modify my fixture to distort the bores the same way . .. I did a little fiddling and think I can simulate the distortion within .001" ... especially at the top of the bore which might be the only place it's critical for ring sealing?

    3. Just rough bore the cylinders with the fixture as is and have the block torque plate honed.


    On other motors, (Chevys, anything) can anyone report on power increases they saw when torque plate boring? Also how much distortion do these other motors see in the bores?

    Thanks,

    Sean
     
  2. mk e

    mk e F1 World Champ

    Oct 31, 2003
    13,814
    The twilight zone
    Full Name:
    Help me get this thing finished! https://gofund.me/39def36c
    #2 mk e, Nov 27, 2007
    This may not apply exactly, but in my QV the leak-down was less than .5% at 100psi just dropping the liners and running it. It’s pretty much the same block so I would assume I had similar distortion. I used total seal rings with a gapless 2nd compression ring. I’ve had very good luck with them. I had to re-groove my pistons to use them though because 1.5mm was as thin as they did gapless, at least at that point in time.

    Of the options listed, I like finishing in place with torque a torque plate the best.
     
  3. tomoshea

    tomoshea Formula Junior

    Dec 29, 2003
    541
    Ireland
    Full Name:
    Tom O'Shea
    #3 tomoshea, Nov 28, 2007
    the guys in Superformance in the UK indicated to me that they use a torque plate to the specified torque and then bore liners out with the torque plate in situe to the required diameter. They say this ensures that there is no distortion and no risk of any smoking after a rebuild. They have been doing this for 20 years.

    Not what Ferrari recommend, but I know at least 5 people that have had engines rebuilt by them using this method, all are fine. They use 10.5 compression JE pistons for the rebuild.

    Sending my bottom end over to them in Janaury for high compression pistons to be fitted.
     
  4. luckydynes

    luckydynes F1 Rookie

    Jan 25, 2004
    3,931
    CA and OR
    Full Name:
    pit bull
    #4 luckydynes, Nov 28, 2007
    Less than .5% or 5%? Did you measure the sleeves before putting them in? I'm assuming they're Nikasil on 4 valve so you wouldn't have bored them . . . just curious if they were in fact round.

    Thanks,

    Sean
     
  5. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,277
    socal
    #5 fatbillybob, Nov 28, 2007
    torque plate/bore
     
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    13,814
    The twilight zone
    Full Name:
    Help me get this thing finished! https://gofund.me/39def36c
    #6 mk e, Nov 29, 2007
    0.5% on the worst on. 6 or them were 0.0%. I had the sleeve re-conditioned and put them in , seat the rings and the engine seals, I've had very good luch with gapless rings.

    My buddy did a way over bored harley that ran good. when he pulled it apart for more mods he discovers the cylinders with bother out of round about .020", but it had almost no leak-down (gapless rings). Everything had worn inot the shape. So horrified, he cleaned up the bore, got new pistons and back together, the next tear down the cylinders were .020 out of round - he had bored the cylinder right out into the fits before pressing in the new liners and that little section on exposed sleeve was causing the cylinder to go out od round the best we could figure. But it ran just fine.
     

Share This Page