Originally posted by redlightpete
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will a bobbed crank for 2.8l stroker balance out?
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89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...
new build thread http://www.r3vlimited.com/board/showthread.php?t=317505
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Originally posted by redlightpete View Post2. Is it a problem that the counterweights are smaller? No. It might be an issue in a vee configuration or a single, and then you might add "bob" weights to compensate.
You are confused. The bob weight is a calculated percentage of the weight of the rod and piston. The bob weight does not change to compensate for crank mods.
On a 90 degree V engine (single pin) a balance factor of 50% is typical. If the counterweight of the crank is not heavy enough to counter the required bob weight, holes will be drilled in the counterweight and heavy metal is inserted.
None of this applies to an inline 6 crank as previously mentioned.
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Originally posted by LJ851 View PostYou are confused. The bob weight is a calculated percentage of the weight of the rod and piston. The bob weight does not change to compensate for crank mods.
On a 90 degree V engine (single pin) a balance factor of 50% is typical. If the counterweight of the crank is not heavy enough to counter the required bob weight, holes will be drilled in the counterweight and heavy metal is inserted.
None of this applies to an inline 6 crank as previously mentioned.
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