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Thread: Ring End Gap

  1. #1
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Ring End Gap

    Has anyone noticed the big difference in ring end gap specs offered by piston suppliers. I have been using Rivas old MTC supplied pistons and have just switched to CP.

    The MTC piston rings specified for boosted engines (bore x .0080") which results in an end gap around. 0031". But my new CP rings specify (bore x . 0055" for a boosted engine. Way smaller gap at around .0021".

    What is everyone running for ring end gap on their boosted (Turbo running 25+pounds) engines. How different can suppliers rings be to offer that much of a difference?


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    The most interesting man in the world. Nils888's Avatar
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    I would gap the rings a bit bigger than CP recommends. Also I would run the bore clearance .0045-0055

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    RXP 260 X Short Course Veteran RXP244's Avatar
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    Quote Originally Posted by Nils888 View Post
    I would gap the rings a bit bigger than CP recommends. Also I would run the bore clearance .0045-0055
    Hey Nils

    That was going to be my next question. CP piston to wall is . 0030" MTC was like .0032-.0037. The last pistons I ran before an unfortunate accident we set up with .0040 clearance. What am I missing? Are all these pistons and ring sets that different?

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    JPR's Avatar
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    MTC's, WSM and lightened OEM I aim for bore .0030-.0035. ( generally most Pistons are specific to each bore only) ....Ring gap will change depending on if it's stnd or hi comp Pistons and rec or race etc. tighter for rec loose for race. Bottom ring tighter then top that's on boosted to around 17psi and slight high comp,eg --- first ring 010 , second .080. this is my personal dealings only might I stress but everyone has a different method, I have just found this to work well for me

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    The most interesting man in the world. Nils888's Avatar
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    Quote Originally Posted by RXP244 View Post
    Quote Originally Posted by Nils888 View Post
    I would gap the rings a bit bigger than CP recommends. Also I would run the bore clearance .0045-0055
    Hey Nils

    That was going to be my next question. CP piston to wall is . 0030" MTC was like .0032-.0037. The last pistons I ran before an unfortunate accident we set up with .0040 clearance. What am I missing? Are all these pistons and ring sets that different?
    We have had a few cases of CP pistons in turbo seadoo's growing do to high temps in the combustion
    chambers.

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    steven mace's Avatar
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    WoW that's big gap. I built a blown Small block 383 chev and I ran 26 thou gaps on hastings rings and forged dished pistons 8.5:1 ratio.. and there 4" round..

  7. #7
    steven mace's Avatar
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    PS, the book gives you piston and ring clearances

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