Question

Which of the following engines will have heavier flywheel than the remaining ones?

(a) 30 kW four stroke petrol engine running at 1500 r.p.m

(b) 30 kW two stroke petrol engine running at 1500 r.p.m

(c) 30 kW two stroke diesel engine running at 750 r.p.m

(d) 30 kW four stroke diesel engine running at 750 r.p.m

I had been asked this question during an online interview.

Question is from Disadvantages of Two Stroke Engines in portion Two Stroke Engines of IC Engine

Answer 1

Answer: (c) 30 kW two stroke diesel engine running at 750 r.p.m

Explanation:

In a two-stroke engine, the power output is delivered every revolution of the crankshaft, as opposed to a four-stroke engine, which delivers power every other revolution. This leads to a less uniform turning moment (torque) in two-stroke engines, requiring a heavier flywheel to smooth out the power pulses.

In this question, a 30 kW two-stroke diesel engine running at 750 r.p.m would have the heaviest flywheel. The lower engine speed (750 rpm) means that the power pulses are further apart, and a heavier flywheel is needed to maintain smooth operation and reduce vibrations. Additionally, diesel engines generally require heavier flywheels compared to petrol engines, due to their higher torque characteristics.

Thus, option (c) is correct.