Common rail

Diesel fuel injector as installed in a MAN V8 Diesel engine Common rail direct fuel injection is a direct fuel injection system built around a high-pressure fuel rail feeding solenoid valves. This pressure is typically over 2,000 bar or 200 MPa or 29,000 psi. A common rail system contrasts with the low-pressure fuel pump feeding unit injectors (or pump nozzles). High-pressure injection delivers power and fuel consumption benefits over earlier lower pressure fuel injection, by injecting fuel as a larger number of smaller droplets, giving a much higher ratio of surface area to volume. This provides improved vaporization from the surface of the fuel droplets, and so more efficient combining of atmospheric oxygen with vaporized fuel delivering more complete combustion.

Common rail injection is widely used in diesel engines. It is also the basis of gasoline direct injection systems used on petrol engines.