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Underdrive Pulleys

Back in the late 1980’s when our team was figuring out the best ways to get more horsepower out of Detroit’s latest breed of electronic fuel injected models, our engineers started playing with the speed of the serpentine belt system. Unlike earlier carbureted vehicles that used separate belts for many of the accessories, these latest vehicles all came standard with a single serpentine belt that ran all accessories.

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In extensive dyno testing & drag racing, our engineers were able to pinpoint large horsepower losses from the drag created by these accessories. By decreasing the size of the crankshaft pulley which turned the accessories it was found that significant performance enhancements could be gained. Increasing the size of the alternator & water pump pulleys further slowed these two items and further increased performance in addition to allowing the stock serpentine belt to work with the three new pulleys. Through much testing perfect sizing was found that would allow for more than enough water flow and charging current while freeing up 10-15 horsepower on a typical application. Fast forward to today and our “Power Plus Series” performance underdrive pulley systems have become one of the top bolt-on products for many automotive & truck applications.

All BBK performance underdrive pulleys begin life as billet 356 aluminum alloy which is precision CNC machined for maximum performance and a perfect fit. Most kits include a new crankshaft, water pump and alternator pulley and are a direct bolt on designed for either street or track use. Mustang, systems are now produced for many Ford, Dodge & GM auto and truck models.

Installation is straight forward and seat of the pants performance gains are second to none for such an affordable power adder. While our first underdrive pulley kit was designed for the original 5.0L

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