Otto Cycle Solved Problems
On the figure we show a plot of pressure versus gas volume throughout one cycle.
Thermodynamics deals only with the large scale response of a system which we can observe and measure in experiments.
For the ideal four stroke engine, the intake stroke (1-2) and exhaust stroke (6-1) are done at constant pressure and do not contribute to the generation of power by the engine.
During the compression stroke (2-3), work is done on the gas by the piston.
During the constant-volume heating, 340 Btu are added per cycle.
At the beginning of compression the volume is 6 cu ft, the pressure is 13.75 psia and the temperature is 100F.