This is a picture of the Ford GAA, 1100 cubic inch tank engine used in some Sherman tanks, and in some newer tanks during WW2. It was an all aluminum block and cylinder head, double overhead cam, 4 valve per cylinder monster of a V8. It produced "only" around 500 hp due primarily to it's very low compression ratio for the lousy automotive gas of the time. It made prodigious torque at very low RPM. It began life as a V12 that Ford designed and built hoping to win an Army Air Force contract for an aircraft engine. Ford lost that contract to Allison. When the Army issued an RFP for a tank engine, Ford lopped 4 cylinders off the V12, and the GAA V8 was born.
A question I've always had tho is why Ford didn't scale the GAA down to around 300 cubic inches or so after the war and put it in some of their automobiles. The basic tooling already existed. Would have only been a matter of scaling the existing design down. It was way ahead of it's time design-wise. Instead, Ford continued to use their largely obsolete flathead V8 until some time in the early, maybe mid 50's, I'm not sure.
A 300 CI version of the GAA would have easily tripled the anemic output of the old flathead v8. As the quality and octane levels of post WW2 gasoline climbed, a smaller GAA's output, with higher compression and more aggressive cam timing, would have soared.
Had Ford done that, IMO, the horsepower wars that began in the mid 50's and continued until 1971, would have come to an early conclusion, unless similar designs from GM and Chrysler were developed.
The above is only a mental exercise, but something I've wondered about from time to time.