Notices
Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by: KPower

Crank lightening, not knife edging

Thread Tools
 
Search this Thread
 
Old Apr 21, 2010 | 04:47 PM
  #1  
thesnowboarder's Avatar
Thread Starter
Elite Member
iTrader: (15)
 
Joined: Sep 2007
Posts: 2,034
Total Cats: 5
From: Incline Village, NV
Default Crank lightening, not knife edging

Name:  -2-2.jpg
Views: 949
Size:  47.2 KB

discuss.
Old Apr 21, 2010 | 04:57 PM
  #2  
TURNS101's Avatar
Senior Member
iTrader: (10)
 
Joined: Oct 2005
Posts: 715
Total Cats: 5
Default

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 :(
Old Apr 21, 2010 | 04:57 PM
  #3  
aznDragonX's Avatar
Junior Member
iTrader: (5)
 
Joined: May 2006
Posts: 351
Total Cats: -1
From: San Francisco Bay area
Default

I know I am next !
Old Apr 21, 2010 | 04:58 PM
  #4  
aznDragonX's Avatar
Junior Member
iTrader: (5)
 
Joined: May 2006
Posts: 351
Total Cats: -1
From: San Francisco Bay area
Default

Originally Posted by TURNS101
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?
Old Apr 21, 2010 | 07:03 PM
  #5  
johnmatt's Avatar
Senior Member
iTrader: (8)
 
Joined: Feb 2009
Posts: 896
Total Cats: 0
From: Jax, Fl
Default

This isn't as expensive as knife edgeing is it? I'd like to get it done if it doesn't cost $600
Old Apr 21, 2010 | 08:01 PM
  #6  
TurboTim's Avatar
Elite Member
iTrader: (9)
 
Joined: Jun 2006
Posts: 7,033
Total Cats: 425
From: Chesterfield, NJ
Default

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.
Old Apr 21, 2010 | 08:06 PM
  #7  
aznDragonX's Avatar
Junior Member
iTrader: (5)
 
Joined: May 2006
Posts: 351
Total Cats: -1
From: San Francisco Bay area
Default

it's like lighten flywheel that make the car rev up faster..
Old Apr 21, 2010 | 08:13 PM
  #8  
mazpr's Avatar
Senior Member
iTrader: (1)
 
Joined: Oct 2008
Posts: 531
Total Cats: -19
From: Trailer County
Default

Unless there is a see side by side dyno comparison sheets, it seems a waste of money.
Old Apr 21, 2010 | 08:36 PM
  #9  
Dlaitini's Avatar
Junior Member
 
Joined: Aug 2006
Posts: 239
Total Cats: 5
From: Cedar City, UT
Default

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
Old Apr 21, 2010 | 08:48 PM
  #10  
curly's Avatar
Cpt. Slow
iTrader: (25)
 
Joined: Oct 2005
Posts: 15,168
Total Cats: 1,393
From: Oregon City, OR
Default

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?
Old Apr 21, 2010 | 09:25 PM
  #11  
JasonC SBB's Avatar
Elite Member
 
Joined: Jul 2005
Posts: 6,420
Total Cats: 84
Default

Is the lightest flywheel in the market not light enough?
Old Apr 22, 2010 | 08:29 AM
  #12  
miata2fast's Avatar
Elite Member
iTrader: (2)
 
Joined: Aug 2009
Posts: 3,145
Total Cats: 175
From: Dover, FL
Default

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.
Old Apr 22, 2010 | 09:41 AM
  #13  
Sparetire's Avatar
Elite Member
 
Joined: Dec 2008
Posts: 1,642
Total Cats: 36
From: Colorado
Default

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.
Old Apr 22, 2010 | 10:52 AM
  #14  
johnmatt's Avatar
Senior Member
iTrader: (8)
 
Joined: Feb 2009
Posts: 896
Total Cats: 0
From: Jax, Fl
Default

$300 is a good price for a knife edge. I called a place about it and it was gonna run me around $900.
Old Apr 22, 2010 | 12:57 PM
  #15  
miata2fast's Avatar
Elite Member
iTrader: (2)
 
Joined: Aug 2009
Posts: 3,145
Total Cats: 175
From: Dover, FL
Default

Originally Posted by johnmatt
$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.
Old Apr 23, 2010 | 01:52 AM
  #16  
JasonC SBB's Avatar
Elite Member
 
Joined: Jul 2005
Posts: 6,420
Total Cats: 84
Default

Originally Posted by miata2fast
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?
Old Apr 23, 2010 | 03:14 AM
  #17  
dc2696's Avatar
Senior Member
iTrader: (2)
 
Joined: May 2005
Posts: 1,202
Total Cats: 21
From: Edmonton Ab, Canada
Default

Mine was lightend(not knife edged), worked well till the OP exploded making it a boat anchor.
Old Apr 23, 2010 | 04:25 AM
  #18  
turotufas's Avatar
Elite Member
iTrader: (7)
 
Joined: Jul 2009
Posts: 3,304
Total Cats: 7
From: Gainesville,Fl
Default

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.
Old Apr 23, 2010 | 11:30 AM
  #19  
Stealth97's Avatar
Elite Member
iTrader: (5)
 
Joined: Oct 2007
Posts: 2,156
Total Cats: 67
From: Canton, Ga
Default

Just get the cast SOHC protege crank, its like 10 or 11lbs lighter
Old Apr 23, 2010 | 12:55 PM
  #20  
southernmx5's Avatar
Junior Member
iTrader: (1)
 
Joined: May 2009
Posts: 328
Total Cats: 4
From: TN
Default

Originally Posted by turotufas
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.



All times are GMT -4. The time now is 03:04 AM.