what are the diameter differences? from the magic spreadsheet

http://www.ncs-stl.com/Files/BlowerRPM.xls

i get a stock of 2.93... is this right? if so, what is the HD...

thanks for the help

Ken

 

Our Lightning is 2.93 Stock, I know the HD is BIGGER but not sure what size it is, and I can't find any info on the internet for you.
I do know lots of HD guys look for our old Pulleys because is adds a couple of pounds to there stock Boost. Which means if our stock is 2.93 which it is, and a 2 Lb upper is 2.80 which it is, the difference is 0.13, so if thats the formular a stock HD should be around 3.06
HOPE THIS HELPS

 

Thanks, Rob... Basically, here is what I am trying to accomplish.

In looking at the spreadsheet link above, and knowing that a HD upper pulley nets 2lbs less, I am trying to ascertain the REAL boost level of a lower pulley relative to a lightning. In other words, everyone says a 6lb lower on the HD equals a 4lb lower on the L. I got the OD measurements of the stock pullies (from a guy at metco) of both trucks at 3.175 and 3.440 with .200 of a lip. that nets 2.975 and 3.240 where the pulley meets the belt which is a .265" difference.

Since the spreadsheet above lists 2.93, I added .265 to the number and got 3.195" for the Harley pulley....

So, plugging in a 9" lower (6lb pulley) and the 3.195 upper, you get a net just slightly above 3 pounds on a lightning...

Just trying to get the facts, Maam.

Ken

 

Ken
HD upper pulley diameter=3.82 from outside flange to flange
HD pulley diameter=3.38 inside the belt groove (roughly)
HD pulley diameter=3.4 across the top of the belt surface
Hope this helps you
Paul

 

Thanks, Paul...


Ken