Consider the mechanical cycle associated with the four-stroke spark-ignition engine illustrated in Fig. 1.14. The combustion process begins near the end of the compression stroke and ends shortly after the expansion stroke begins. A typical plot of the cylinder pressure as a function of the cylinder volume is shown in the sketch below. Redraw the sketch and label the beginning and end points of each of the four mechanical strokes. Also, indicate the beginning and end of the combustion process. For each stroke, write a sentence describing why you selected the specific beginning and end points.

Inlet Exhaust Inlet Exhaust (a) Intake 0000 Inlet Exhaust Inlet Exhaust (b) Compression (c) Expansion (d) Exhaust