Question

The surface of the exhaust manifold is made smooth to minimize the restriction of what?

(a) Exhaust gas

(b) Temperature

(c) Heat

(d) Contraction

I had been asked this question in an interview for job.

My doubt stems from Intake System topic in section Fuels, Intake System & Leakage Preventers of Automotive Engine Design

Answer 1

Right answer is (a) Exhaust gas

To explain: Rough interior surfaces of the manifold runners will increase resistance to the mixture flow and the surface of the exhaust manifold is made smooth to minimize the restriction of exhaust gas.