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Internal Combustion Engines (I.C. Engines) MCQ Questions & Answers | Mechanical Engineering

Learn Internal Combustion Engines (I.C. Engines) MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Internal Combustion Engines (I.C. Engines): MCQ question is the important chapter for a Mechanical Engineering and GATE students. Page-7 section-2

Each section contains 100 MCQs on Internal Combustion Engines (I.C. Engines) .
61
The brake power of a diesel engine, keeping other parameters constant, can be increased by
Discuss
Answer & Solution
Answer: Option C
Solution:
The brake power of a diesel engine, keeping other parameters constant, can be increased by Increasing the pressure of intake air
62
A supercharged engine as compared to an ordinary engine
Discuss
Answer & Solution
Answer: Option D
Solution:
A supercharged engine as compared to an ordinary engine:
- Requires smaller foundation
- Is lighter
- Consumes less lubricating oil
63
In a petrol engine, if diesel is used, then the engine will
Discuss
Answer & Solution
Answer: Option A
Solution:
In a petrol engine, if diesel is used, then the engine will Not run
64
A diesel engine as compared to petrol engine (both running and rated load) is
Discuss
Answer & Solution
Answer: Option A
Solution:
A diesel engine as compared to petrol engine (both running and rated load) is More efficient
65
Supercharging is the process of supplying the intake air to the engine cylinder at a density _________ the density of the surrounding atmosphere.
Discuss
Answer & Solution
Answer: Option C
Solution:
Supercharging is the process of supplying the intake air to the engine cylinder at a density Greater than the density of the surrounding atmosphere.
66
Air fuel ratio at which a petrol engine cannot work is
Discuss
Answer & Solution
Answer: Option D
Solution:
Air fuel ratio at which a petrol engine cannot work is 20 : 1 and less
67
In a four-stroke petrol engine (actual cycle), the expansion stroke starts and ends approximately at:
Discuss
Answer & Solution
Answer: Option B
Solution:
In actual (practical) petrol engines, combustion is initiated by advancing the ignition so that the pressure rise occurs around the time of TDC; as a result, the effective expansion (power) action on the piston begins a few degrees after TDC rather than exactly at TDC.

Therefore, the idea that the expansion starts about 30° after TDC is used to represent the practical situation where maximum useful pressure is developed slightly after TDC.

However, strictly speaking, the expansion ends near BDC. In practice the exhaust-valve timing causes gas release somewhat before or around BDC (typical exhaust valve events are tens of degrees before BDC), so any statement placing the end of expansion many degrees after BDC is imprecise.

Summary: Option C is the choice intended to represent the practical/start-after-TDC behaviour of the power stroke, but note that the exact end of expansion is actually around BDC (with valve events occurring slightly before BDC) rather than 50° after BDC — the key point is that the power stroke begins after TDC in real engines.
68
The volumetric efficiency of a well designed engine may be
Discuss
Answer & Solution
Answer: Option D
Solution:
The volumetric efficiency of a well designed engine may be 75 to 90%
69
Compression loss in I.C engines occurs due to
Discuss
Answer & Solution
Answer: Option D
Solution:
Compression loss in I.C engines occurs due to
- Leaking piston rings
- Use of thick head gasket
- Clogged air inlet slots
70
The reference fuels for knock rating of spark ignition engines would include
Discuss
Answer & Solution
Answer: Option D
Solution:
The reference fuels for knock rating of spark ignition engines would include Normal heptane and iso-octane