gas engine vs diesel engine

When buying a car, many people will wonder how to decide between a diesel engine vs gas engine, since it all depends on personal needs. Also, considering the importance of the model we like or the brand we like, and the prices we can afford, the type of engine is critical as it will determine maintenance costs and the type of fuel we need, among other things.

Today we are going to investigate a little more to try to explain the differences in performance between a diesel engine vs gas engine.




The Difference Between a Diesel Engine Vs Gas Engine

To understand the difference between a diesel engine vs gas engine, you need to understand how an internal combustion engine works.

  • Briefly explained, the operation of the engine consists of four steps:
  • The valve admits the mixture of air and gasoline.
  • The piston compresses the fuel.
  • Combustion of fuel occurs.
  • The second valve evacuates the gasses burned by combustion.

The main difference between a diesel engine vs gas engine is in the third stage. In a gasoline engine, the spark plug creates a flame that causes combustion, while in a diesel engine, combustion occurs solely from the pressure of the piston on the fuel.

This is the main difference between a diesel engine vs gas engine, and several characteristics of these engines are derived from it, which ultimately determine the advantages and disadvantages of gasoline engines and diesel engines.

What Exactly Happens When You Press the Accelerator Pedal?

In this case, the answer is simple; the diesel engine changes power by changing the ratio of air and fuel entering the combustion chamber. Pressing the accelerator pedal will increase the amount of diesel fuel flowing through the nozzles, which means that more diesel fuel in the air creates more power.

In the case of a gasoline engine, its operation is a little more difficult to understand since we introduce a concept that is not found in a diesel engine, the throttle body. The throttle body is basically a valve that turns airflow on and off to the engine. When we step on the accelerator, we only act on this valve, which increases the amount of air that enters the combustion chamber.

Diesel Engine Vs Gas Engine: The Engine Brake

One difference worth explaining is how the engine causes the vehicle to brake, which is done differently in a diesel engine vs gas engine.

In the case of a gasoline engine, the engine brake is caused by the intake system (not to be confused with the engine brake that we apply to the gearbox).

When we let go of the accelerator pedal, the throttle valve shuts off the airflow, preventing air from entering the combustion chamber and creating a vacuum. The force required by the piston to create a vacuum is the energy gained from braking.

For diesel cars, since they do not have a throttle, it is not possible to shut off the airflow to create this vacuum. The natural process is as follows: the valve opens, air enters, the valve closes, the air is compressed, and when the piston reaches top dead center, it begins to descend under the pressure of the compressed air. In this way, there is almost no power loss.

To counteract the force of compressed air on the piston without pressing on the accelerator pedal, the exhaust valve opens as the piston descends, allowing stagnant compressed air to escape and counteract the force it exerts on the piston.




Are Diesel Engines Reliable?

Since the diesel engine uses a compression ignition, it has a lot of resistance. They used to be heavy, but with modern manufacturing methods their weight has been greatly reduced and they are now almost equal to gasoline engines.
A diesel engine is also simpler because it does not have spark plugs or the electrical system associated with them. In general, diesel engines tend to last longer than gasoline engines in terms of kilometers or hours before an inspection is required, so repairs are cheaper and farther away.

Advantages And Disadvantages of Diesel Engine Vs Gas Engine

One of the main advantages of gasoline cars over diesel is their price. They are generally cheaper. However, gasoline cars are cheaper to buy because diesel cars are cheaper in terms of fuel costs.

If driving long distances every day is the goal, it may be worth spending a little more on a diesel engine, since it uses 15 to 20 percent less fuel per fill than gasoline. However, diesel cars are more expensive to maintain. It is estimated that people spend between 20% and 25% more than with gasoline cars.

As we have already mentioned, the main disadvantage of diesel cars is the price. They are stronger and more technical, which is why they cost more. Vans are a clear example: the diesel version is more expensive, but at the same time cheaper.

On the other hand, these types of engines last longer than gasoline engines. Although some parts can be more expensive to maintain due to their technical complexity, there are no electrical components that need to be changed, so the most frequent service is limited to oil and filter changes.

Reasons To Buy a Diesel Car

Some of the arguments that can make buying a diesel car more attractive are that they consume less fuel and have more autonomy; continuous improvement of its power supply and controllability; and continuous improvement of its acoustic insulation. They have the best response at low revs, respond well to the accelerator, and the value of the fuel used is cheaper than gasoline.

Another advantage of these vehicles is that they emit fewer greenhouse gasses than gasoline. In other words, current diesel engines have catalytic converters and filters that significantly reduce polluting emissions from combustion residues. But gasoline cars have managed to develop and compete in this area. So, today it doesn’t make much sense to say that one is “cleaner” than the other.




Reasons To Buy a Gasoline Car

Some of the reasons why we should choose gasoline cars is that diesel cars consume less but are more expensive to maintain, usually more expensive than gasoline cars, and in many cases many kilometers have to be traveled to amortize their cost.

Diesel cars have multiple catalytic systems to reduce emissions and are expensive to replace if necessary. They fail under certain conditions, such as city use, as they cannot be regenerated and are expensive to replace.

If the vehicle is essentially for urban use, a gasoline engine is preferred, since the range is by definition shorter and the number of starts and stops is greater. If the optimum operating temperature is not reached, the diesel engine is affected and the life of its emission control system is significantly shortened.

On the financial front, diesel cars tend to be more expensive to insure and tax because the car is more expensive, while today’s gasoline engines offer modest cost savings.

You can find more information about these two types of engines on our site mecanicadiesel.org.

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