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FJR Motorcycle Forums
Technical & Mechanical Problems
Fuel Economy and Smoothness without Compromise
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<blockquote data-quote="charismaticmegafauna" data-source="post: 860865" data-attributes="member: 665"><p>From a Franz Hofmann paper:</p><p></p><p>"The single biggest robber of engine efficiency is the simple throttle! As an example, in a large 7 liter engine, each cylinder is almost one liter in size. With the throttle almost closed, (and with the engine intake manifold vacuum at 18" HG, or approximately 62% of absolute vacuum or zero psi absolute pressure) imagine trying to lift a plunger 4". You would be lifting 208 lbs.! (Assume a 4.25" bore, equaling 14.17 square inches, times 14.7 lbs/sq/in air pressure at sea level.)</p><p></p><p>Take this one step further, and multiply it times the number of cylinders, and you have some kind of idea how much power it takes to just spin an engine over without any combustion process taking place!"</p></blockquote><p></p>
[QUOTE="charismaticmegafauna, post: 860865, member: 665"] From a Franz Hofmann paper: "The single biggest robber of engine efficiency is the simple throttle! As an example, in a large 7 liter engine, each cylinder is almost one liter in size. With the throttle almost closed, (and with the engine intake manifold vacuum at 18" HG, or approximately 62% of absolute vacuum or zero psi absolute pressure) imagine trying to lift a plunger 4". You would be lifting 208 lbs.! (Assume a 4.25" bore, equaling 14.17 square inches, times 14.7 lbs/sq/in air pressure at sea level.) Take this one step further, and multiply it times the number of cylinders, and you have some kind of idea how much power it takes to just spin an engine over without any combustion process taking place!" [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
Fuel Economy and Smoothness without Compromise
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