The invention relates to an internal combustion engine system. The system includes a mixing unit comprising a four-way valve. The four-way valve having a first inlet connected to the EGR line, a second inlet connected to the air inlet line, a first outlet connected to the first intake manifold and a second outlet connected to the second intake manifold. The four-way valve is designed so that, in said normal operating mode, the intake gases supplied to the first intake manifold and to the second intake manifold have approximately the same proportion of exhaust gas and fresh air and so that, in said cylinder deactivation mode, the intake gas supplied to the first intake manifold only includes exhaust gas and the fresh air is directed exclusively to the second intake manifold.

The invention relates to an internal combustion engine system. The system includes a mixing unit comprising a four-way valve. The four-way valve having a first inlet connected to the EGR line, a second inlet connected to the air inlet line, a first outlet connected to the first intake manifold and a second outlet connected to the second intake manifold. The four-way valve is designed so that, in said normal operating mode, the intake gases supplied to the first intake manifold and to the second intake manifold have approximately the same proportion of exhaust gas and fresh air and so that, in said cylinder deactivation mode, the intake gas supplied to the first intake manifold only includes exhaust gas and the fresh air is directed exclusively to the second intake manifold.

A variable intake system includes a pair of surge tanks connected in a communicating manner to a main intake pipe through a low speed communication pipe and a high speed communication pipe, a middle speed communication pipe for connecting the pair of surge tanks, and a noise reducing member integrally provided at the middle speed communication pipe to reduce noise.