... not clear on how the belt tensioner works on your setup and how 85-100 Foot Pounds is being measured, I'd like to know - pics may help'.
I had belt derail problems after switching to very small driven pulley (2.5") on a V2 SC / 250. The
idler roller alignment was critical to keep belt on and at higher RPM's/boost, the Vortech was getting pulled in slightly on mounting plate by the increasing belt tension. Critical alignment of the Idler and an additional support from for Vortech mounting plate has kept it spinning' ... (steel rod - triangled' to V2's front from bellhouse )
have fun
250 Cubic Inch Displacement Straight Six with Vortech V2 Centrifugal Supercharger and Holley 2300 350 CFM 7448 2Bbl heavily modified for Blow-Through boost levels. Extensive Fuel supply, Ignition and Drivetrain mods to handle increased power under boost. Boost levels monitored at Supercharger, Carb and Intake Manifold, with real-time Air Fuel Ratio monitoring. Previous forced induction 250 attempts yielded piston ring lands blown off as boost neared 20 PSI. Currently limiting Boost to @ 6-10 PSI pending further engine mods.
Vortech V2 specs are @ 680 HP at 20PSI boost at 50,000RPM Impeller speed.
With serpentine 6.125” (5.0 SBF) Crank Pulley and 2.5” Supercharger pulley, the two pulley sizes and internal SC step-up gearing yields an IMPELLER rotation speed calculated at @ 22,000 RPM at cruise speed with engine RPM @ 2500RPM.
At typical 250 SIX upper shift point of @ 5,000 RPM the Supercharger impeller speed approaches 45,000 RPM !. Calculating to an Impeller speed @ 750 Revolutions per SECOND.