Impeller speeds with cog setup

does any one know the formula for finding impeller speed with a cog pullies

or what cog set up it would take to spin a novi 2000R to max impeller speed @7200rpm

thanks

There's a spreadsheet avail for download here:
http://www.superchargerhelp.com/showthread.php?t=4907

Change the step-up ratio to match your blower and then to the far right you can input over the existing data for Cog pulley sizes.

73/33 would be pretty close if you wanted 55k impeller