The Packard V-12 PT Boat Engine

The PT

boat

s made by Elko Higgins and Hawkins were lightning fast and all powered by Packard V12

engine

s of similar types, even before the renowned plywood derby nailed down the final

boat

designs the

engine

s had already been developed and were managers for the navy. All PT boats used in WWII were powered by these beefy V12 engines about which there is quite a bit of misunderstanding, let's take a look at what they were and what they weren't. There is a common misconception that these were the Packard-built versions of the Rolls-Royce. merlin aero engine known as v-1650 this is incorrect, the

packard

merlin did not come into operation until 1941 and at that time they were all pre-ordered for urgent aircraft production, no surplus units were available until 1943. the other common mistake is which were the previous

packard

liberty l-12 engines, which is also incorrect.

This error is compounded by the existence of an inverted version of the liberty engine that receives the same v1650 designation, although it was used earlier. First let's take a look at the liberty l12 as this is the granddaddy of the pt ship engine when the united states declared war on germany in may 1917 there was an immediate need for airplanes and a robust, powerful and light engine with which to power them the boss The Aircraft Production Board summoned two prominent designers, one Jesse G Vincent of the Packard Motor Company and Albert J Hall of the All Scott Motor Company to the Willard Hotel in Washington DC and basically locked them there until they came up with a suitable design; the engine was needed for over a dozen aircraft projected by aircode dh4 up to the xhb1 heavy bomber, guess they missed family life because in just five days they had come up with the drawings for a 1640 cubic inch displacement 45 degree v12 with cams in head, 2 valves per cylinder and liquid cooling.

Packard built a working prototype. Well, and I made the projected 400 horsepower and that was approved in August late fall, the war department placed orders for 22,500 engines now designated the L-12 or Liberty 12. With Packard Buick Ford Lincoln Cadillac and Mormon Hull Scott had no production. ability to get an order close to 20,000 engines had been delivered when the end of the war marked the end of production with the Packard engine finished number 6500 on June 4, 1919 although this engine had a similar displacement to the Merlin the other similarities They are quite A major difference between the L12 and the Merlin is that the Merlin's cylinders are cast in upper and lower cylinder blocks, while the L12 has 12 individual cylinders with integrated cylinder heads, compared to single cylinder head castings. piece of the Merlin, the L12 had a 45 degree angle.

V angle versus a more conventional 60 degree angle on the Merlin. Thanks, the next interwar iteration of this engine was very different. The 45-degree V angle was expanded to the more common and better-balanced 60 degrees, where the Liberty engine looks a bit like six Harleys strapped together. Overall, the new engine is more like a modern car V12. The stroke was reduced from seven inches to six and a half inches, while the bore was increased from five inches to six and three-eighths of an inch, resulting in a swept volume of 2,500 cubic inches. See where Packard's model numbers come from now, where the L-12 had one-piece cylinders and heads.

The new unit had four steel cylinders with the combustion chamber integral with the cylinder, but used an aluminum valve covering port unit which, like a cylinder head, had the intake and exhaust ports for the four valves, the guides valves, water jackets and camshaft bearing pedestal all integrated, all bolted to the top of the closed cylinder. An advantage of this idea is that there is no head gasket to blow or leak. due to exposure to combustion pressure or coolant, with this change the entire valve train was now closed, the bevel gears and shaft drive for the camshafts were retained, but the points and ignition coils that The 12-cylinder cams driving the cams were abandoned in favor of two magnetos and 12-cylinder distributors.

The earlier units have throttle lever slave timing advance control, while the later ones are completely manual. Lubrication is handled by a dual circuit oil pump with one three gear rotor configured to transport the oil to the external oil tank and two to provide pressure to the bearings and feed oil injectors the first generation one eight 2500 of 1924 produced around 600 horsepower this engine was a commercial failure compared to the l12 with only a few hundred built the unit was slowly developed to power aircraft such as the martin t3m and boeing tb the last 5a 2500 of 1930 was supercharged and produced 1,500 horsepower in emergency power configuration, which was impressive for the time, even with the war over and aircraft design in motion, sales didn't really take off with total production figures of only hundreds for reference.

The most popular version, the 800 horsepower 3a, sold for about $20,000. During this time, the Army Air Corps had shown little interest in this engine or the aircraft it powered, so obviously when the Navy arrived and asked for a marine version, Packard was also too much. I'll be happy to help you if you've ever wondered why Liberty engines cost a pretty penny and Packard 2500 series units are so scarce. Now you know, God, the marinized version started with you guessed it, the One M 2500, the 3M 2500 was the model installed on the first Elkos. The 77ft boats were later upgraded to 4m and 5m models, although not many 5m units entered service before the end of the war as a marine unit.

Exhaust manifolds must be water cooled or risk melting at higher loads. The collectors are welded fabrications. which have flanges on both ends, one for installing the exhaust pipe and the other for draining coolant from the manifold. They can be changed one way or another, allowing the exhaust to exit either end of the engine. A five-inch exhaust system. It was specified for each bank of cylinders and with those long drain tubes installed they make an impressive route. Remember that on 77-foot Elko boats, the two outboard engines drive their propellers through a V-drive, while the center engine is mounted further forward and has direct drive in most cases.

The engines included a fresh water pump and a raw water pump, although they could be obtained without a water pump if necessary. Packard crate engines will have the complete ignition system. Carburetor. Starter generator. Reverse drive. Fuel pump. Oil pumps and oil tank. They did not come with a heat exchanger for the cooling system, fuel system instrumentation or much else, despite the marine application, the M series continued with its two spark plugs per cylinder, all engines were supplied with starter motors. 24 volts and DC generators with fairly primitive voltage regulators set up on output. 28 volts, the regulators are electromechanical, have complex service needs and, like many of the other systems, require frequent adjustments to function properly, not only did the voltage output need to be set on each unit, but the voltages also needed to be balanced. three in a boat pt.

Now add the fact that the regulator output will increase as the unit reaches working temperature and you can see how a mechanic might be chasing his own tail trying to do this; You can see on these pages of the service manual how many tasks had to be done. They are performed at various intervals, some of which could be performed on-site and others requiring the engines to be removed. These engines are designed as aero engines from the start, built fairly lightly and are proven reliable with the maintenance schedule shown in the manual, but they are going to get finicky with poor fuel or when you skip the service work, the guys you see here swap engines they don't do it because the gym is closed like many aero engines, they have an overhaul life set at 750 hours at that time during the entire process.

The unit is supposed to be completely reconditioned. The 4m engine still had some variations between models, such as cooling arrangements and spark advance controls, but most importantly, later versions gained an improved supercharger that was more efficient and allowed for higher boost pressure. . The rating jumps from 350 horsepower to 1500 boost limits, however, they depend on the octane of the fuel and it is decided that the engine will run on 100 octane. They have gasoline. They can run on 91 octane fuel, but with the penalty that the maximum boost pressure is reduced. However, it can be left alone. To run the engine on 87 octane gasoline, it is necessary to reduce both timing and boost, which obviously reduces power output quite a bit.

Total production was over 12,000 units, so it was much more profitable for a baler than the A series had been. The final 5m unit has an aftercooler built into the manifold, although I'm not sure if It was used for more power or as a reliability improvement. The last working examples of these engines are installed on the Higgins-built pt658 located in Portland, Oregon. you