An apparatus and methods are provided for a throttle body spacer that improves the performance of an internal combustion engine. The throttle body spacer comprises a body that includes an airflow opening for conducting airflow from a throttle body into an intake manifold. A spiral is disposed along a sidewall of the airflow opening and configured for swirling the airflow. The spiral comprises a helical shape disposed around a circumference of the sidewall and extends from an initial bore near a first contact surface of the body to a second contact surface. The helical shape includes a diameter that increases as the spiral extends toward the second contact surface, giving the body a sidewall taper angle that contributes to an increase in power output of the engine. A sawtooth cross-sectional shape of the spiral causes the airflow to swirl so as to improve atomization of an air-fuel mixture entering engine.