Question

In which of the following stroke concerning ultra-lean mode the fuel is injected?

(a) Intake

(b) Compression

(c) Expansion

(d) Exhaust

I had been asked this question by my college professor while I was bunking the class.

My question is taken from Petrol Injection topic in portion Petrol Engine Fuel Supply System of Automotive Engine Design

Answer 1

Correct answer is (b) Compression

To elaborate: In the ultra-lean mode the fuel is injected later on as the piston is moving up on its compression stroke. This forces the fuel-air charge right up to the spark plug points for the best burning condition. The combustion takes place partly in the cylinder and party in the shaped piston crown.