[MagnumForceGB]

Currently I have my supercharger off the car and the Pulley removed. After doing some math it looks like the pulley size is 3.8". Doing some math on the Vortech website with their V3 information and the a crank pulley size of 6" I came up with this (Boost Estimate is with a Ported Intake and 1-7/8" Tuned Length Headers (American Racing Headers):

Max RPM = 7300
Pulley size 3.8" = Impeller Speed: 41495. Estimated Boost: 9-10 (Confirmed)
Pulley size 3.6" = Impeller Speed: 43800. Estimated Boost: 10-11
Pulley size 3.48" = Impeller Speed: 45310. Estimated Boost: 11-12 (Tested 11-12 PSI)
Pulley size 3.40" = Impeller Speed: 46376. Estimated Boost: 12-13
Pulley size 3.33" = Impeller Speed: 47351. Estimated Boost: 13-14
Pulley size 3.25" = Impeller Speed: 48516. Estimated Boost: 14-15
Pulley size 3.125" = Impeller Speed: 50457. Estimated Boost: 15-16
Pulley size 3.00" = Impeller Speed: 52560. Estimated Boost: 16-17 (Non-Standard Vortech Pulley, Max Recommended)
Pulley size 2.87" = Impeller Speed: 54940. (Over speed)


The max impeller speed for the Vortech V3 SCi is 53000, so we are safe until 2.87" pulley.

How much of a boost gain should I expect from a 3.48" pulley? That will be 0.32" smaller. Car runs 18.5 degrees of timing with no knock retard on 90 degree days, so it should be able to handle just a hair more boost.