a device that injects hydrogen gas into an engine &# 39 ; s air intake or intake manifold that is demand controlled by the vehicle &# 39 ; s throttle linkage in an approximately linear manner . when the throttle is depressed , hydrogen generation can start or increase , and when the throttle is released , hydrogen generation can stop of decrease . the device of the present invention uses the vehicle &# 39 ; s own vacuum to control the production of hydrogen by forcing a liquid to rise in a chamber and into contact with metal in response to increasing vacuum thus producing an increasing amount of hydrogen gas with increasing throttle depression .