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Selecting Pulleys for your Powerdyne Supercharger
"What is the smallest pulley I can run on my BD-10, 11, 11a?"
A gear-driven supercharger (like the Vortec of Powerdyne XB1A) can run performance pulleys all the way down to our 2.25" pulley. But the belt-driven BD-series cannot.
How small of a pulley you can use on your BD-series on it depends on your shift point, whether you have an automatic or a manual transmission, and on the size of your crankshaft pulley.
Those BD (Belt Drive) series superchargers like to run the impellers at 36,000 RPM internally, and will accept intermittent peaks of 40,000 RPM. They have a 3-to-1 step-up ratio internally from the supercharger drive pulley to the driven (impeller) pulley.
EXAMPLE: A Powerdyne BD Supercharger is equipped with a 3" pulley and mounted on a motor that has a 6" crankshaft pulley. If that engine shows 6000 RPM on the tach, the supercharger drive pulley is spinning at twice that, or 12,000 RPM (because the 3" pulley turns 2x for each 1x of the 6"pulley). Within the Powerdyne, because the drive pulley is spinning at 12,000 RPM, the driven pulley (and the impeller attached to it) is spinning at 36,000 RPM.
Here is the equation: (see picture below)
(Engine Redline or Shift Point) x (Crankshaft Pulley Diameter "A") divided by (Supercharger pulley diameter "B") x 3 = Impeller Speed "D"
Plug the numbers in from your car and you'll know what is the smallest supercharger pulley you can run on your Powerdyne without sacrificing reliability.
Target 36,000 RPM at the Impeller if you want a long life from your Powerdyne and 40,000 RPM if you want more performance (and more frequent rebuilds).
We have supercharger pulleys in every size here!
Click to Enlarge
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