What is underdriving/underdrive?
Underdriving/underdrive is slowing the speed of the accessories, or the driven component, from their original factory speed. Underdriving can be done in two ways. First is by increasing the diameter of the accessory pulley/s. The problem with this method is it increases the size of the accessory pulley/s which increases their weight. Weight reduction is the most important key to increasing engine performance and response. This method also eliminates the ability to underdrive the a/c that robs alot of horsepower. The second, which we use, is reducing the diameter of the crank pulley. This allows us to achieve the best ratio of underdriving, and most importantly maximizes the reduction of weight on the crankshaft. This reduction in weight reduces the moment of inertia allowing your engine to respond faster to throttle inputs and perform better at all RPM’s. This method also allows underdriving of the a/c we can maximize the performance of our kits by not leaving any accessories to rob pr
