The PSA X engine is a family of internal combustion engines used in Citroën, Peugeot, Talbot and Renault automobiles. The X family was mainly used in superminis and the entry level models of midsize vehicles. It was designed and manufactured by the company "Française de Mécanique", a joint venture created by Peugeot and Renault in 1969, and built in Douvrin in northern France. It is commonly called the "Suitcase" engine, the "Douvrin" nickname being commonly used for the bigger 2.0-2.2 liter J-Type engine, which was also built in Douvrin.

The Douvrin family is an all-aluminum inline-four automobile engine designed in the early 1970s and produced from 1977 to 1996 by Compagnie Française de Mécanique, a joint-venture between PSA and Renault located in the town of Douvrin in northern France. This engine is designed by the engineer Jean-Jacques His. It was produced in the same factory as the PRV V6, which also is sometimes known outside France as the "Douvrin" V6. The Douvrin engine is also referred to as the ZDJ/ZEJ engine by Peugeot, and as the J-type engine by Renault.