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] Data from Aircraft Engine Historical Society[5] and Race With the Wind By Birch Matthews [citation needed] Comparable engines Related lists Preceded by US patrol boats - Followed by PTF boat