VALVE TIMING DIAGRAMS

Valve Timing Diagram for Four Strokes SI Engines

Valve timing diagram is a graphical representation of valves opening and closing time with ignition time in terms of angle of crank revolution. Figure 6.12 shows the valve timing diagram for low speed four strokes SI engines. Practically valve cannot be opened or closed at any sharp points. Therefore, the actual indicator diagram differs from the theoretical indicator diagram as shown in Figure 6.15.

Theoretical timings for valves of 4-s CI engines is summarized in Table 6.3.

Figure 6.12 Valve Timing Diagram for Four Strokes Engines

Table 6.3 Theoretical and Actual Valve Timing for Four Strokes SI Engines