 With a Wright R-1820-4 Cyclone 770-horsepower (570-kilowatt) engine, it achieved a top speed of 254 mph (409 km/hr), with an estimated range of 1,000 miles at cruising speed.Some minor problems were found during testing and less than a year after its first flight, the aircraft was given a revised tail and rudder and a more powerful Wright R-1820-22 Cyclone 950-horsepower (710-kilowatt) engine, with which it reached a top speed of 263 mph (424 km/hr).At the time, it was believed to be the fastest single-engine bomber in the world.