Terminology check — what are petrol engines commonly called? Petrol fueled reciprocating engines initiate combustion with an electric spark from a spark plug. These engines are commonly known as:

Introduction / Context:
Engine classification is often based on the method of combustion initiation. Petrol engines rely on premixed charge ignition triggered by an electrical spark, whereas diesel engines depend on auto-ignition from high compression temperatures.

Given Data / Assumptions:

• Petrol-type fuel and a throttle-controlled intake.
• Presence of spark plugs and ignition system.
• Standard four-stroke or two-stroke SI operation.

Concept / Approach:
Spark ignition engines initiate combustion using a timed spark to ignite an air-fuel mixture prepared by a carburetor or fuel injection. The idealized thermodynamic model is the Otto cycle with constant-volume heat addition. Compression ignition engines, on the other hand, inject fuel into hot compressed air and rely on auto-ignition, not a spark.

Step-by-Step Solution:
Identify combustion trigger: electrical spark for petrol engines.Relate to standard terminology: spark ignition (SI).Therefore, petrol engines are commonly called spark ignition engines.

Verification / Alternative check:
Technical literature abbreviates petrol engines as SI and diesel engines as CI, confirming the accepted naming convention.

Why Other Options Are Wrong:
Compression ignition refers to diesels. Detonation control and auto-ignition engines are not standard classification terms for petrol engines.

Common Pitfalls:
Assuming that the presence of occasional knock in petrol engines implies compression ignition; it does not. Normal operation is spark initiated.

Final Answer:
Spark ignition engines