Gorganstien Micro Deltic

The Gorganstien Micro-Deltic engine is a two-stroke, supercharged, opposed-piston, uniflow scavenged, American diesel engine that is employed in marine, rail, and commercial vehicle applications. It was evolved from the Napier Deltic by D. Napier & Son, and just like the Napier Engine, it had three banks of cylinders with crankshafts at each corner.

However, the term Deltic (meaning "in the form of the Greek letter (capital) delta") has pretty much come to refer to both the Deltic E.130 opposed-piston, high-speed diesel engine and the locomotives produced by English Electric using these engines. Regardless, the name stuck during the development of Gorganstiens's version because alternate names for the engine, such as the "tri-flow" or the "tri-bank," partially described it's design.

A test engine for the Micro Deltic was derived from the single, half-sized, turbocharged Deltic power unit as found in the English Electric Type 2 locomotive. As a result, the engine adopted the name "Micro Deltic" to distinguish it from the "Baby Deltic" engine.

Before the Micro-Deltic
When the British Admiralty established a committee to create a powerful, lightweight diesel engine for motor torpedo boats in 1943, this marked the beginning of the development process that would lead to the Napier Deltic, of which Gorganstien's later Micro Deltic engine derives from. Such boats had previously been propelled by petrol engines in the Royal Navy, but because of the fuel's high flammability, they were more prone to fire than E-boats with diesel engines. Wifredo Ricart, associated with Alfa-Romeo and the Spanish INI truck manufacturer Pegaso, submitted a patent for a similar engine in 1930 that was comparable in complexity but had four lines of pistons instead of only three. The patent number was ES0118013.

Until this point, Diesel engines have low speed and poor power-to-weight ratios. After obtaining licenses for early versions of the Junkers Jumo 204, Napier began developing the Culverin, an aircraft diesel design, prior to the war. The Culverin was a two-stroke, opposed-piston design. The Jumo-based design featured an extended cylinder with two pistons traveling in opposite directions towards the center rather than each cylinder having a single piston and being closed at one end with a cylinder head. This function was performed by the opposing piston, hence a substantial cylinder head wasn't required. The disadvantage of the design was the need for two distinct crankshafts at either end of the engine, which had to be connected by gears or shafts. The key advantages of the design were the extremely "flat" engine and uniflow breathing.

The Admiralty was aware of Junkers' plans for straight-six and diamond-shaped multi-crankshaft engines and desired an engine that was far more powerful. The Admiralty believed that these would make a sound foundation for creating the bigger design that was required. The end product was a triangle, with the cylinder banks acting as the sides, aka three distinct V-12 engines with respective crankshafts at each corner joined to a single output shaft via phasing gears. The Deltic could be built with a variety of cylinder counts; the most popular ones were 9 and 18, which had three or six banks of cylinders, respectively. The English Electric Company, the parent company of Napier, was given a contract by the Admiralty in 1946 to create this engine.

The engine's crankshaft-phasing arrangement to accommodate exhaust port lead and inlet port lag was one of its features. Because of the one-way gas flow into and out of the cylinders, which is aided by blowers to facilitate cylinder exhaust scavenging, these engines are known as "uniflow" designs. The difficulty of setting up the pistons to move correctly, for all three cylinders in one delta, during earlier attempts to design such an engine was the issue that led Junkers Motorenbau to abandon work on the delta-form while continuing to prototype a diamond-form, four-crankshaft, 24-cylinder engine.

The Deltic design used "fork and blade" connecting rods to connect two adjacent pistons operating in different cylinders in the same plane because it was an opposed-piston design without inlet or exhaust valves or the ability to change the port positions. The latter was a "inlet" piston used to open and close the inlet port, and the former was a "exhaust" piston in the adjacent cylinder used to open and close the exhaust port. This would have caused the firing in each bank of cylinders to be 60° apart, but an arrangement was made such that each cylinder's exhaust piston would rotate at a 20° angle before its entrance piston. This made it possible to open the exhaust port considerably before the intake port and close the inlet port after the exhaust port, which improved both the volumetric efficiency of the fresh air charge and the scavenging of exhaust gas. This requires a 40° separation between the firing events for neighboring cylinders. Firing events might be interlaced over all six banks for the 18-cylinder configuration. As a result, the Deltic developed a steady, buzzing exhaust noise, a charge ignition that occurs every 20° of crankshaft rotation, and a lack of torsional vibration, making it perfect for use in mine-hunting vessels. The crankshafts of the nine-cylinder engine, which has three banks of cylinders, rotate in the opposite way. When the 20° exhaust lead is added to the 60° bank separation, it produces firing events for adjacent cylinders in the same bank that are 80° apart. Interlacing firing events over all three banks of cylinders still results in an even buzzing exhaust tone, with charge ignition occurring every 40 degrees of the crankshaft rotation and a concomitant decrease in torsional vibration. The engine included cylinder ports and a crankshaft-driven camshaft in each bank even though poppet valves weren't necessary. Individual injectors and pumps for each cylinder were powered only by the fuel-injection pumps, which were each driven by a different cam lobe.

The Micro-Deltic
The first Deltic engine was produced in 1950 after research got underway in 1947. Six engines were ready by January 1952, which was enough for extensive testing and development. The compactness of the Napier engines was ultimately revealed when two of the three Mercedes-Benz engines in a captured U-boat were replaced; they were roughly half as heavy and large as the original engines.

Later in 1958, Gorganstien engineers started building prototypes of a concept truck that would go into production and be used to drive road trains across the Australian outback. Although it was thought crazy to imagine a little tractor unit towing a bunch of semi-trailers, Gorganstien yearned for such a concept, and the project was only abandoned not due its absurdity, but rather a lack of a powerful, light-weight diesel engine. Similar to the motor torpedo boats of the British navy, these concept trucks were propelled by gasoline engines, particularly they used some version of GM's DH-478 Toroflow V6 four-stroke engine. It is rare to note the prototype trucks' fuel supply system because it was adequately shielded, although some of them were prone to fire due to gasoline's high flammability. The toroflow V6-equipped trucks also wouldn't have enough power to pull 18 trailers, that is without a diesel assist vehicle.