Power Up: Getting The Right Pulley For Your High Output Alternator

Having an alternator on any high-performance street car is a requirement, and for a racecar it will help extend time away from the pits being chained to a battery charger. There is more to making an alternator work with an electrical system than bolting it on, wiring it up, and routing the belt, it has to have a pulley to match the output required. Adding a power pulley that isn’t sized correctly could lead to improper charging and the failure of your expensive high-output alternator.

In most situations buying a direct replacement alternator is just a matter of knowing how many amps the new one needs to be, but with high-performance applications, the game is slightly different. Since a performance alternator has a different power curve, a power pulley is used to get the most out of the unit. Where the trouble can begin is when the pulley ratio isn’t correct and will affect the alternator’s performance at high and low speeds.

An alternators function is based on the speed it rotates and that output is measured on a curve.  Based on this, the pulley ratio you use is critical to make sure the alternator functions correctly at all times. With companies like Powermaster, their alternators come with a pulley that is specifically matched to the alternator’s curve and amount of winds on the motor. For street cars Powermaster recommends a 3:1 ratio and for drag racing applications an overdrive ratio of 1.75:1 should be used to assist with charging between runs.

To learn more about how to pick the best alternator and pulley for your car make sure to check out the Powermaster website right here.

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Brian Wagner

Spending his childhood at different race tracks around Ohio with his family’s 1967 Nova, Brian developed a true love for drag racing. Brian enjoys anything loud, fast, and fun.
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