On September 1st 1931, Lowell Bayles raced over the Shell qualifying course in the Gee Bee "Z" setting an unofficial speed record of 267 mph, and later in the week won the Thompson Trophy. In November of 1931, the Gee Bee "Z" was refitted with a new and more powerful Pratt & Whitney Wasp Sr. engine. It was capable of 314 mph. That same month Bayles made three attempts to break the world's speed record. On his first two attempts, Bayles failed to break the record. On his third attempt he was killed when his Gee Bee spun out of control due to an aileron flutter problem.