Guiberson diesel radial engine
An obscurish diesel aero engine that was test flown in a Stinson Reliant. Sadly, WW II intervened and it was used to power tanks instead. After the war it was forgotten. Some info links below:
http://www.oldengine.org/members/die.../Guiberson.htm
http://www.enginehistory.org/Diesels/Ch3.pdf