[tomasro]

Think about momentum: your flywheel may be the problem. they are meant for quick revving like in a slolom course, but for a drag you'll want a heavier flywheel. Lightened pulleys will also do the same thing, so you've got a double problem for a drag car.

Even though your engine is important in the drag, think about how you are using the energy too: lighten the load and stiffen the supension. It's all physics!