Why do Diesel engines have that distinctive sound to them when compared to gasoline engines?

Question

Why do Diesel engines have that distinctive sound to them when compared to gasoline engines?

In: 2497

Answer 1

Because they are igniting under knock conditions instead of under spark conditions. Knock ping is the noise you hear rather than a smooth expansion of the gasoline explosion. A gas engine makes a similar noise when not working correctly but usually it breaks shortly after. (Eli15 or so I guess)