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In piston engines, static compression ratio is determined using the cylinder volume when the piston is at the top and bottom of its travel. The compression ratio is the ratio between the maximum and minimum volume during the compression stage of the power cycle in a piston or Wankel engine.
The Pratt & Whitney TF30 used on the F-111 had a pressure ratio of about 20:1, while newer engines like the General Electric F110 and Pratt & Whitney F135 have improved this to about 30:1. An additional concern is weight. A higher compression ratio implies a heavier engine, which in turn costs fuel to carry around.
Compression tests should normally be done with all spark plugs removed to maximize cranking speed. Cranking compression is a dynamic test of the actual low-speed pumping action, where peak cylinder pressure is measured and stored. A compression tester. Leak-down testing is a static test. Leak-down tests cylinder leakage paths.
The mean effective pressure (MEP) is a quantity relating to the operation of a reciprocating engine and is a measure of an engine's capacity to do work that is independent of engine displacement. [1] Despite having the dimension of pressure, MEP cannot be measured. [ 2 ]
Crankcase-compression designs are often used in small petrol (gasoline) engines for motorcycles, generator sets and garden equipment. This design has also been used in some small diesel engines, however it is less common. Both sides of the piston are used as working surfaces: the upper side is the power piston, the lower side acts as a pump.
The 1KR-FE-engine used in the Toyota Aygo, Citroën C1 and Peugeot 107 amongst others is an example of a modern long-stroke engine widely used in FF layout cars. This engine has a bore and stroke of 71 mm × 84 mm (2.8 in × 3.3 in) stroke giving it a bore/stroke ratio of 0.845:1.
Small businesses are bracing for stiff tariffs that President-elect Donald Trump has proposed as one of his first actions when he takes office. Trump has proposed importers pay a 25% tax on all ...
The engine pressure ratio (EPR) is the total pressure ratio across a jet engine, measured as the ratio of the total pressure at the exit of the propelling nozzle divided by the total pressure at the entry to the compressor. [1] Jet engines use either EPR or compressor/fan RPM as an indicator of thrust. [2]