This is a U.S.-built V-2 rocket engine made by the North American Aviation Company in 1947-1948 as part of their Navaho missile project. When North American started the project, it had no experience with rocket engines and built six V-2 engines to learn as much as possible about the construction of large-scale rocket engines. However, the engines were not fired in tests.
As Navaho expanded, North American developed a radically new and improved liquid propellant engine that was the start of the evolution of large-scale engines in the U.S. They included engines for the Redstone, Jupiter, Thor, and Atlas missiles and for the Saturn V Apollo launch vehicle and Space Shuttle. The U.S.-built V-2 engine was donated to the Smithsonian in 1970 by Rocketdyne.