The Wärtsilä RT-flex96C diesel engine has a bore diameter of 960 millimeters. Bore is the width of the cylinder measured across the inside, where the piston travels.
The RT-flex96C is a massive, low-speed, two-stroke marine diesel built for very large container ships. Its name’s “96” refers to the roughly 96-centimeter cylinder bore, while its stroke is an even longer 2,500 millimeters. That bore-and-stroke combination gives each cylinder an enormous displacement.
The engine uses electronically controlled common-rail fuel injection rather than the traditional camshaft-driven injection arrangement. The design entered commercial service in 2006, including propulsion of the Emma Mærsk container ship. Versions were built with six to fourteen cylinders, allowing total output to rise dramatically as cylinders were added. The bore is not the engine’s overall diameter or height; it is specifically the cylinder diameter.