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bore size

Discussion in 'Engine Building' started by Crix, Dec 24, 2004.

  1. Crix

    Crix Senior Member

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    Iam using a 94 B18b1 block with oversized pr3 (usdm) b16 pistons. What would the bore size be? 81.25?
     
  2. erebunicrx

    erebunicrx my name is Dale

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    usually they are 81.5. where did you buy the pistons? they sholud know.
     
  3. pissedoffsol

    pissedoffsol RETIRED

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    81 is std from honda
    81.5 is std overbore from honda
     
  4. Crix

    Crix Senior Member

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    whats the stock bore size of a ls? plus the .25 os pr3's? Do I just add? stock would be I think 81mm bore so 81.25? I just need to know so I can order the GE lsvtec conversion kit because its comes in differnt sizes. Basically my setup is a ls block with .25 os pr3's. Which kit would need to be ordered?
     
  5. brian11to1

    brian11to1 Senior Member

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    Yes stock bore of an LS is 81mm. so if you over bore it .25 its gonna be 81.25. good luck.
     
  6. pissedoffsol

    pissedoffsol RETIRED

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    81.25mm oem honda parts simply don't exist.

    allow myself to quote myself.

    81 = std bore oem
    81.5 = std overbore oem
     
  7. Crix

    Crix Senior Member

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    ok iam confused now, I bought .25 oversized pistons from honda dealer. I work there so I get good discounts. Honda doesn't sell .50 os pistons. They don't even reconmend going .30 over. I sent my block to engine lab and gave them my pistons and ls block. They fitted the pistons to factory tolerances. Which I would think would be 81.25mm bore if its a .25 over pistons. Ive already test fited on of the pistons and everything is well.

    What do you mean std. overbore is 81.5?
     
  8. Crix

    Crix Senior Member

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    you mean for that motor (ls) they don't come .25?
     
  9. nfn15037

    nfn15037 Senior Member

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    I think he left a "2" out of ".25". All OEM oversized pistons are .25 over.
     
  10. phunky.buddha

    phunky.buddha Admin with a big stick Admin VIP

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    81.25mm is the standard B18 oversize according to my Integra service manual. The allowable bore range is 81.25 to 81.27mm, with a maximum taper of 0.05mm between the top (6mm below deck) and bottom (6mm above bottom of sleeve).
     
  11. Crix

    Crix Senior Member

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  12. brian11to1

    brian11to1 Senior Member

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    so your bore should be 81.25
     
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