Officer Aptitude Rating (OAR) PracticeTest

What are the four strokes of a 4-stroke engine?

1. Intake, combustion, exhaust, refuel

2. Compression, intake, exhaust, ignition

3. Intake, compression, combustion, exhaust

4. Intake, ignition, discharge, exhaust

The correct answer is: Intake, compression, combustion, exhaust

The four strokes of a 4-stroke engine are intake, compression, combustion, and exhaust. During the intake stroke, the engine draws in the air-fuel mixture through the intake valve as the piston moves down in the cylinder. Next, in the compression stroke, the piston moves back up, compressing the mixture, which prepares it for efficient combustion. This is followed by the combustion stroke, where the spark plug ignites the compressed air-fuel mixture, causing a powerful explosion that pushes the piston down, creating the power needed to turn the engine. Finally, in the exhaust stroke, the piston moves back up again to push out the spent gases through the opened exhaust valve, allowing the cycle to start anew. The correct answer encompasses the entire cycle of a 4-stroke engine and highlights the process of converting fuel into useful mechanical energy, which is central to the operation of internal combustion engines.