protests from curtiss led to the formal flyoff between the fighters to be delayed until april 1936. the delay was used by both seversky and curtiss to improve their aircraft, while allowing additional fighters from vought (the vought v-141) and consolidated with a single seat version of the pb-2. the sev-1xp was re-engined again, with a two-row pratt & whitney r-1830-9 "twin wasp" replacing the cyclone and a modified vertical stabilizer fitted, becoming the sev-7.