sentences:  Only three more prototypes were completed.In an attempt to salvage the project, two additional airframes were fitted with 1,530 hp Mitsubishi MK4B 12 "Kasei" engines and redesignated G5N2s.Although the Mitsubishi engines were more reliable than the original Mamori 11s, the aircraft was now even more hopelessly underpowered and further development of the type was halted.