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# Answer number 2 please Question 1 An SI engine operating at 1200 RPM has a $10.2-\mathrm{cm}$ bore with the spark plug offset by $6 \mathrm{~mm}$ from center. The spark plug is fired at $20^{\circ}$ bTDC. It takes $6.5^{\circ}$ of engine rotation for combustion to develop and get into flame propagation mode, where the average flame speed is $15,8 \mathrm{~m} \mid \mathrm{sec}$. Calculate: (a) Time of one combustion process (i.e., time for flame front to reach the furthest cylinder wall). (b) Crank angle position at the end of combustion. Question 2 It is desired that flame termination be at the same crank angle position when the speed of the engine in Problem 1 is increased to 2000 RPM. In this range, flame development takes the same amount of real time and flame speed is related to engine speed as $V_{f}=0.92 n$. Calculate: (a) Flame speed at 2000 RPM. [m/sec] (b) Crank angle position when the spark plug should be fired. (c) Crank angle position when flame propagation starts.  