Six countries. The US, the UK, France, Russia, Ukraine and China. The most successful manufacturer in the world is Rolls‑Royce of the UK, and the manufacturer of the most high‑end jet engine in the world for fighter jets is Pratt & Whitney of the US.
GE is not as good as Pratt & Whitney in the high‑end engine market, but it is ranked second in both military and civilian markets, and it has Saffron, a joint venture with French Snecma, as its subsidiary. French Snecma seems to have great technology in both civilian and military markets.
Ukraine has the ability to design and manufacture jet engines for very large aircraft. Russia is particularly famous for its durability, although its turbine blade durability is inferior to that of the US and UK. I don't have much information on China. I know that it is a country where the people are very interested in jet engines.
Many dozens of countries can manufacture jet engines, keep in mind jet engines can be built with WWII era fabrication technology using materials that is not even the best available during the 1930s and 1940s. But those jet engines, while still functional jet engines, would be beneath absolute crap by contemporary standard of durability, efficiency, and reliability. If the goal is to manufacture technologically reasonably competitive military or civil engines, the list drastically shortens to just a handful.
Several countries license produce engines designed by others, and probably can build competitive engines of their own given additional investment. These might include Japan and India.
engines designed by others, and probably can build competitive engines of their own given additional investment. These might include Japan and India.
My friend, one of the build supervisors for the first Trent engines at the Rolls‑Royce factory at Ansty, used to put a half‑pence coin on the edge of one of the turbine blades and this micro weight was sufficient to turn the blades. “We didn’t build engines for Rolls‑Royce — we built them for us and they were the best in the world.”