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The difference between a diesel engine and a gasoline engine

The difference between a diesel engine and a gasoline engine

Car enthusiasts, when choosing a car, look first of all at the capabilities of the engine and its characteristics. Doubts often arise when choosing between a gasoline and diesel engine. It is impossible to say exactly which one is better, because there are differences between them, and a choice must be made based on them. The success of the choice will depend on their strengths and weaknesses. What can be tolerated and what is unacceptable for the conditions of the roads on which they will drive. We will try to talk about all the nuances of these two devices.

Differences in device operation

The design of both engines is identical. Each of them has connecting rods, cylinders and pistons. But in order for a diesel engine to withstand serious loads, it has reinforced valves, so it has large dimensions and also weighs heavier than its gasoline counterpart. Its design is much more complex, and this affects the cost of the car.

The main difference between a diesel engine and a gasoline engine is their fuel. One runs on diesel fuel, and the other on gasoline, which is what their names imply. It is worth considering that gasoline is a highly flammable substance. A diesel engine is safer.

The formation of the fuel-air mixture occurs in different ways. What affects the operation of motors. In a diesel engine, air is first introduced into the cylinder. It heats up when the piston moves upward, the temperature can reach 900 degrees due to a decrease in air volume and an increase in its pressure, sometimes reaching 5 MPa. Then fuel under pressure enters through the nozzles, which immediately ignites from the hot air. As it expands, it causes a sharp increase in pressure in the cylinder, which is why the diesel engine is noisy.

The injection timing and fuel quantity are adjusted by the high-pressure fuel pump (HPFP), the main component of a diesel engine. Due to high-pressure injection, diesel is undemanding to fuel volatility, so it runs even on low-grade oils. The power of the unit is regulated by the fuel supply and because of this, even at low speeds the pressure does not drop. A car with such an engine can gain more power already at 2000 rpm, but a gasoline car is not so fast.

In a gasoline engine, the fuel mixture is formed directly in the intake system and is ignited in the cylinder by a spark from the spark plugs. Power control is carried out using air flow, which is dosed by the throttle valve. The start of a car with such an engine is less powerful, since its fuel pump cannot produce such high pressure as that of its diesel counterpart.

Engine power and performance

The diesel unit is superior to the gasoline unit in terms of efficiency. Although the price of diesel fuel has now been raised, it is still cheaper than gasoline. And we must also take into account that diesel engines consume less fuel than their gasoline counterparts. Now all European diesel cars have a Common Rail fuel system. It involves the installation of sensors that transmit information to the control unit and, based on it, the computer determines the fuel supply time and its quantity. It is noteworthy that the dose is calculated with milligram accuracy. This dosing ensures a smooth increase in pressure, and the engine runs without jerking when changing gears. With this system, fuel consumption decreased by 20% and low-speed torque increased by 25%. Therefore, diesel units have 40% more efficiency than analog units. That is, the combustion of fuel inside their devices is more efficient compared to gasoline models. Although there are also economical gasoline units.

Gasoline engines, of course, have more power, but diesel units compensate for this with smooth thrust at any speed, something their counterparts still need to strive for.

Produced noise and emissions

Diesel units are noisier and their operation is accompanied by vibration. And all due to the fact that the pressure in the combustion chamber is very high. But this is not so noticeable in the car interior if it has good sound insulation. At idle, the engine sounds like a rumbling sound and is therefore not irritating to the ears.

In European countries, the popularity of diesel engines is constantly growing. This is explained not only by economical fuel consumption, but also by their environmental friendliness. Their exhausts contain less carbon monoxide than gasoline-powered units.

Operational Features

Diesel engines are more durable and differ in their reliability from their gasoline counterparts. This is due to the design of the cylinder block and the thoughtfulness of the fuel system. Their parts, such as the crankshaft, head, cylinders, and injectors, are made of durable materials that prevent rapid wear. Diesel fuel also saves them from failure, since it performs two functions: it serves as fuel and lubricant. But here, we must take into account that this will be influenced by its quality, and, as you know, domestic diesel fuel includes various impurities. They can cause a reduction in the life of a diesel engine, although even with this nuance its performance will be higher than that of its gasoline counterparts. The latter react less sensitively to the quality of the fuel, and therefore withstand impurities and other inclusions that are found in low-quality gasoline.

