Pulley and crank pulley size


FBA

GT Owner
Dec 5, 2010
1,663
31.022340° N / 44.846191° W
Anyone know the alternator pulley and crank pulley size for the 6-rib? I assume when I did my Whipple 4.0 upgrade that didn't change the speed of the 6 rib? I heard the alt pulley is 59mm...
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,194
I've never heard of anyone doing that (on a GT).
 

FBA

GT Owner
Dec 5, 2010
1,663
31.022340° N / 44.846191° W
Doing what?
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,194
I had thought you were referring to the practice of undersizing pulleys. The SC belt drives the power steering pump and SC. More boost is achieved on the OEM or Whipple SC by changing the size of the pulley at the SC. (Smaller pulley = higher RPM = more boost).
 

GT101

*UK Support*
Supporting Vendor
Jan 20, 2010
381
Colchester, Essex, UK
As Kendall says - when you fit a Whipple (or just a smaller pulley on a stock blower) you don't change anything else apart from the belt to accommodate the new pulley. So everything else runs at the same speed it always did.
 

FBA

GT Owner
Dec 5, 2010
1,663
31.022340° N / 44.846191° W
I had thought you were referring to the practice of undersizing pulleys. The SC belt drives the power steering pump and SC. More boost is achieved on the OEM or Whipple SC by changing the size of the pulley at the SC. (Smaller pulley = higher RPM = more boost).
Oh...lol, no, they just oversized the alt pulley itself to avoid the thing grenading as it's done 4x in the past 8 weeks...and now I'm looking for another solution but need to get the stock crank and alt pulley size. My guess is that this OEM alt casing is junk and it's warping slightly under WOT, causing the internals to grenade...