Difference Between Gasoline Engines and Diesel Engines

Gasoline engines vs diesel engines

One of the prevailing confusion among car buyers is the difference between gasoline engine and diesel engine. Perhaps the common knowledge or perception is that diesel engines are noisier and their vibration is intolerable, while gasoline engines run smoothly. Well, this is not far from the truth, however. But, with modern engine technology, diesel engines are more competitive than before, so we have cars that run efficiently, and we also have increasing popularity and demand.

Gasoline and diesel engines are the most popular internal combustion engines used primarily in modern vehicles, and diesel is also widely used in the construction industry to handle heavy loads. Let’s unfold the differences between these engines. Let’s start with how they work.

How do gasoline and diesel engines work?

Apparently these engines work the same with the difference noted in the way they ignite the fuel. They use the same 4-stroke: a series of steps including intake, compression, combustion/power, and exhaust. The main purpose is to convert the chemical energy in respective fuels into mechanical energy so that the car wheel is activated.

Gasoline engine

In a bit of history, the gasoline engine was invented in 1876 by Nikolaus August Otto . This explains why the gasoline engine is said to work on the Otto cycle, which is a 4-stroke combustion cycle. Other engines came in after this invention intended to improve their efficiency. Further evaluation of the gasoline engine revealed that about 10% of the fuel was being used, while the rest was lost to unnecessary heat production. But since then, modern technologies have played a critical role in revolutionizing the way gasoline works.

Gasoline engines use the electrical spark to ignite the fuel-air mixture in the combustion chamber. There is a piston in linear motion; which is going down and up when prompted. When it goes down it sucks in air and fuel is also added at the same time to create a smooth mixture in the carb before going to the cylinder. Gasoline is highly volatile and evaporates than diesel. That is why it is easy to mix it with the air.

The piston will then move up to compress the air-fuel mixture in the cylinder. That compression will make the mixture warmer, but not hot enough for self-ignition, as is the case with diesel. If this is the case, the mixture can spontaneously react and cause engine knock, which will damage engine components.

To ignite the mixture during piston movement, the spark plug is used. The mixture will burn very quickly by turning the liquid mixture into a gas. The power stroke results in where the increased volume allows the piston to force down. As you go up, the open valves will make way for the exhaust. The process continues like this for gasoline engines, including those with in-cylinder gasoline direct injection technology. The 4-stroke combustion cycle of the gasoline engine is described below:

  • Intake Stroke – Fuel mixes with air in the carburetor.
  • Compression stroke – the fuel and air mixture is compressed as the piston moves up in the cylinder
  • Ignition Knock – The spark plug is used to ignite the fuel-air mixture.
  • Exhaust stroke – the piston will push the exhaust out through the exhaust valve

Motor diesel

Two years after the invention of the gasoline engine, Rudolf Diesel, while attending an engineering school in Germany in 1878, learned about the low efficiency of the gasoline engine and was later inspired to invent a powerful competitor: the diesel engine. to provide higher efficiency. Regarding the combustion power. The diesel engine was patented in 1892.

Unlike the gasoline engine, the diesel engine does not rely on the spark plug to ignite its fuel. What it does is rely on high pressure compression to make the explosion. There is still a movement of the gun in the motor where it sucks in the air to be compressed. When it goes up, the piston compresses the air using a higher compression ratio ranging from 14:1 to 25:1 compared to the 8:1 to 12:1 compression ratio of the gasoline engine.

If the engine has a turbocharger, it will draw more air into the cylinder and exert more pressure. The heat in the cylinder can reach very high temperatures. The fuel injector will inject diesel fuel just in time, and it will start to burn as a result of the high air temperature and pressure in the cylinder. This combustion will then produce a huge amount of gas that will keep the wheels moving. The diesel engine is also using the 4 stroke combustion cycle as described below:

  • Intake Stroke – The intake valve lets in air when the piston moves down.
  • Compression stroke – because the piston continues to move up and down, it will conduct the compression stroke when it goes up
  • Combustion stroke – the fuel will be injected to be ignited by the high temperature and pressure, which also forces the piston down
  • Exhaust stroke – when the piston goes back up, it lets the exhaust out through the exhaust valve

Key differences between these two engines.

To better understand these differences clearly, we need to consider certain aspects such as combustion, fuel efficiency, ecological compatibility, engine power/speed, and costs. Gasoline fuel, not the engine, is inevitably expensive, but avid car lovers continue to buy gasoline engines. Why is that? That has to do with the advantages of the gasoline engine over the diesel. Similarly, diesel is perceived as slow and noisy, yet some people, particularly the construction and agriculture industries, continue to rely on it. That also takes into account the advantages that outweigh the disadvantages.


The first difference is seen in the way combustion is running between these two engines. As already noted, combustion is ignited by the spark plug in a gasoline engine, while high compressed air ignites the fuel in a diesel engine. Diesel tends to have a higher compression ratio and that gives it more torque and the ability to haul heavy loads.

