Piston pin fail, not a boat.
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Piston pin fail, not a boat.

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    Senior Member s2k1's Avatar
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    Default Piston pin fail, not a boat.

    With the recent pin talk I thought I would share an experience. Honda S2000 engine, 9000 rpm, 11:1 static, Garrett GT3540 with 28 psi boost on methanol. Too much you say???

    Made power and accelerated like I can't even begin to explain, for its size. Engine developed a "tick". Sounded like a loose valve. Checked the valves and they were perfect. I knew better than to keep running it so I tore it down and found this. The pin said uncle and thankfully I listened.





    Hard to see in my amateur pics but in the last photo the ID of the pin boss on the right side of the piston is self destructing where the crack in the pin was located. Needless to say, I am extremely lucky it didn't come apart and saw the engine up into a bunch of pieces.
    Original pin is .904" x .196" taper wall. Have new CP straight wall DLC pins for it now, haven't put it back together yet.
    Chris @ Benchmark Performance

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    gn7
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    I am going to go on record here and take the beating for it later. So let me say straight up right now before it comes. Screw you all!

    First, you are one very lucky SOB! If that was me, the motor would be laying in two.

    Now, .....tapered pins are the dumbest thing ever installed in a motor. Specially if you have no intentions of tearing it down every other race. Does the load some how deminish as it gets further from the center? Is it because its in the piston hole and some how supported. Does anybody have some structural load engineering to prove this out? Because I have time and would love to read it. The biggest issue with piston pins isn't the bending. Its that when they bend, they go oval. And bye bye clearence. Then the pin gets hot. Galls the piston. Galls the rod end. Then it seizes.

    But this didn't have to be pin flex. Although I think it is. But it could just as easily be heat through the piston, (that turbo curse) and lack of lube. Keep this in mind. the DLC was a smart move. In a roller motor, this is where I go to see if my oil is doing its job. If I was running a vacuum pump or dry sump, I would look here before I looked at the valve stems.

    What material are the new pins?

    Again, you are sooooo very lucky!



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    Last edited by gn7; 07-13-2010 at 08:07 PM.

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    cfm
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    Quote Originally Posted by s2k1 View Post
    Engine developed a "tick". Sounded like a loose valve. Checked the valves and they were perfect. I knew better than to keep running it so I tore it down and found this. The pin said uncle and thankfully I listened.
    Smart man ! Wish I was that smart the last million of times I broke something.

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    Senior Member s2k1's Avatar
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    Quote Originally Posted by gn7 View Post
    What material are the new pins?
    New pins are 9310. Old pins are OE Honda S2000 parts, as are the pistons, rods, and crank.
    Engine is factory equipped with piston squirters. No heat in the bottom of the piston crowns.
    Chris @ Benchmark Performance

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    gn7
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    Quote Originally Posted by s2k1 View Post
    New pins are 9310. Old pins are OE Honda S2000 parts, as are the pistons, rods, and crank.
    Engine is factory equipped with piston squirters. No heat in the bottom of the piston crowns.
    Oh yeah, your ready to rock now Now you just have to hope you don't fold a rod or shoot the crank out the bottom



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    Senior Member s2k1's Avatar
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    With about 5 years of duning in the sand car in my avatar, and this being the only significant problem, i'm feeling pretty lucky!

    Sand car is long gone, motor may go into a drag car now. We'll see, it doesn't have a home for now. But with the way that it ran, i'll definitely find something to do with it!
    Might make an eye opening small boat engine!
    Chris @ Benchmark Performance

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    Senior Member Hass828's Avatar
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    Quote Originally Posted by s2k1 View Post
    With the recent pin talk I thought I would share an experience. Honda S2000 engine, 9000 rpm, 11:1 static, Garrett GT3540 with 28 psi boost on methanol. Too much you say???

    Made power and accelerated like I can't even begin to explain, for its size. Engine developed a "tick". Sounded like a loose valve. Checked the valves and they were perfect. I knew better than to keep running it so I tore it down and found this. The pin said uncle and thankfully I listened.



    Hard to see in my amateur pics but in the last photo the ID of the pin boss on the right side of the piston is self destructing where the crack in the pin was located. Needless to say, I am extremely lucky it didn't come apart and saw the engine up into a bunch of pieces.
    Original pin is .904" x .196" taper wall. Have new CP straight wall DLC pins for it now, haven't put it back together yet.
    I'll bet it did
    Very lucky, wish mine would have gave a little warning.
    that thing sounds like alot of fun.
    "if we keep doing it the same way we always do..we will always get the same results"
    H8-2-W8
    [email protected] first pass

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