Belt size for Whipple Supercharger

[02lightning14]

I just purchased a Whipple supercharger for my 02 Lightning. I have a stock lower with stock size idle pulleys. The blower pulley is 3.25. What size belt do I need?

 

[Dusten]

Its likely going to be a 68.5" belt

 

[02lightning14]

Thanks for the info,Dusten