The clearance in the engine cylinder

Clearance in the engine cylinder is the volume left between the piston and the cylinder head when the piston is at top dead center.

This clearance is essential for mechanical reasons, such as preventing contact between piston and valves.

But increasing this clearance leads to:

✔ Lower Compression Ratio: More clearance means less compression, reducing engine power and efficiency.

✘ Mean Effective Pressure (MEP) does not increase: In fact, it decreases because the combustion gases expand over a larger volume with less pressure buildup.

✘ Work Done does not increase: With a lower pressure due to lower compression, the work output also drops.

✔ Overall, efficiency drops as more heat is wasted and less useful work is obtained.

Thus, only Option C is correct. Options A and B are incorrect, so D (All of these) is wrong.