1943 Packard Liberty PT Boat Engine
2,490 cid, V-12, 1,500 bhp

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Vehicle Specifications Quick Reference GuideYear: 1943 Make: Packard Model: Liberty Style: PT Boat Engine AAG#: 0008 Engine: V12, 2490 cid, 60-degree Transmission: VIN/Serial #: • Used as primary U.S. PT (Patrol Torpedo) boat engine during WWII • Packard Liberty 4M-2500 • 1,200 hp initially, 1,850 hp later • Engine was based on the 1925 liquid cooled Liberty aircraft engine • Nominal range was 350 nautical miles, running at 23 knots cruising speed. The next logical development after the invention and perfection of the self-propelled torpedo was the torpedo boat. At one stroke, these diminutive vessels put other navy ships in considerable risk. The torpedo boats were simple to produce, arm and man, and thus were quickly fielded in large numbers. The additional attributes of the ubiquitous boats:speed, stealth, and ability to operate in restricted waters. These attributes made the torpedo boats ideal for many other varied assignments, thus the patrol and torpedo boat was born. (Also interesting, the next logical development after the torpedo boat was a somewhat larger vessel, which was relatively fast and could out-gun and defeat the torpedo boats: the Torpedo Boat Destroyer. With the name quickly shortened to “Destroyer,” this vessel has continued to undergo significant development since its inception before World War I, and today has displaced the once mighty Battleship as the Queen of the majority of the world’s navies.) A rapid development program for Patrol Torpedo (PT) boats began once it became apparent that the U.S. was going to get into a war in the Pacific with Japan. These boats needed to be produced quickly and at low cost so large numbers could be obtained rapidly. In order to help minimize cost and to support rapid development, an off-the-shelf marine engine was selected. Packard had a production line in place for the Liberty marine engine, which was eventually selected.The Packard 4M-2500 V12 engine was utilized in almost all U.S. Navy World War II PT boats. This engine was based on the 1925 liquid cooled Liberty aircraft engine (originally intended for the Huff-Daland Keystone LB-1 Liberty bomber, under development at the end of World War I), but was later significantly redesigned by Packard for use in racing boats. The Packard Liberty had 2,490 cid and developed 1,200 hp in the early versions – this was later increased to 1,850 hp. Three of these ngines were installed in PT boats, each running an independent propeller. Primary armament was two or four 21-inch torpedoes. The Elco machine guns mounted in open rotating turrets. (These turrets were designed by the same company that would later produce the Tucker automobile). Nominal range was 350 nautical miles, running at 23 knots cruising speed. The Elco (Electric Launch Company) class boats were the most prevalent, over 400 of these being produced. Famous PT boats of this class include PT-109 (commanded by later President John F. Kennedy) and PT-41 (which evacuated General Douglas MacArthur from the Philippines). Famous PT boat actions range from attacks on significantly more powerful forces, such as at Surigao Strait during the Battle of Leyte Gulf where a Japanese cruiser was sunk by relentless U.S. PT boat attacks (October 25, 1944), to more mundane, but essential tasks such as rescuing downed flyers and survivors of ships gone down, and infiltration of intelligence teams on to the countless islands on the march to Japan. These boats were considered expendable, and large numbers were lost.

In an interesting sub-plot to the Liberty story, Henry Leland (who took over Henry Ford’s floundering first attempt at a production automobile and turned it into a success under the name Cadillac), left Billy Durant’s General Motors (which had subsequently bought Cadillac to become the luxury brand of GM, and brought Leland into GM with it) to produce the Liberty engine in support of World War I effort. Leland formed Lincoln Motor Company (named after one of his boyhood heroes, Abraham Lincoln) in 1917 to build the Liberty aircraft engine. With the sudden end of the World War I the Liberty engines were no longer needed, and in order to recoup the considerable investment Leland had made in the Lincoln factories, they were retooled to manufacture the Lincoln luxury automobile. Continuing financial troubles, based in part on the Liberty engine manufacture attempt, subsequently forced Leland to sell Lincoln to Henry Ford, to then become the luxury brand of the Ford Motor Company and compete directly against Cadillac. Unfortunately, after initiating both the Cadillac and the Lincoln luxury cars, the gifted and influential Leland left he automobile industry at this point. Like the venerable Destroyer, the PT Boat has also continued to evolve over the years. Like the Destroyer, the newer patrol and attack craft usually tend to be somewhat larger than the World War II vintage boats. Extensions of the small, light and swift PT Boat concept include the much faster hydrofoils developed by Boeing; the hard-fighting Riverine boats used by the U.S. Navy on the rivers of Viet Nam (and seen to great effect in the film “Apocalypse Now”); and various larger and smaller types in use in the rivers and littoral waters of Iraq today. Perhaps the ultimate development of PT Boat type comes with the addition of nuclear capable torpedoes and nuclear capable cruise missiles. The likely transfer of this technology to China from the former Soviet Union adds a particularly disturbing dimension to any potential conflict in the restricted straights between the island of Formosa and mainland China.


  • Based on the V-8 and V-12 Liberty marine and aircraft engines that Packard had been building since WWI; 3 engines per 80-ft, 50 ton PT boat: 42 knots (50 mph) max speed; 500 gallons per hour; 1400+ Packard PT boat engines produced during WWII