What is a major distinction between diesel and gasoline engines?

The major distinction between diesel and gasoline engines lies in their combustion process, specifically how they ignite the fuel. Diesel engines operate using compression ignition, which means they compress the air within the cylinder to a level that raises its temperature significantly. When diesel fuel is injected into this high-temperature and high-pressure environment, it ignites spontaneously without the need for a spark plug. This method of ignition is what primarily differentiates diesel engines from gasoline engines, which use spark ignition to ignite a mixture of air and fuel.

This difference in ignition types directly impacts the performance and efficiency characteristics of the engines. Diesel engines typically offer higher torque and better fuel economy because they can operate at higher compression ratios compared to gasoline engines. Understanding this fundamental principle of how diesel engines operate provides valuable insight into their design and performance aspects, making it a crucial point of knowledge in engine repair and maintenance.