Question

The thermal efficiency of a petrol engine is ____________ as compared to diesel engine.

(a) same

(b) less

(c) more

(d) none of the mentioned

The question was posed to me in a job interview.

The above asked question is from Comparison of Two Stroke S.I. and C.I. Engines topic in portion Two Stroke Engines of IC Engine

Answer 1

The correct answer is:

b) less

The thermal efficiency of a petrol engine is typically less than that of a diesel engine. This is because diesel engines operate at a higher compression ratio and have a higher thermal efficiency, which allows them to extract more energy from fuel. Petrol engines, on the other hand, have lower compression ratios and therefore lower thermal efficiency. Additionally, diesel engines are more efficient in converting fuel energy into work due to the higher energy density of diesel fuel.