Abstract: A blowout preventer with a main body; a base releasably connected to the main body, the base having a base space therein, the base having a ram shaft opening; a primary piston movably disposed within the base space; a ram shaft to which the primary piston is connected, the ram shaft including a ram end and a piston end; a ram connected to the ram end of the ram shaft; a housing connected to the base, the housing having a housing space therein, the housing including a middle member with a member opening; a booster piston movably disposed within the housing space and having a booster shaft projecting therefrom and a booster shaft space therein; the shaft including a push portion selectively movable to abut the ram shaft to prevent movement of the ram shaft and to transfer force of the booster piston to the primary piston; and power fluid apparatus for the primary piston and the booster piston.