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Old 04-21-2010, 05:47 PM   #1
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Default Crank lightening, not knife edging

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Old 04-21-2010, 05:57 PM   #2
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I did it. Took off 7lbs. I thought it was really cool. Looked really cool. Just found out its 1 more thing that slows your turbo from spooling :(
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Old 04-21-2010, 05:57 PM   #3
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I know I am next !
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Old 04-21-2010, 05:58 PM   #4
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Quote:
Originally Posted by TURNS101 View Post
I did it. Took off 7lbs. I thought it was really cool. Looked really cool. Just found out its 1 more thing that slows your turbo from spooling :(
Did you gain low end tq by lighten the crank?
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Old 04-21-2010, 08:03 PM   #5
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This isn't as expensive as knife edgeing is it? I'd like to get it done if it doesn't cost $600
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Old 04-21-2010, 09:01 PM   #6
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Looks cool to me. I'm not sure why it'd slow spool, other than the engine reving quicker than the turbo can keep up.
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Old 04-21-2010, 09:06 PM   #7
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it's like lighten flywheel that make the car rev up faster..
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Old 04-21-2010, 09:13 PM   #8
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Unless there is a see side by side dyno comparison sheets, it seems a waste of money.
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Old 04-21-2010, 09:36 PM   #9
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idk, i would think any weight removed that would rob power from accel/decel the rotateing assy up to speed would then be able to be trasfered to the wheels instead... now $ per power gained... thats another story
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Old 04-21-2010, 09:48 PM   #10
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What all did you do to lighten it? I see the holes going towards the center of the connecting rod races, that's not stock, is it? Were the counter weights modified at all?
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Old 04-21-2010, 10:25 PM   #11
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Is the lightest flywheel in the market not light enough?
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Old 04-22-2010, 09:29 AM   #12
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I recently got a quote from Robello Racing to knife edge the crank, it was around $300.00. He thought that since I was drag racing it was not really a good idea. He recommended I do mild crank lightening instead.
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Old 04-22-2010, 10:41 AM   #13
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Is that from jackstranmissions.com?

It works pretty well in some apps. From what I can see the counter weights are for rotational weight and driveability rather than engine longevity. It might loose spool, but it will also free up some power in the first few gears where the RPMs change quickly in any sort of meaningful acceleration.
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Old 04-22-2010, 11:52 AM   #14
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$300 is a good price for a knife edge. I called a place about it and it was gonna run me around $900.
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Old 04-22-2010, 01:57 PM   #15
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Quote:
Originally Posted by johnmatt View Post
$300 is a good price for a knife edge. I called a place about it and it was gonna run me around $900.
I do not know to what extent they would be doing on the knife edge for that $300.00 price, but Robello is a very reputable engine builder.
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Old 04-23-2010, 02:52 AM   #16
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Quote:
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I recently got a quote from Robello Racing to knife edge the crank, it was around $300.00. He thought that since I was drag racing it was not really a good idea. He recommended I do mild crank lightening instead.
Rebello in Northern CA?
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Old 04-23-2010, 04:14 AM   #17
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Mine was lightend(not knife edged), worked well till the OP exploded making it a boat anchor.
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Old 04-23-2010, 05:25 AM   #18
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Someone told me never to knife edge a crank. Can't remember why or who told me that though. Anyways, lightening might be good to relieve some stress off of internal pieces too.
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Old 04-23-2010, 12:30 PM   #19
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Just get the cast SOHC protege crank, its like 10 or 11lbs lighter
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Old 04-23-2010, 01:55 PM   #20
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Quote:
Originally Posted by turotufas View Post
Someone told me never to knife edge a crank. Can't remember why or who told me that though. Anyways, lightening might be good to relieve some stress off of internal pieces too.
Knifing the crank without balancing the entire rotating assembly can cause excessive vibration at high rpm. If you want to remove any weight from the crank you might as well send it to an engine builder for balancing.
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