Early flight tests of the first General Electric turbojet engine, the Type I-A, clearly showed the need for more powerful engines. GE followed with two designs of increased thrust. The second, known as the J31, had 7,118 N (1,600 lb) of thrust and first ran in April 1943. About 250 were built, mainly for the Bell YP-59 and P-59A and B jet aircraft.
This engine was further developed for the U.S. Navy as a 100-octane, gasoline-burning version of the standard GE I-16 engine, which normally ran on kerosene fuel. This development was begun in 1943, when it was believed that future tactical needs would require turbojet engines to use the same fuel as reciprocating engines. Along with a Wright R-1820 piston engine, that version of the engine powered the Ryan FR-1, the Navy's first partially jet-powered aircraft.