Lycoming GSO-480-B2D6

O-480
Type	Piston aero-engine
Manufacturer	Lycoming Engines
First run	1954
Major applications	Beechcraft Twin Bonanza Beechcraft Queen Air Dornier Do 27

The Lycoming O-480 is a family of six-cylinder, horizontally opposed fixed-wing aircraft engines of 479.6 cubic inch (7.86 l) displacement, made by Lycoming Engines. The engine is a six-cylinder version of the four-cylinder Lycoming O-320.

O-480 series engines are installed on a number of different aircraft types. Their main competitive engines are the Continental IO-520 and IO-550 series.

All engines have an additional prefix preceding the 480 to indicate the specific configuration of the engine. Although the series is known as the "O-480", they're are the only geared engines in the series. There are also numerous engine suffixes, denoting different accessories such as different manufacturers' carburetors, or different magnetos.

Data from FAA Type Certificate.

...
Wikipedia