Race Crank Balance

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perfconn
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Race Crank Balance

Post by perfconn » Fri Dec 07, 2018 3:57 pm

How close are racecranks normally balanced? 1% over/under-10% over-under?

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Re: Race Crank Balance

Post by Mark O'Neal » Fri Dec 07, 2018 4:19 pm

Normally? Depends on the opinion of the guy building it.

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Re: Race Crank Balance

Post by SchmidtMotorWorks » Fri Dec 07, 2018 7:27 pm

perfconn wrote:
Fri Dec 07, 2018 3:57 pm
How close are racecranks normally balanced? 1% over/under-10% over-under?
The pro teams order lot's of them at once (because of long lead time) in bob-weight steps of about 20 grams.
They rarely balance them beyond that.

Still never heard of a good reason for overbalance.
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Re: Race Crank Balance

Post by Mark O'Neal » Sat Dec 08, 2018 12:34 am

Because 99% of engine building is opinion.

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Dave Koehler
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Re: Race Crank Balance

Post by Dave Koehler » Sat Dec 08, 2018 7:12 am

more like best guess. :wink:
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Re: Race Crank Balance

Post by ijames » Sat Dec 08, 2018 9:15 am

SchmidtMotorWorks wrote:
Fri Dec 07, 2018 7:27 pm
perfconn wrote:
Fri Dec 07, 2018 3:57 pm
How close are racecranks normally balanced? 1% over/under-10% over-under?
The pro teams order lot's of them at once (because of long lead time) in bob-weight steps of about 20 grams.
They rarely balance them beyond that.

Still never heard of a good reason for overbalance.
Or, to put it as a %, if the bobweight is 1500 grams then 20/1500=0.0133 or 1.3% so they can get within +/- 0.67%.
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Re: Race Crank Balance

Post by Walter R. Malik » Sat Dec 08, 2018 9:21 pm

Mark O'Neal wrote:
Sat Dec 08, 2018 12:34 am
Because 99% of engine building is opinion.
But, in crankshaft engine balancing that opinion is normally based upon RPM range to be run;
not whether it is to be designated "Race" or not.
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Re: Race Crank Balance

Post by Mark O'Neal » Sat Dec 08, 2018 11:01 pm

Dave Koehler wrote:
Sat Dec 08, 2018 7:12 am
more like best guess. :wink:

People seldom defend a "best guess" to the death.

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Re: Race Crank Balance

Post by Dave Koehler » Sun Dec 09, 2018 6:53 am

There is that.
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