Diesel engines react poorly to low temperatures; for their normal operation it is necessary to provide special winter fuel or install modern heating systems. Also, most diesel engines are equipped with glow plugs to facilitate starting the engine in cold weather, because diesel fuel is reluctant to evaporate at low air temperatures. They are a regular heating resistor. Basically, spark plugs are installed in the engine cylinders; after turning the key in the ignition switch, they turn on and, as soon as fuel enters the combustion chamber, they heat it to the temperature at which it begins to evaporate. After starting the engine, the spark plugs work for up to several minutes to reduce harmful emissions and stabilize the combustion process on a cold engine.

Another option could be an additive - antigel. It is poured into the fuel at every refueling, and it prevents it from curdling. Gasoline engines do not need this. But diesel engines do not react to water at all. They use electricity only to start the engine. Therefore, they are often installed on military vehicles and SUVs.

Maintenance of diesel and gasoline engines

The frequency of repairs and inspections is influenced by many nuances: vehicle operating conditions, climate, fuel quality, vehicle condition and part material. Repairing a diesel unit is more labor-intensive, since its design has its own characteristics. Its most expensive part is the fuel injection pump. But since diesel engine repairs occur much less frequently than gasoline ones, this will not hit your pocket hard. If you use the latter, you will need to constantly lubricate its parts so that they do not wear out.

Advantages and disadvantages of gasoline and diesel engines

First, let's look at the negative aspects of each of these motors. They are not so critical, but when considering the characteristics of engines they must be taken into account.

Disadvantages of a diesel engine:

  • sensitivity to fuel quality;
  • small number of diesel engine maintenance services. But this is rather not its drawback, but the lack of specialists in its repair in the country
  • as a result, the high cost of repair work
  • in winter, if you do not follow the operating recommendations, it may be difficult to start the engine and operate it. But high-quality fuel can ensure engine operation even at –55 0 C
  • does not always withstand high speeds and high revs
  • increased noise and vibration;
  • large engine dimensions;
  • low power
  • it has low operating speed limits (the maximum value is 4500), while a gasoline engine has average values from 3000 to 7000.

Disadvantages of a gasoline engine:

  • harmful carbon monoxide emissions
  • less durable compared to its diesel counterpart
  • high fuel consumption
  • its fuel is explosive
  • breakdowns of its parts are more frequent.

Now let's move on to the positive aspects of each of them. The advantages will demonstrate what the selected unit can provide, what functions it performs perfectly.

Advantages of a diesel engine:

  • environmental friendliness, its exhaust contains less carbon monoxide
  • diesel fuel is safer than gasoline;
  • more effective off-road;
  • has high traction forces at low speeds;
  • lower fuel consumption;
  • high efficiency;
  • there is no ignition system;
  • not afraid of dirt and water;
  • its fuel is used not only as fuel, but also acts as a lubricant;
  • lower cost of diesel fuel.

Advantages of a gasoline engine:

  • ease of manufacture and repair;
  • quiet operation;
  • high power;
  • high resistance to low-quality fuel;
  • responds well to low temperatures;
  • spare parts are affordable.

Having considered the features of design, operation, maintenance, power and performance, we can conclude that each of these two engines is good in its own way. By purchasing a more expensive car with a diesel engine, you can save on diesel fuel in the future. When used correctly, it is more durable and, as a result, reliable.

Looking ahead to the future, the future clearly belongs to environmentally friendly cars, which means that the demand for diesel engines will constantly increase. Gasoline is more powerful and simpler. There will be no problems with maintenance and repair, and spare parts for it are cheaper. Everyone chooses what they prefer on their own. You can accept advice, but the final decision is yours.


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