Source: ACPT.com
In some applications, the side effects of an ultra-light flywheel negate the benefits. For example, drag-racing vehicles depend on a near-stock-weight or heavier flywheel to store the necessary amount of energy for an explosive launch. Since the launch is the most critical aspect of a drag race, most racers can’t afford to give up launch quality by using a lightened flywheel to pick up a slight improvement in acceleration. Of course, other forms of racing, which are less dependent on acceleration from a dead stop, can benefit from the use of lightweight flywheel setups.