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Spockie-Tech
Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
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Thats a bit simplistic, because the piston/conrod assembly is mostly reciprocating at the piston end), and partly rotating and reciprocating at the big-end.
A race engine building shop I know has a set of scales with a mount point that holds the little end of the conrod up, and weighs the big-end.
Then they plug those numbers into a formula that takes into account the length of the conrod (distance between big and little end centers), and gives them a precentage of the overall weight that they bolt to the crank-pin using special jigs that have the weights mounted around the pin in a particular configuration to simulate the offset weight of the conrod.
Then they spin this up on an electronic balancing machine to various RPM's, the machine measures the vibrations and angles, and tells them where and how much to drill out of the counterweights.
Sometimes, if there have been radical changes made to the factory balance (aluminium conrods, or a super light piston), then they need to cross drill the crank and insert plugs of heavy-metal to actually add weight in some cases and re test several times to get it spot on.
If you're trying to "blueprint" the engine and up its power or rpm's significantly, its probably best left to a pro with the gear to do this sort of job.
Have you changed anything that would require significant rebalancing ? _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
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Wed Sep 19, 2007 10:46 am |
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