Abstract: Systems and methods are disclosed for a two-part system with a gas generator and a driven engine system. In the two-part system, the first part of the system is the gas generator which produces power to operate and drive an engine. The driven engine is considered the second part of this two-part system. This method includes operating a gas generator combustion chamber that receives fuel, oxidizer, and water; an igniter coupled to the combustion chamber; and a computer controller that includes-sensors to sense pressure and temperature in the combustion chamber, wherein the computer controller controls the amount of fuel, oxidizer, and water in the chamber, and actuates the igniter. The combustion of the fuel and oxidizer combined with the steam that is produced are used to drive an engine. The system may also use an auxiliary unit to assist in the functions of the gas generator and the driven engine.