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Wiseco piston balancing limit / location

Posted by willyp42, Jun 29, 2020 at 10:04 PM

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  1. willyp42

    willyp42 Probationary Member

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    Hey guys I just finished up weighing my pistons, wrist pins, and rings and found I have a 1.5 gram weight difference max to min.

    do you guys think it’s safe to take the 1.5 grams of the inside of the pin boss?

    upload_2020-6-29_23-3-18.jpeg

    I was going to put a gentle chamfer there.
    Thanks,
    -Will
     

    Attached Files:

  2. DSMPT

    DSMPT Proven Member

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    It wouldn't be a problem if not too much. I always take some material from there. You can combine the heaviest piston with the lightest rod (or vice versa) to make the weight difference minimum. Also you can remove some material from rods and wrist pins to make the total weight equal to avoid removing too much material from the same location on the same part.
     

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  3. willyp42

    willyp42 Probationary Member

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    Yeah I get you, I wouldn’t feel concerned if it was a half gram, but 1.5 seems excessive I wonder if anyone else has experience here?
     
  4. DSMPT

    DSMPT Proven Member

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    If you would remove 1.5g material from only the boss where you marked then it may be too much. Just making chamfer on the boss would probably reduce only approx. 0.1g~0.3g. But how much material you can safely remove would depend on your setup though. Please see the pic below, I removed material most from the #2 piston, the removed weight was approx. 0.5g, now you can guess how much material would be 1.5g.
    DSC_1303.JPG
     

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  5. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    You are fine with a 1.5 g difference, but it won't hurt to try and get it closer.
    What is the combined weight of the 1-4 throw compaired to the 2-3 throw?
    Add 1 and 4 together and add 2 and 3 together to see what the total throw weight difference is.
    I have a 1.5 gram spread but only a .5 gram difference in throw on my motor and she runs fantastic.
    You can open and look at these last 3 builds for reference if you want. The last 4g motor (MW2) is a 7 bolt and has super close weights, so close that I suspect the lower end was balanced at one point, I just rebuilt it for my son.
     

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  6. willyp42

    willyp42 Probationary Member

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    #1 482.69
    #2 481.30
    #3 482.10
    #4 481.33

    1&4 984.02, 2&3 963.40

    i still haven't weighed my rods yet, but i am looking to take full advantage of my Kelford 276HL cams. i plan on spinning it to 8500. its the reason why id like to be tight on my reciprocating mass.
    -Will
     
  7. DSMPT

    DSMPT Proven Member

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    So you haven't weighed the rods yet... then don't take any material from the pistons yet. As I said above that how you combine the pistons and the rods would change the weight difference. After you weigh everything and calculate all combination weight should be the moment to start thinking how much material you need to remove.
    By the way, the Kelford 276HL is a bit peaky but a good set. I used to run them for some years and I liked them.
     

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  8. motomattx

    motomattx Proven Member

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    You would want your small end weights close to each other and the same with thee big ends, not necessarily the overall weights but the ends are more important and in doing that you would get the overall weights pretty close by default.
     

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  9. willyp42

    willyp42 Probationary Member

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    so optimized rod weight tolerance stack for total recip mass wieghts.
    1103.97
    1103.44
    1103.60
    1103.43
    i dont disagree with motomattx, however i dont have access to a rod weighing apparatus.
    i tried calling 2 of my local machine shops but they arent able to get to it.
    i think im just going to take 3 tenths off heavy cylinder and run it.
    thanks guys,
    -Will
     
  10. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    You probably won't notice the difference but you are getting it as close as you can.
    Those cams will take you to 9k, BTW.
     

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  11. willyp42

    willyp42 Probationary Member

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    Thanks for response,
    I’ve had this apart for so long I don’t remember the hardware limitation reason I believe it’s my rod bolts.
    -Will
     
  12. DSMPT

    DSMPT Proven Member

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    It's ideal but it's not super necessary to run. As @1990TSIAWDTALON Marty said you wouldn't probably feel any difference. But if you believe to build the engine often and want to properly weight balance each time you build, get a rod balancer would be a good idea.
    BTW, to run those cams, just make sure that you have Kiggly high pressure springs or Kelford springs.
     

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  13. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    Thanks for reminding him about the springs Hiroshi, nice catch. :thumb:
     

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    1990 Eagle Talon TSi AWD
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  14. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    So that you know, my motor in my car is the MW1 spec motor. It has a gram and a half spread across the 4 cylinders. I have hit the 8800 limiter a hand full of times and she seems to want to keep going a bit further. No odd vibrations or worries. Good springs and Kelford 264s with 9:1 Manleys and now on E!!! OMG :)
     

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    1992 Eagle Talon TSi AWD
    14.74 @ 117.04 · 1G DSM

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    1990 Mitsubishi Eclipse GSX
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    749  18

    1967 Chevrolet Camaro RS
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    fwd · manual · 2G DSM

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    1990 Eagle Talon TSi AWD
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  15. willyp42

    willyp42 Probationary Member

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    Thanks for looking out to my guys.
    I just have set of 8.3:1 weiscos with eagle rods and crank (2.0)
    Yes I have kiggly high pressures and evo rocker arms to match.
    I’ve never met anyone else run these cams, have you notice any rocker arm wear?
    That’s one of my major concerns.
    -Will
     
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  16. 1990TSIAWDTALON

    1990TSIAWDTALON Moderator

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    My son is running the high lift Kelfords and we haven't noticed any.....yet. I will keep an eye on it tho.
     

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    1992 Eagle Talon TSi AWD
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    1990 Mitsubishi Eclipse GSX
    awd · manual · 1G DSM

    749  18

    1967 Chevrolet Camaro RS
    rwd · automatic · Misc Vehicles

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    fwd · manual · 2G DSM

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    1990 Eagle Talon TSi AWD
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  17. DSMPT

    DSMPT Proven Member

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    I had run the 276HL for about 3 years. It was fine using the same rockers. I was shifting at 8800rpm.
     

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  18. willyp42

    willyp42 Probationary Member

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    That’s great to hear, Thanks everyone.
    Any turbo insight or recommendations?
    I have a gen 1 pte 6262 and going to see what she got.
     

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