We're Going to Need a Bigger V-8...

[Mike999]

Here's an interesting article on the massive Ford GAA V-8 engine that powered the M4A3 Sherman tank in World War 2. It started out as a V-12 aircraft engine - Henry Ford's attempt to compete with the famous 12-cylinder Rolls-Royce Merlin engine.

Since I build military stuff along with cars, the whole subject of Sherman motivation fascinates me.  It really was a case of necessity being the mother of invention.

M4/M4A1 Shermans:  they used radial aircraft engines. But as WWII started, those engines were desperately needed in airplanes.

M4A2: powered by a pair of GMC 6-cylinder Diesel truck engines.  The US Army hated that idea. To minimize supply headaches, it wanted all its vehicles to be gasoline powered.  It palmed off the M4A2 on Lend-Lease users like Britain, France and Russia.  And the U.S. Marines, who liked the M4A2; it could be re-fueled from any Diesel-powered US Navy landing craft, boat or ship.

M4A3: used the Ford GAA engine as mentioned in the article. 

M4A4: the Big Kahuna!  Chrysler built a 30-cylinder Godzilla of an engine it called the "A57 Multibank."  It was 5 MoPar 6-cylinder engines mounted around a common crank, and was so big the Sherman chassis had to be stretched for it to fit. Chrysler claimed it could still run if 12 of its 30 cylinders were dead.  The US Army hated that idea too, believing it would be a giant maintenance headache.  But in the field it was very well-behaved, and put to good use by Lend-Lease countries. 

https://www.warhistoryonline.com/instant-articles/v8-ford-gaa.html