The diesel engine is often is called a/an _______ ignition engine

• A. Spark ignition
• B. Compression
• C. Catalytic ignition
• D. Electrical ignition

Answer: (B)

Diesel engines use compression ignition. In the cylinder, air is compressed to a very high pressure, which raises its temperature enough that when fuel is injected it auto-ignites without needing a spark. This is different from spark ignition, used in gasoline engines, where a spark plug ignites a premixed air–fuel mixture. Catalytic ignition isn’t a method used to start combustion in engines, and electrical ignition isn’t the ignition method for diesels (though glow plugs may assist starting in cold conditions).