Top 50+ Solved Combustion in SI and SI Engines MCQ Questions Answer
Q. In SI engines maximum flame speed is obtained when the equivalent ratio is between
a. 1.1 and 1.2
b. 1.0 and 1.1
c. 1.2 and 1.3
d. less than 1
Q. In SI engines flame speed increases
a. with turbulence
b. with fuel-air ratio
c. both (a) and (b)
d. none of the above
Q. with increase in compression ratio flame speed
a. increases
b. decreases
c. remains the same
d. none of the above
Q. With increase in speed the crank angle required for fame propagation
a. increases
b. decreases
c. not affected
d. none of the above
Q. Increasing the compression ratio in SI engines the knocking tendency
a. decreases
b. increases
c. not affected
d. none of the above
Q. Decreasing the cooling water temperature in SI engines the knocking tendency
a. increases
b. decreases
c. not affected
d. none of the above
Q. Detonation in SI engines occur due to
a. pre ignition of the charge before the spark
b. sudden ignition of the charge before the spark
c. autoignition of the charge after the spark in struck
d. none of the above
Q. Desirable characteristics of the combustion chamber for SI engines to avoid knock is
a. small bore
b. short ratio of fame path to bore
c. absence of hot surfaces in the last region of the charge
d. all of the above
Q. In CI engines with increase in compression ratio the delay period
a. increases
b. decreases
c. first increases and then decreases
d. not affected
Q. Knocking takes place in CI engines
a. at the start of combustion
b. at the end of combustion
c. during combustion
d. none of the above
Q. In CI engines knocking tendency increases with
a. increase in compression ratio
b. increasing inlet temperature of air
c. decrease in compression ratio
d. increasing coolant water temperature
Q. In CI engines by increasing inlet air pressure the knocking tendency
a. increases
b. decreases
c. not affected
d. first decreases and then increases
Q. Open combustion chambers in CI engines require
a. high injection pressures
b. accurate metering of fuel by the injection system
c. both (a) and (b)
d. none of the above
Q. The advantages of the indirect injection combustion chambers are
a. low injection pressure
b. direction of spray is not critical
c. both (a) and (b)
d. good cold starting performance
Q. In CI engines the delay period is affected by
a. compression ratio
b. engine speed
c. output
d. all of the above