Figure P2.3 shows the typical variations of pressure difference due to thermal shock as a function of crankshaft position for different spark timings, engine loads (BMEP), engine speeds, and operating air-fuel ratios. Discuss the effect of
thermal shock on pressure measurement by explaining the trend observed with different engine operating parameters. Explain the reasons why maximum thermal shock occurs at 2000 engine speed instead of 1000 rpm (Fig. P2.3c). Thermal shock is also highest for stoichiometric (λ ¼ 1) engine operations (Fig. P2.3d). Justify this observation with the explanation of combustion process.