Few questions about crankshafts

cml61386

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Jun 28, 2007
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Buffalo, NY
Has anyone heard of knife edging a crankshaft or bullnoseing a crank? I learned about this in school awhile ago and found this link that maybe helpfull. http://www.enginebuildermag.com/Article/1490/horsepower__building_in_and_bolting_on.aspx If you have never heard of this it is machine down the leading edge of the counter weight on the crank to lower resistance going throught the oil in the pan. Therefore you gain horespower because you cut down on resistance of the rotating mass. So I was wondering if anyone is running this in there current car and if anyone is running a dry sump oil system? To NASCAR fans that didn't know NASCAR runs both of those on all there Cup cars.
 

cml61386

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Jun 28, 2007
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Buffalo, NY
Finally I figured no one was gonna say anything. Dry sump oil systems ain't all that cheap either though. Thats nice but not a DD with that kind of setup.
 

cml61386

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Jun 28, 2007
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Buffalo, NY
Slow66;980301 said:
In the midst of setting up a dry-sump setup on my car now... still need a few things though.

Do you have any pictures of it? I imagine this is going to be strictly a drag car from what little I read from?
 

Rennat

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Dec 6, 2005
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If i recall correctly... you can only remove 8 or 9lbs from the 7m crank. (not the 6m) or you'll throw off the "natural" harmonics it was made with... IJ knows about this. Just wait for him to see the thread... so its worth very little for us. theres a lot of other areas that need attention.
 

suprarich

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Nov 9, 2005
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ohio
Our crank does not touch any oil in the pan. Cutting the counter weights reduces the surface area that oil may cling to, thus creating windage that puts drag on the crank.
 

Rennat

5psi...? haha
Dec 6, 2005
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more counter-weights which results in a smoother car. and some may argue that it also beats on the bearings less. but you take a 250RPM hit off of redline (which you'll never notice) its suppose to be a smoother running engine with one, which is exactly why i specifically found one. but the 6m will do just fine, either way though, get your engine balanced...
 

annoyingrob

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Jul 5, 2006
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Calgary, Alberta, Canada
just to clarify what Rennat said:

the 7M crank has more counterweights, which is why the 7M crank would be better than the 6M crank, not the other way around :)

cml asked why the 6M crank was better, and you told him why the 7M cank was better.