To reduce the nitrogen oxides in exhaust gas by making exhaust pressure higher than the pressure in an intake manifold and minimizing fuel consumption in a diesel engine having a turbocharger with an exhaust gas recirculation device.

A secondary exhaust valve 20 is opened during expansion stroke and sometime after the completion of combustion stroke while the pressure in a combustion chamber 14 sometime still remains higher than the pressure in the intake manifold 36 by adding an EGR manifold 44 to the secondary exhaust valve 20. In order to allow the intake manifold 36 to receive highly pressurized exhaust gas from the EGR manifold 44, either EGR valve 50 or 53 or both of them can be opened. A valve 58 provided additionally between the EGR manifold 44 and an exhaust manifold damps the gas from the EGR manifold 44 to the exhaust manifold for releasing the compressed air in a cylinder before completing work for a piston.