Packard 1A-2500

1A-2500
A preserved Packard 3A-2500 on display at the National Museum of the United States Air Force
Type	Liquid-cooled V12 engine
National origin	United States
Manufacturer	Packard
First run	1924
Number built	258

The Packard 1A-2500 is an American V-12 liquid-cooled aircraft engine designed by Packard in 1924 as a successor to the World War I-era Liberty L-12.^[1] Five aero variants were produced, of which the 3A-2500 was the most numerous. Three marine versions, used most prominently in American World War II PT-boats, the 3M-2500, 4M-2500, and 5M-2500, were also derived from it.^{[citation needed]}