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I think I'm going to miss the upcoming boating season.....
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Better to be aware of an issue now rather than when it is an obvious and costly problem. If it does cost some time for this season hopefully the pain won't be as bad as it could have been. Now is the time to get the engines right.
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Originally Posted by PQ290Enticer
(Post 4855584)
So to reach my goal of 500hp using the parts I bought, boring the cylinders was not required and because the bores were in good shape I was able to maintain the standard bore so just a hone. The guy said at my level, forged pistons weren't required. Forged are apparently also heavier(?) and again, just not necessary at my hp level. That was the story.
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Originally Posted by PQ290Enticer
(Post 4855584)
So to reach my goal of 500hp using the parts I bought, boring the cylinders was not required and because the bores were in good shape I was able to maintain the standard bore so just a hone. The guy said at my level, forged pistons weren't required. Forged are apparently also heavier(?) and again, just not necessary at my hp level. That was the story.
Obviously that could be anything typed in. What pistons do you actually have? Did you buy 4.250" or 4.280" pistons? |
Might as well go all the way in.
what were the engines originally? what cranks and rods are in them now? 454 mags had forged pistons in them stock so they downgraded them. |
The bore is still stock. I read 4.25. These were NOT the magnum engines so all cast stuff inside.
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I would have a hard time believing that you could take a standard bore block with some hours on it, hone it to clean up the cylinder walls and only have .002 clearance on new std bore pistons. It could happen, but I bet you have more piston to wall clearance than that.
I agree that forged pistons would be better, but I personally have a favorable opinion on KB pistons. I built many claimer engines back in the day for dirt track cars and used KB pistons in them. I never saw a piston failure that wasn't caused by something else, usually by a dropped valve or severe overheating. We ran these things hard, 7200+ rpm, lap after lap, night after night and sometimes got them very hot. I do know from experience that detonation or too small of a top ring gap will destroy them in very short order. I personally think that if you have enough piston to wall clearance, the top ring has a large enough gap and you don't have detonation, that the KB pistons will be just fine at 500hp. We made way more hp than that with them in small blocks. |
KB pistons are junk for marine use,maybe will last totally stock 330 HP engine ,cast I think are better in that case. Ask me why I know this ,fell for the argument over cast pistons once ,never again,also look at casting shift in KB pistons ,one skirt is almost twice as thick as other side,good old Mexican quality control.
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Originally Posted by snapmorgan
(Post 4855602)
I would have a hard time believing that you could take a standard bore block with some hours on it, hone it to clean up the cylinder walls and only have .002 clearance on new std bore pistons. It could happen, but I bet you have more piston to wall clearance than that.
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Originally Posted by PQ290Enticer
(Post 4855600)
The bore is still stock. I read 4.25. These were NOT the magnum engines so all cast stuff inside.
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