A fuel injection system which is generally used in diesel engines and forces fuel directly into the combustion chamber. It requires very high injection system pressure to overcome the pressure within the combustion chamber

Fuel-injection system employing a fuel delivery nozzle inside each combustion chamber.

where fuel is injected directly into the (main) cylinders of an engine, esp' in diesels or very rarely in petrol engines; more efficient than indirect injection where diesel is injected into a small chamber off the main cylinder.

In diesel engines with direct injection the combustion chamber is not divided and fuel is injected directly to the cylinder.

Engine system where petrol or diesel is injected directly into the engine cylinder instead of in a pre-combustion chamber or manifold. Direct injection provides more efficient combustion with lower consumption and gas emissions.