Ok so I wanted to post a little more info.....Since i have been getting a lot of questions about this with my group purchase coming up on the LG0 sized crank and over driven alternator pulley for the LD9. "The alternator pulley will fit all 95-05 j-bodies."
A stock crank pulley working diameter is 6.406".
A stock alternator pulley working diameter is 2.208".
My over driven ld9 crank pulley working diameter is 7.000"
My LG0 crank pulley working diameter is 5.180"
My over driven alternator pulley working diameter is 1.818"
Some easy calculation time.
So lets say red line is 6,500 RPM, stock crank and alternator pulley.
With a stock crank pulley rotating at 6,500 rpm, the alternator pulley would be rotating at 18,858 RPM.
Example. 6500 rpm x 6.406" = 41639 / 2.208" = 18,858.243 RPM.
So lets say red line is 6,500 RPM, LG0 sized crank and my over driven alternator pulley.
With a LG0 crank pulley rotating at 6,500 rpm, the alternator pulley would be rotating at 18,520 RPM.
Example. 6500 rpm x 5.180" = 33670 / 1.818" = 18,520.352 RPM.
So lets say red line is 6,500 RPM, over driven crank and my over driven alternator pulley.
With a over driven crank pulley rotating at 6,500 rpm, the alternator pulley would be rotating at 25,027 RPM.
Example. 6500 rpm x 7.000" = 45500 / 1.818" = 25,027.503 RPM.
So lets say red line is 6,500 RPM, LG0 crank and stock diameter alternator pulley.
With a LG0 crank pulley rotating at 6,500 rpm, the alternator pulley would be rotating at 15,249 RPM.
Example. 6500 rpm x 5.180" = 33670 / 2.208" = 15,249.094 RPM.
Please someone check my numbers.
The Supercharger formula that was posted....which is the same thing as mine, but organized different.
Top from boost forum & Bottom is my formula.
Crank Pulley diameter 6.406" / Supercharger pulley size 2.7" = 2.373 X engine Red line 6,500 = 15421.852 RPM
Red line 6500 x crank pulley diameter 6.406" = 41639 / super charger pulley size 2.7" = 15421.852 RPM
Edited 1 time(s). Last edited Thursday, May 03, 2012 7:55 AM
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO