8. Reciprocating Engine Performance Characteristics

Real engine cycles are routinely obtained experimentally in the form of plots of in-cylinder pressure p versus crank angle position 𝜃 and are widely used by engine manufacturers and researchers to assess the performance of engines. A p − 𝜃 plot or its derivative p − V plot is known as the indicator diagram, an example of which is shown in Figure 6.1. To examine the engine performance parameters from first principles, we will make use of the actual cycles of naturally aspirated (NA) spark ignition (SI) and compression ignition (CI) engines shown in Figure 8.1.