Pre-chambers

Older diesel engines have so-called pre-chambers. These pre-chambers are mounted in the cylinder head where the fuel is then injected before continuing towards the cylinder. The pre-chamber is also called the swirl chamber.

The shape of the pre-chamber creates a vortex of fuel resulting in a better air/fuel ratio. Pre-combustion also takes place in the pre-chamber, providing a preliminary ignition of the main mixture in the combustion chamber. This produces gradual combustion, resulting in a pre-chambered diesel engine with a less hard diesel knock than directly injected diesels (and therefore without pre-chamber).