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  F7     F9




  Diesel Engine 1

Chemical energy
High efficiency
Few pollutants
Mechanical energy

The diesel engine's task is to convert the chemical energy, embedded in a very ignition-willing fuel, as efficiently as possible and with few emissions into mechanical energy.

Fuel consumptionPollutants
Life span
especially on
short distances

Pure air is sucked in. Without supercharging a minimum compression of 18 : 1 is necessary for the combustion. (approx. 30 bar) The fuel is injected into the heated air. This takes place with a nozzle opening pressure of around 130 bars for the outdated side combustion chamber process, making use of the modern direct injection method substantially higher pressures are in place. Without electric ignition system the combustion occurs immediately (self-ignition). The injection pressure is generated by a mechanical high-pressure pump and through nozzles, reaches the combustion chamber.

Development stages (passenger cars)
Common Rail
(replaces all other methods)
Adjustable charger

Petrolcompared withDiesel + 13%

In contrast to the petrol engine there is always more than enough air in all operational stages, also without supercharging. Therefore, and because of the high temperatures nitrogen oxides (NOX) tent to develop more easily. The shorter mixture formation and the approx. 13% higher C concentration in the diesel fuel in comparison to petrol fuel raises also the ejection of soot (particles). The diesel engine stands at the beginning of its exhaust gas cleaning program, the petrol-driven cars surpassed this stage already.

Combustion proceduresSystem pressureEfficiency
Direct-injectionPiston chamber450 - 2.200 barUp to 48%
Side combustion chamber
Pre-ignition chamberUp to 450 bar20 - 38%
Swirl chamber

Subaru produces the diesel as a boxer engine