EMPI VW Crank Power Pulley - 5 Hole Design - Black Numbers

Replace your stock diameter crank pulley with this Power Pulley from EMPI. This aluminum 5-hole design pulley is smaller than the original crank pulley and has black timing marks. On a stock set up, the crank pulley is larger than the generator pulley, so the fans spins more than once for every rotation of the crank. A smaller diameter crank pulley (or power pulley as it is sometimes known) changes the ratio between the two, effectively reducing fan RPM relative to engine rotation speed. This minimizes the load coming from the generator fan and frees up engine horsepower to be used to move the car. Installing a power pulley will reduce engine cooling and charging by the generator. This power pulley fits on all 12 volt Type 1 VW motors, including 1967 to 1977 Standard Beetle, 1971 to 1979 Super Beetle, 1967 to 1974 Karmann Ghia, and 1967 to 1971 Bus.

The outer diameter of this pulley is roughly 5 13/16"/148mm. Coupled with a standard upper pulley with an outer diameter of 4.25"/108mm the pulley ratio would be approximately 1 to 1.37, meaning the fan will turn 1.37 times every time the cranks makes one full revolution which is less than the factory ratio of 1.69. This means the pulley won't cool as effectively as the stock unit but does use less power to turn the fan which frees up horsepower.