Question

Crankcase explosion in I.C. engine usually occurs as __________

(a) first a mild explosion followed by a big explosion

(b) first a big explosion followed by a mild explosion

(c) both mild and big explosions occur simultaneously

(d) never occurs

The question was asked during a job interview.

This interesting question is from Terminologies and Defintions topic in section Two Stroke Engines of IC Engine

Answer 1

The correct answer is:

(a) first a mild explosion followed by a big explosion

Crankcase explosions in two-stroke internal combustion engines typically occur in two stages. First, a mild explosion or backfire happens due to the ignition of unburned fuel-air mixture in the crankcase. This is followed by a big explosion when the pressure from the initial ignition triggers a larger explosion due to a more substantial buildup of pressure and fuel. This phenomenon is often caused by improper fueling, excessive oil, or faulty ignition timing.