How Do Diesel Engines Work?

Do you own a diesel car? Ever wondered how diesel engines work? Diesel engines are powerful and are used in the heavy duty machinery and transport vehicles including ships, submarines, trains and trucks. Although similar to petrol engines, diesel engines are capable of providing more power, efficiency and can work in more demanding applications. The following is a guide on diesel engines and how they work.

What Is A Diesel Engine?

A diesel engine is a form of an internal combustion engine where fuel is burnt inside the main cylinders where the power is produced. This type of engine is different to the external combustion engines which are used by old steam powered locomotives. Steam engines use a large fire at the end of the boiler which heats the water to make the steam that powers the engine. In this system the steam flows along lengthy tubes to the cylinders at the opposite end of the boiler. This steam pushes the pistons back and forth which causes the wheels to move. This is called an external combustion because the fire source is outside the main cylinders. In a diesel engine the fuel burns within the cylinders themselves. Because the heat doesn’t have to flow from elsewhere, internal combustion engines tend to waste less energy. This is why internal combustion engines are more reliable and efficient than external versions.

How Is A Diesel Engine Different From Gasoline Engines?

Both diesel and gasoline engines work by internal combustion, but in different ways. In gasoline engines the fuel is injected within the small metal cylinders. The mixture is compressed by pistons making it explosive. This causes it to set on fire when a spark from the spark plug is initiated. When the mixture explodes it causes power to generate which then pushes the piston down the cylinder, through the gears and crankshaft before turning the wheels.

Diesel engines on the other hand are similar in design but are much simpler in their operation. In diesel engines the air is brought within the cylinder before the piston compresses it, but in a more definite way than a gasoline engine. Gasoline engines tend to have their fuel and air mixture compressed but to a tenth of its original volume. Diesel engines on the other hand compress the mixture up to 25 times. Because of this compressing action it starts to heat up until the air becomes very hot usually anywhere up to 1000°F or 500°C. When the air is compressed, a fuel mist is then sprayed into the cylinder by an electronic fuel injection system. Because the air is very hot it causes instant ignition of the fuel and explodes without the need for a spark plug like a gasoline vehicle. This explosion causes the piston to push out of the cylinder producing sufficient power which helps to give the vehicle the drive it needs. When the piston goes within the cylinder, the gases from the exhaust are then pushed through the exhaust valve. This process continuously repeats thousands of times over a minute.

What Makes A Diesel Engine More Efficient Than Other Engines?

Diesel engines are said to be anywhere up to 40 percent more efficient than other types of engines. This means diesel engines have the ability to drive further on the same amount of fuel than gasoline vehicles. There’s a number of reasons why this is. The first reason is because there isn’t a need for spark plug ignition meaning the compressing of fuel is much simpler. The second is the amount of times the fuel/air mixture is compressed more than gasoline engine mixtures. This additional compression releases more power. Gasoline engines that don’t work at full power require additional fuel to help keep the cylinders working while diesel engines don’t have this issue. They use less fuel when working at a lower power. Because diesel fuel offers better lubrication, it helps to run the machine better with less friction.

How Is Diesel Fuel Different?

There is a big difference between diesel and gasoline fuel. Diesel is a less refined and lower grade petroleum product which is manufactured from heavier hydrocarbons. Hydrocarbons are the molecules which are built from more hydrogen and carbon atoms. Diesel engines which use crude diesel, lack the sophistication of fuel injector systems and therefore can run on almost any type of hydrocarbon fuel.

The Advantages And Disadvantages Of Diesel Engines

There are many different advantage and disadvantages of diesel engines in today’s world. Diesel engines tend to offer more versatility as a fuel burning engine and is found in larger machinery such as cranes, trains, submarines and bulldozers. Compared against gasoline engines, they are more efficient, simpler in design and tend to be more economical. They tend to offer more safety than gasoline engines because their fuel is less volatile and emits less explosive vapors.

Another advantage of the diesel engine is that they are better for moving larger load weights at slower speeds than gasoline engines. This makes them suitable for use in trucks, tractors, locomotives, and freight-hauling ships. Because they offer higher compression rates, they have to withstand larger strains and stresses than gasoline engine vehicles. This is why they are used in a large variety of machines over many years.

One of the disadvantages of a diesel engine is the pollution that it emits. They tend to be nosier than other engine types and can produce a lot more unburnt soot particles which can cause a hazard to your health.


Over the year’s diesel engines have become a reliable, powerful and efficient type of engine which has been used and still is in use in many vehicles right around the world. With the capacity to provide sufficient power in demanding load bearing applications, it’s no wonder the diesel engine is a popular choice for vehicle owners looking for more power for certain driving conditions and requirements. So are you looking to buy a new vehicle soon? Are you thinking about buying a diesel engine vehicle?

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