Engine Characteristics
editThe 6-71 is a six cylinder engine, which are "inline" or in a straight line.[1] This type of engine is commonly referred to as an "inline six." The 71 refers to the displacement per cylinder which is 71 cubic inches.[1] The firing order of the engine, or the order combustion occurs in which cylinder, is 1-5-3-6-2-4.[1] The engines compression ratio is 18.7:1 with a 4.250 bore and a 5.00 inch stroke.[1] The engine weighs 2185 pounds and is 54 inches long 29 inches wide and 41 inches tall.[1] At 2100 Revolutions Per Minute the engine is capable of producing 230 horse power, and 172 kilowatts.[1]
Engine Operation
editThe 6-71 is a two stroke diesel engine.[2] Air is provided to the engine via a supercharger.[1] However, on some models of the 6-71 both a supercharger and a turbocharger can be utilized.[2] Fuel is proved by six, Port and Helix fuel injector pumps, or Jerk pumps.[3] The amount of fuel injected into the engine is controlled by the governor.[1] The governor senses the revolutions of the supercharger to control the amount of fuel injected into the cylinders. More fuel is added for faster speeds and the amount of fuel is lessened when the speed of the engine is reduced. Ignition of the fuel occurs when the piston compresses the fuel-air mixture to a point that it reaches a temperature to combust.[1] The timing of the engine or the order in which fuel and air are added or removed, is controlled by an engine driven camshaft.[2] Depending on the application of the engine, boat or truck, the engine can be water or air cooled. The engine has its own cooling liquid called Jacket Water, the two options for cooling are to cool the Jacket Water.[3] If the engine is in a truck or land based operation then the Jacket Water is cooled by air through a device like a radiator in a car. In a boat an alternative method of cooling is available, which is water cooling or to take the cool water around the boat and pass it by the warm Jacket Water in whats called a heat exchanger.[3]
Engine History
editThe Gray Marine 6-71 Marine Diesel Engine was not built from the ground up by Gray Marine Motor Company. In fact, it was a retrofitting of the already popular and well used General Motors 6-71 diesel engine that cold be seen in places like tractors and farm machines, but mostly is famous for its use in the M4 Tanks, also known as the Sherman tank[4] Gray picked up the contract to convert the engine over for marine purposes, and the Gray Marine 6-71 became a reality. Since then the 6-71 has seen little iconic use other than in the famous Higgins LCVP, the famous D-Day landing craft [4].
When Higgins saw the suggested model for the D-Day landing craft, as suggested by the world's top boat designers, Higgins said , as a newspaper quoted "something to the extent of 'This boat is lousy' and 'this boat stinks' [4]. The then oddly shaped soup bowl like shaped boat the came from the recesses of Higgins mind that could not only beach, but then pack up and head back out to the fleet was dubbed the LCVP and then the most powerful engines in the marine world were placed inside. The founder of Gray on June 6th, 1944 commented to a local newspaper that his greatest dream was achieved that day, that when the crafts carrying US soldiers into Normandy for the invasion, they were driving Gray Marine diesel engines [4].
References
edit- ^ a b c d e f g h i Barrington Diesel club. "Detroit Diesel 6-71 engine specs at Barrington Diesel Club". Retrieved 11 April 2012.
- ^ a b c Tugboat Enthusiasts Society of the Americas. "DETROIT DIESEL INLINE 71 SERIES". Retrieved 11 April 2012.
- ^ a b c G.M. Grey Marine Model 64 HN9. Seattle, Washington: Hatch and Kirk INC.
- ^ a b c d Grayson, Stan (1999). Engines Afloat. Devereux Books. ISBN 0-6940070-7-X.
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