Speedway Cast Aluminum double groove pulleys for Small Block Chevy feature a 20% reduction. Reduction pulleys have a smaller diameter which slows the speed of your fan, water pump, and alternator to reduce drag for more top-end horsepower. Plus, high RPM water pump operation is improved due to reduced fluid cavitation.
This is a 25% reduction pulley when used with the correct upper pulley, part number 91015476.
- Machined from lightweight cast aluminum
- Superior belt retention with extra-deep grooves
- 20% reduction slows accessories down for less drag
- Adds top-end horsepower
- Reduces water pump impeller speed below cavitation threshold
- Improved high-RPM cooling capabilities
- 910-15488
Available for long water pumps. 5/8" shaft.
Note: The lower crank pulleys are manufactured thicker than normal stock pulleys. This requires longer 3/8" bolts to be purchased separately. Allen head type bolts recommended.