The Family II is a straight-4 piston engine that was originally developed by Opel in the 1970s, debuting in 1981. Available in a wide range of cubic capacities ranging from 1598 to 2405 cc, it simultaneously replaced the Opel CIH and Vauxhall Slant-4 engines, and was GM Europe's core mid-sized powerplant design for much of the 1980s, and provided the basis for the later Ecotec series of engines in the 1990s.

The Opel cam-in-head engine (CIH) is a family of automobile engines built by former General Motors subsidiary Opel from 1965 until 1998, appearing extensively in Opel/Vauxhall badged cars during this period. Both four- and six-cylinder inline configurations were produced. The name derives from the location of the camshaft, which was neither cam-in-block nor a true overhead camshaft. In the CIH engine the camshaft is located in the cylinder head but sits alongside the valves rather than above them, so therefore effectively is still an overhead valve design. The valves are actuated through very short tappets and rocker arms. The engine first appeared in the Opel Rekord B in 1965, and was largely replaced in four-cylinder form by the GM Family II unit as Opel/Vauxhall's core mid-size engine in the 1980s, with the six-cylinder versions continuing until 1994 in the Omega A and Senator B. A large capacity 2.4L four-cylinder version continued until 1998.