Common Rail Diesel Engines

Common rail refers to a long metal cylinder, and it defines the fuel injection system used for engines. Common rail diesel engines are good examples of modern diesel technology. They are composed of the injection pump, rail injectors, sensors, and an electronic control unit that detects the operating condition of the engine. There are many forms of diesel fuel injectors, but the common rail is becoming more popular. It uses high pressure to deliver fuel as opposed to the traditional direct fuel injection system of using low pressure to produce fuel. The rail receives fuel from the pump and distributes it to the injectors. You can check out common rail injection tester to purchase your engine or any other related product. We discuss the good and bad factors of a common rail diesel engine.

Advantages of a common rail diesel engine

  • Flexibility.

The fuel pressure is not dependant on the engine speed and load conditions; therefore, the fuel injection quantity and timing are easily controlled. It is also what differentiates common rail systems from other injection systems, whereby pressure increases with engine speed. Also, torque is usually low when the engine speed is low.

  • More power output

Vehicles with a common rail diesel engine produce higher horsepower, approximately 25% more than the traditional diesel engines displacing the same amount of fuel. Due to this, its performance is generally improved.

  • Quieter performance and fewer vibrations

The noise quality is improved as the multiple injections reduce combustion noise. The overall driving experience becomes better since the vibrations are also reduced.

  • Reduced amount of emissions

The engine was developed out of necessity. The main reason as to why this type of engine was developed is that regulations were made to curb carbon emissions. The common rail diesel engine records a reduction in the black smoke caused by incomplete combustion at low engine speed, thus making it environmentally friendly and safe for people.

  • Better fuel mileage

The common rail engine consumes a low amount of fuel compared to the traditional ones. They provide great mileage; thus, you can drive more miles and make fewer stops at gas stations.

Disadvantages of a common rail diesel engine

  • High vehicle cost

The price of the car is high as this is a more advanced type of diesel engine and has a high-pressure pump. Since the engine comes with the car, its price is reflected in the overall amount of the car. For a personal vehicle, you have to consider if the general cost is worth it.

  • Expensive parts

With the sophisticated engine, if it malfunctions or has any defective component, it will cost you more money to fix or replace it as the parts are quite expensive.

  • Requires more maintenance

The engine has to be regularly maintained as it needs more maintenance than traditional diesel engines. If you plan on doing the maintenance yourself, it will take you more time, effort, and expense.

  • Highly susceptible to damage

If proper care is not followed, the engine is likely to get destroyed, because the higher the injection pressure, the tighter the tolerances have to be. These tolerances make the surfaces very vulnerable to anything that is not fuel.


Advancement in diesel technology is of great benefit to the automotive industry. The common rail diesel engine has many pros compared to its cons; thus, most people are slowly moving towards that direction do to the advantages.


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