Question

For which operation is the Lean air-fuel mixture required?

(a) Starting

(b) Idling

(c) Cruising

(d) Acceleration

I got this question during an interview.

I need to ask this question from Petrol Engine Fuel Supply System topic in section Petrol Engine Fuel Supply System of Automotive Engine Design

Answer 1

Correct answer is (c) Cruising

For explanation I would say: During cruising the air-fuel mixture is lean as the emission is controlled by using this ratio. Where more air is burnt for the same value of the fuel when operating at sea level. These weaker mixtures provide a good economy when compared to the economy of the rich mixture.