Due to the higher compression ratio, the diesel engine needs more robust engine components. That’s why it has heavy components. This explains why it is not favorably used in airplanes and racing cars because it can compromise their intended speed. The diesel engine is, however, widely used in buses, trains, ships and trucks for the need for high power in these vehicles.

On the other hand, the gasoline engine has a low compression ratio. This can be attributed to the volatility of gasoline fuel when mixed with air because it can cause engine knock, which can eventually damage the engine. The low compression ratio does not require heavy engine components. As a result of this, the gasoline engine is often found in light cars for its great power and speed.

fuel efficiency

Regarding fuel efficiency, cars that are powered by a diesel engine are more fuel efficient. Gasoline evaporates more and releases energy quickly. For this reason, you will have many trips to the gas station, and on top of that, gasoline fuel is expensive.

In general, diesel engines have higher mileage than gasoline engines, especially for long distances. Also, its fuel is cheaper, so you will save more even though diesel cars are relatively more expensive than gasoline cars.


Gasoline engines are not often maintained, but they do not last. Gasoline reduces lubrication, so engine components wear faster. The service life of the diesel engine is almost twice that of the gasoline engine. Diesel engines also don’t need frequent maintenance, but you do need to frequently replace oils and filters; Otherwise, the motor could be damaged. Diesel engine maintenance is more expensive than gasoline engine.

Performance and speed

The diesel engine works best where power is needed due to its increased torque. So to load heavy machinery on your vehicle, you need a diesel engine. But it lacks when it comes to speed. Gasoline engines outperform diesel engines with speed due to their higher power. They are light, so gasoline cars will run faster. But gasoline engines aren’t ideal for loading heavy machinery into your vehicle.

Diesel engines can have a starting problem when the engine is too cold to ignite the fuel. In such cases, the glow plug is used as an electrically heated wire to heat the combustion chamber so that self-ignition can be initiated at higher temperatures. But modern technology has brought computer controls in which the engine is controlled by the ECM, which communicates with sensors that are aimed at solving the ambient temperature problem to improve engine self-ignition. But small engines still rely primarily on the glow plug.


Unlike gasoline engines, diesel engines emit less carbon monoxide/carbon dioxide into the environment, although the burning of diesel is more visible than that of gasoline. But the negative side of diesel is the emission of large amounts of nitrogen compounds that can affect your health.

price matters

Diesel fuel (C 14 H 30 ), evaporates slowly because it is not volatile. It is also easily refined to a gasoline fuel ( C9H20 ) . This explains why diesel is so much cheaper than gasoline. However, the same cannot be said for the diesel engine and the gasoline engine. The diesel engine is expensive to purchase and maintain compared to the gasoline engine. Even buying the diesel car will break your bank. However, the difference can be recovered from a gas station because diesel fuel does not run out faster and is cheaper.

Can I put diesel fuel in the gasoline engine and vice versa?

This may be a common question asked by many people concerned about the difference between these engines. Diesel is less volatile, so it won’t react with air as much as gasoline does. The spark applied to a lean mixture will not even succeed in forming combustion.

As for the gasoline in the diesel engine, it may result in detonation due to its high volatility under the high compression ratio of the diesel engine. The engine could be severely damaged. Also, gasoline does not have lubricating properties, so engine components can wear out, leading to costly maintenance.

Tabular comparison between diesel engine and gasoline engine

Motor diesel Gasoline engine
Works in diesel cycle. Works in otto cycle.
The air is compressed and the fuel injector is used to spray fuel for self-ignition combustion. Fuel and air mixture in the carburetor and ignited by the spark plug.
High compression ratio and high torque Low compression ratio and low torque
More fuel efficient less fuel consumption
It is nonvolatile, evaporates more slowly, and has a high flash point. Volatile, evaporates faster and has a low flash point.
Heavy weight, used in heavy machinery and heavy vehicles such as buses, ships, and trucks. Lightweight, as used in light cars such as sports cars, motorcycles and airplanes.
It is expensive to maintain but is durable. Less expensive to maintain but doesn’t last.
It can carry heavy loads due to its high power density. Not suitable for carrying heavy loads due to lower power density
cheaper diesel fuel Expensive gasoline fuel
expensive diesel cars Affordable Gas Cars


The choice of any internal combustion engine between gasoline and diesel is purely a personal preference. It depends on the use of the car. If you want to enjoy racing sports, go for gasoline engines. Very light and high speed. The car is cheap compared to the diesel car. But the diesel car is more powerful especially in heavy loads. Diesel fuel and the diesel engine are indispensable in the economy because the construction industry and agriculture could suffer tremendously in their absence.

To involve!

Diesel engine and gasoline engines are often called combustion ignition engines and spark ignition engines. These are the most popular internal combustion engines. We saw how different they are, particularly in fuel firing, as well as other aspects such as fuel economy, environmental effects, speed and power, and maintenance costs.

Regardless of the difference, they use the same 4-stroke combustion cycle with the Otto cycle of a gasoline engine and the diesel engine, the diesel cycle. The difference is, as mentioned above, the ignition of the fuel because the gasoline engine uses spark plugs, while the diesel engine only uses high compression for self-ignition.

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