Abstract: In an internal combustion engine with two or more cylinders and two inlet valves per cylinder, in which the intake passages of two adjacent cylinders, which lead towards the inlet valves, are located side by side, symmetrically relative to the symmetry plane of the two cylinders, and in which the cylinder head is made in one piece and has one common inlet flange with an inlet channel, which is flow-connected, past a lug receiving one of the cylinder head studs, with the intake passages formed by guiding surfaces and leading towards the individual inlet valves, the intake passages leading to the inlet valves positioned at a lesser distance in the direction of flow are guided on one side of the lug and the intake passages leading to the inlet valves positioned at a greater distance are guided on the other side of the lug, and the inlet valves of the adjacent cylinders are controlled in such a way that the cylinders are fed with combustion air at different points in time.

Abstract: In order to observe and optically record the processes in the combustion chamber of an internal combustion engine during operation, at least one observation bore located in the wall of the combustion chamber is provided with a transparent window as well as an image pickup device, e.g. an endoscope, which may be inserted as far as to this window and is connected to an image recording unit by way of an image transmission device. In order to prevent the premature build-up of sooty deposits the window may be separated from the adjacent, cooled parts of the wall of the combustion chamber by a gap which will reduce the dissipation of heat.

Abstract: Apparatus for working of aligned bores, particularly for repairing of crank shaft bearings and their bores of internal combustion engines. In the region of the bore to be worked on there is provided a driven hollow shaft carrying a tool for working the bore or bores, which hollow shaft is adjusted relative to a laser beam which is in alignment with the longitudinal axis of the bores.