Two Wright R-2600 engines.
In 1942, Doolittle and his squadron took off in B-25's from the aircraft carrier USS Hornet 400 miles farther out from Japan than they wanted to after being spotted by a Japanese fishing boat. After dropping their bombs on Tokyo they turned west toward China, hoping to land there. Some of the aircraft ran out of fuel and crashed into the ocean, some made it to China and crashed there after running out of fuel, and one landed safely in the Soviet Union where the aircraft was confiscated and the crew was imprisoned..