[1] By the time Lawrance merged with Wright, it had already developed the more powerful J-2, a version of the J-1 with slightly enlarged bore and displacement.

The changes improved the engine's reliability, cooling, and fuel consumption, but the basic design, dimensions, and performance were unaltered.

[1] The J-5 Whirlwind, introduced in 1925, was a complete redesign of the engine with greatly improved cooling and breathing, further increasing its reliability and reducing fuel consumption.

Among the visible changes was the much wider separation between the valves, for better cooling airflow, and completely enclosed, instead of exposed pushrods and rocker arms.

In a 1928 report on transcontinental aviation, the author disclosed the cost of a typical five-seat commercial aircraft as $12,500, of which $5,000 was for one of the 350 200 hp Whirlwind Engines available that year.

The most famous of these is Charles Lindbergh's solo transatlantic flight from New York City to Paris on May 20–21, 1927, in the Spirit of St. Louis, powered by a single Whirlwind J-5C.

[10] The New England Air Museum in Windsor Locks, Connecticut, has a Lawrance J-1, the Whirlwind's direct predecessor.