IC Engine Questions and Answers – Knocking in S.I. Engine

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This set of IC Engines Multiple Choice Questions & Answers (MCQs) focuses on “Knocking In S.I. Engine”.

1. In a spark ignition engine combustion which is initiated between the spark plug electrodes spreads across the combustible mixture.
a) True
b) False
View Answer

Answer: a
Explanation: None.
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2. A definite flame front is one that separates the fresh mixture from the products of combustion travels from the spark plug to the other end of the combustion chamber.
a) True
b) False
View Answer

Answer: a
Explanation: None.

3. The process of autoignition has nothing to do towards engine knock.
a) True
b) False
View Answer

Answer: b
Explanation: Actually, the process of autoignition leads towards engine knock.
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4. In SI engine, ignition lag is reduced if the initial temperature and pressure are _____________
a) decreased
b) increased
c) constant
d) none of the mentioned
View Answer

Answer: a
Explanation: In SI engine, due to the increment of the initial temperature and pressure are ignition lag is reduced.

5. Auto ignition refers to the initiation of combustion without the necessity of a flame.
a) True
b) False
View Answer

Answer: a
Explanation: None.
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6. What are the effects of knocking?
a) noise and roughness
b) mechanical damage
c) carbon deposits
d) all of the mentioned
View Answer

Answer: a
Explanation: The effects of knocking are
i) noise and roughness
ii) mechanical damage
iii) carbon deposits
iv) increase in heat transfer
v) decrease in power output and efficiency
vi) preignition.

7. What are the effects of knocking?
a) increase in heat transfer
b) decrease in power output and efficiency
c) preignition
d) all of the mentioned
View Answer

Answer: a
Explanation: The effects of knocking are
i) noise and roughness
ii) mechanical damage
iii) carbon deposits
iv) increase in heat transfer
v) decrease in power output and efficiency
vi) preignition.
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8. Increase of pressure increases the self ignition temperature and the induction period.
a) True
b) False
View Answer

Answer: b
Explanation: In fact, increase of pressure decreases the self ignition temperature and the induction period.

9. Low engine speeds will give low turbulence and low flame velocities and knock may occur at low speed.
a) True
b) False
View Answer

Answer: a
Explanation: None.
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10. Use of low octane fuel can eliminate detonation.
a) True
b) False
View Answer

Answer: b
Explanation: No, but the use of high octane fuel can eliminate detonation.

Sanfoundry Global Education & Learning Series – IC Engine.

To practice all areas of IC Engine, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn | Youtube | Instagram | Facebook | Twitter