An internal combustion engine in which fuel is ignited entirely by compression of the air supplied for combustion is called what?

• A. Gasoline Engine
• B. Diesel Engine
• C. Spark-Ignition Engine
• D. Turbine Engine

Answer: (B)

Compression ignition is the defining idea. In a diesel engine, air is highly compressed to raise its temperature, then fuel is injected into that hot, high-pressure air and auto-ignites without a spark. This is different from spark-ignition engines, which rely on a spark plug to ignite a premixed air-fuel mixture. A turbine engine isn’t a piston internal-combustion engine and relies on continuous combustion in a turbine rather than compression-ignition in a cylinder. So the engine described—fuel ignited solely by the compression of the intake air—is a diesel engine.