The Harley-Davidson engine family that debuted in 1999 with the 88-cubic-inch Twin Cam 88 was the Twin Cam family.
Harley-Davidson developed the Twin Cam as the successor to the Evolution engine for many large motorcycles. Its name came from the two camshafts used in the engine’s lower-end design, a change from the Evolution’s single-cam arrangement.
The first widely known version was the Twin Cam 88, whose 88-cubic-inch displacement equaled about 1,450 cubic centimeters. Harley-Davidson later produced larger versions, including the Twin Cam 96 and Twin Cam 103.
The Twin Cam is sometimes confused with Milwaukee-Eight because both are large Harley-Davidson V-twin families. Milwaukee-Eight arrived later, in 2016, and became the successor to the Twin Cam in many touring and cruiser applications.