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Originally posted by drz
Each rotor in a rotory engine has a power stroke once for every one rotation of the centric shaft, whereas in a 4-stroke piston engine, each piston has a power stroke ever 2 revolutions of the crankshaft. So a rotory engine is effectively equivalent to a piston engine of twice the size when considering the volume displaced during the power stroke for every rotation of the output shaft.
Each rotor in a rotory engine has a power stroke once for every one rotation of the centric shaft, whereas in a 4-stroke piston engine, each piston has a power stroke ever 2 revolutions of the crankshaft. So a rotory engine is effectively equivalent to a piston engine of twice the size when considering the volume displaced during the power stroke for every rotation of the output shaft.
The rotary engine has 6 power strokes per revolution, despite 2 "cylinders"
An equivalent 2 cylinder engine would have 1 power stroke per revolution -- so the guys at SCC might as well multiply the rotory's displacement by 6.
Unfortunately, the rotory's design isn't the most efficient in terms of combusting fuel. It's near impossible to get more than 9:1 compression out of it, and a small portion of each power stroke actually pushes backwards on the rotor. Additionally, you can't just make big rotors to increase the displacement as you reach a point where the flame simply can't keep up with the edge of the rotor -- instead you have to add more rotors (3 and 4...)
So SCC and all the other bonehead magazines can call it a 2.4/6 engine all they want, but the fact is the engine nominally displaces 1.2 and 1.3 liters and is in an entirely different class than the reciprocating piston engine...
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