Abstract: Provided is a gas engine wherein NOx concentration in exhaust gas can be maintained properly regardless of fuel gas composition. A gas engine (101) comprises a fuel gas supply regulation valve (45) for regulating fuel gas supply, an engine speed sensor (71) for detecting engine speed, an engine torque sensor (72) for detecting engine load, and a controller (50) for calculating a proper fuel gas supply and regulating the fuel gas supply regulation means to ensure the proper fuel gas supply thus calculated, wherein the controller (50), calculates the temperature difference of a combustion chamber in the combustion stroke of one combustion cycle by recognizing at least the engine speed and engine load and calculates the NOx concentration in exhaust gas based on the temperature difference, calculates a proper fuel gas supply based on the NOx concentration and regulates the fuel gas supply regulation valve (45) to ensure the proper fuel gas supply.

Abstract: A fuel feed device of a gas engine of non-supercheged type for feeding air and fuel to an intake port without mixing by amixer, wherein fuel gas is fed into the intake port by utilizing a negative pressure generated in the intake port in an intake stroke.

Abstract: A fuel feed device of a gas engine of non-supercheged type for feeding air and fuel to an intake port without mixing by amixer, wherein fuel gas is fed into the intake port by utilizing a negative pressure generated in the intake port in an intake stroke.