4-cylinder boxer

The opposite engine is a piston internal combustion engine, in which the angle between the rows of cylinders is 180 degrees, and the opposing pistons move mirrors with respect to each other (at the same time reaches the upper dead point). It should be distinguished from the V-shaped engine with the collapse of the cylinders of 180 degrees, in which the pistons move synchronously (when one piston is in the upper dead point, opposing it in the bottom).