What type of engine was used in the planes used in the raid led by Colonel James “Jimmy” Doolittle?
Kawasaki Ki-61:  It was the only mass-produced Japanese fighter of the war to use a liquid-cooled inline V engine. Doolittle Raid:  The raid was planned and led by Lieutenant Colonel James "Jimmy" Doolittle of the United States Army Air Forces.
liquid-cooled inline V engine