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I've been studying the history of early aircraft engines since I visited the National Air & Space Museum a month ago. It really is astonishing how fast new tech was designed, prototyped, and put into production.

In 1903, the Wright Brothers needed a lightweight gasoline engine. They calculated that they needed an engine that produced at least 8 horsepower and weighed no more than 200 pounds.. A quick survey of the automotive market showed there was no such engine available and they would have to make their own. They had the block cast in Dayton and their mechanic Charlie Taylor machined the parts and assembled the engine. He later described his work: "We didn’t make any drawings. One of us would sketch out the part we were talking about on a piece of scratch paper, and I’d spike the sketch over my bench. It took me six weeks to make that engine. The only metal-working machines we had were a lathe and a drill press, run by belts from the stationary gas engine."

Just 14 years later near the end of WW I, more powerful and higher altitude was needed.

As WW I unfolded in Europe, Packard Company president Henry B. Joy grew ever more concerned and realized that the fledgling and largely disorganized American aircraft industry would need a more powerful engine for its aircraft fleet. In December 1914, Jesse Vincent, the Packard Company's chief engine designer, got the inspiration to combine two sixes into a V-12 configuration. Initial prototypes were limited to 289 cu. in. (4.7 liters) to permit testing in a race car that was restricted by automobile racing regulations to a maximum 300 cu. in. displacement engine. This prototype engine worked well, and soon its displacement was eventually boosted up to 905 cu. in. That effort came to fruition in 1915 when the design ofthe "Twin Six" engine was complete. This experimental engine weighed 817 lbs and produced 110 HP, and went on to set several automotive race track records. The second iteration of this engine was known as the "905", referring to its cubic inch displacement. It weighed 979 lbs. and developed 275 HP at 1600 rpm. The "905" was perfected and marketed as the automotive "Twin Six", and installed in an unprecedented 10,000 production automobiles in 1916.
America entered the war on 6 April 1917, following the attack and sinking o f the civilian transport ship Lusitania. At this time, Packard had the third version o f the "905" engine under development and had already invested nearly two years and $400,000 ofcompanyresources into the latest automobile engine. Feeling the need to aid the war effort, company president Alvan Macauley (Hemy Joy's successor) offered his company's resources, knowledge and facilities to the government. Although it makes perfect business sense, perhaps it would be pure speculation to suggest that they might have been thinking, " If the government is about to buy a lot of aircraft engines for the Army planes it surely will build and send across the Atlantic, then those engines may as well be Packards!"
The company representative Macauley had sent to Washington DC was Vincent, their chief engine designer. Vincent met with Aircraft Production Board members Edward Deeds and S. Waldon (a former sales manager ofPackard) and proposed that a standardized Army aircraft engine be procured for all Army aircraft, and that it be Packard's "905" design. Vincent reinforced his proposal with the statistic that, at the time, the British and French had developed 83 different types o f aircraft engines and likely warned his audience of the logistics nightmare of trying to maintain an American and Allied aircraft engine fleet of that composition. He also added that the Germans, in comparison, were flying only eight engine types. They, in turn, asked Vincent to confer with E. J. Hall, another engine expert from the San Francisco, California based Hall-Scott Motor Car Company who, coincidentally, also happened to be in Washington DC with a similar proposal. Vincent and Hall conferred for three days and nights, along with Dr. Samuel W. Stratton of the Bureau of Standards. They were given the task of designing as rapidly as possible an aircraft engine that would rival if not surpass those of Great Britain, France, and Germany. The Board specified that the engine would have a high power-to-weight ratio and be adaptable to mass production.
On 21 May 1917, it was decided that an engine combining the features of the Packard V-12 "905" engine and the Hall-Scott V-12 "A-8" engine was to be the Army's new standard aircraft engine. Knowing that several companies would be building it under contract for the government, they felt a more "neutral" name was desirable. Thus, the "Liberty'' engine was born.
The Board brought Vincent and Hall together on 29 May 1917 at the Willard Hotel in Washington, where the two were asked to stay until they produced a set of basic drawings. After just five days, Vincent and Hall left the Willard with a completed design for the new engine, which had adopted, almost unchanged, the single overhead camshaft and rocker arm valvetrain design of the later Mercedes D.IIIa engines of 1917–18.
In July 1917, an eight-cylinder prototype assembled by Packard's Detroit plant arrived in Washington for testing, and in August, the 12-cylinder version was tested and approved. The Liberty engine was formally announced on 4 July 1917.
In the fall of 1917, the War Department placed an order for 22,500 Liberty engines, dividing the contract among the automobile and engine manufacturers Buick, Ford, Cadillac, Lincoln, Marmon, and Packard.

From a joint design in May to a prototype in July and a production order for 22,500 in the fall -- less than six months!

So the great American development and production ramp-up of new technologies that occurred in WW II ALSO occurred in WW I.