In the accessory drive system, the crankshaft drives the water pump, alternator, power steering pump, A/C compressor and other accessories via an arrangement of pulleys mounted to each component and one or more drive belts. While the amount varies according to vehicle, all accessories use up horsepower – power that could be applied to your drive wheels. But there are ways to reduce your accessories’ power consumption without negatively affecting function.
You can gain horsepower by reducing the weight of your pulleys and by changing their diameter. We offer aluminum pulleys that are much lighter than the original equipment pulleys, without any reduction in strength. These pulleys are direct replacements and require no modifications for installation. Their light weight not only results in a horsepower increase, but the reduced rotational mass also improves throttle response.
Reducing the diameter of the crankshaft drive pulley or increasing the diameter of the driven accessory pulley underdrives the accessory, slowing its rotational speed and reducing the amount of horsepower it draws. However, the size of the pulleys must be carefully calculated so your accessories continue to operate properly. Everyone wants more horsepower, but not with adverse side effects like reduced power steering assist, an alternator that doesn’t charge the battery, or an overheated engine. Our pulley kits have been extensively tested to deliver maximum horsepower with no loss of accessory functionality.
Using underdrive pulleys to reduce accessory drag is an easy and inexpensive way to gain as much as 15 horsepower! Each kit is engineered for the specific application, ensuring straightforward installation. Most kits are designed to use the existing serpentine belt, but a belt is supplied if a different length is required. Most lightweight and underdrive pulleys are machined from high grade aluminum alloy, some with an attractive chrome or anodized finish, so if not for the horsepower increase, you’ll want them just for an engine appearance upgrade.