The power of a spark ignited engine is directly related to the mass of air flowing into the cylinders. A conventional throttle (refer to Figure 1) regulates the air flow into the engine by imparting a non-recoverable pressure loss upstream of the engine. The throttle plate operates by suffocating the engine’s airflow; the throttled engine cannot breathe, and therefore delivers less power. The work required to overcome the vacuum created by throttle plate wastes fuel and reduces the engine efficiency. Consequently, throttle plates are highly effective -- but highly inefficient -- throttling devices.
To overcome the inefficiency of the throttle plate, a variable area Venturi has been developed, patented, designed, and tested. The resulting design is a Venturi induction system, whereby the Venturi area is varied by an axial moving pintle. Engine throttling is accomplished by changing the area of the Venturi rather than imparting an unrecoverable pressure loss.