It’s common on our street roads today to see vehicles carrying either petrol engines or diesel engines. these two types of automobile engines are the conventional types, even though one existed before the other.
Despite their widespread use, most drivers are unaware of the differences between gasoline and diesel engines. They work on different cycles. A gasoline engine uses the Otto cycle, while a diesel engine uses the diesel cycle.
In this reading, we’ll explore the differences between petrol and diesel engines. We’ll cover their advantages and disadvantages and find out which is the best.
Let’s begin!
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What is Petrol (Gasoline) Engine?
The petrol engine is an internal combustion engine that uses spark ignition to burn fuel. It runs on a relatively volatile fuel known as petrol.
In a petrol engine, the carburetor prepares the fuel and air mixture before it enters the combustion chamber as a gas. Therefore, they typically combine after compression.
Just as mentioned earlier, petrol engines work on the Otto cycle, which consists of two isochoric processes and two isentropic processes.
Finally, the existence of a spark plug in the petrol engine is very essential, as it’s the device that produces a spark so that the gas in the cylinder can explode. The engine ignition system is what powers this spark plug.
Advantages
Petrol (gasoline) engines have several advantages over diesel engines and other engine types. Here are some of the key benefits:
- Petrol engines are generally more powerful, by way of horsepower, than diesel.
- Petrol engines also typically benefit from being easier to tune.
- A gasoline engine, which is also known as a petrol engine, has a better ratio of cost to power and burns fuel more eco-friendly than diesel performs.
- Petrol is usually cheaper than diesel fuel.
Disadvantages
Petrol (gasoline) engines, while popular for their performance and cost advantages, have some disadvantages compared to other engine types like diesel or electric engines. Here are the key drawbacks:
- Petrol engine lifespan is almost always shorter than that of diesel.
- The engines get fewer miles per gallon (sometimes significantly) than their diesel counterparts.
Related: What Is A Petrol Engine, Its Application, Parts and How it Works?
What is Diesel Engine?
A diesel engine is an internal combustion engine, known as the compression-ignition engine. Rudolf Diesel was the one who filed for a patent on it.
Due to the fuel’s injection into the combustion chamber and subsequent ignition by the chamber’s hotter air, this engine operates quite differently from a gasoline engine.
This causes the elimination of the spark plug in the engine design. The higher temperature of the air in the cylinder is due to adiabatic compression. This engine only compresses the air, not the fuel.
When the diesel fuel is injected into the combustion chamber, it undergoes spontaneous ignition.
Advantages
Diesel engines have several advantages over other types of engines, especially gasoline engines. Here are some of the key benefits:
- It has the highest effective efficiency of all combustion engine
- The diesel engine can combust a huge variety of fuel
- The vehicle boasts low fuel costs. That is, it is economical.
- It has a high energy density
- Good lubrication properties
- Low risk of catching fire, as flammable vapor is not produced
- Injection of fuel directly into the combustion chamber has no intake of air restriction apart from the air filters.
- Diesel engines have excellent exhaust-emission behavior.
Disadvantages
Despite the numerous advantages, diesel engines also have some disadvantages compared to gasoline and other engine types. Here are the key drawbacks:
- The disadvantage of the petrol engine is that, generally, its lifespan is almost always shorter than that of the diesel.
- This practically relates to the fact that diesel engines will usually have a higher residual (resale) value.
- Gasoline engines get fewer miles per gallon (sometimes significantly) than their diesel counterparts.
Related: What Is Diesel Engine? Its Diagram, Applications and Parts
Difference Between Petrol and Diesel Engines
In general, the difference between petrol and diesel engines is not only due to the fuel they use. Many other factors distinguish the two engine types, such as the use of fuel injectors in diesel engines, which do not rely on spark plugs.
Now we get to understand that diesel engines are used in much heavier machinery, such as tractors, trucks, and buses. Whereas, petrol engines are used on lighter vehicles such as motorcycles, scooters, and cars.
Which one is better? Petrol or Diesel engine
This question is common among auto students and car enthusiasts but is entirely wrong. If one of the engines is better than the other, the two wouldn’t have been used in our community today.
A fact about petrol engines and diesel engines is that they are suitable for specific kinds of vehicles, even though diesel engines are now employed in commercial cars. Choosing the best of the two also depends on how and from where you are driving.
The benefits of these fuels may vary depending on the country’s usage regulations and compliance. Before the widespread use of the electric engine, gasoline engines were common on the road in the United States, before diesel engines began to gain popularity in the news.
However, diesel engines from specific companies have been detonated for their lack of obedience to U.S. emissions laws.
Diesel Engine |
Petrol Engine |
| Works on Diesel cycle | Works on Otto cycle |
| Fuel is mixed with air inside the cylinder | Air and fuel are mixed in a carburetor |
| Ignition is achieved with hot compression | Fuel is ignited with an electric spark plug |
| High initial and maintenance costs | Comparatively low initial cost and maintenance cost |
| Relatively low fuel consumption | The fuel consumption is high. |
| diesel fuels have low volatilities | Highly volatile fuels are used (gasoline) |
| Generally used in heavy vehicles such as trucks and buses | It is used in light vehicles such as motorcycles and cars. |
| High power production | Relatively low amounts of power are produced in Petrol engines |
| High compression ratio | Relatively low compression ratio |
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FAQs
Which engine life is better, petrol or diesel?
Cars powered by diesel and gasoline can, with regular maintenance, last about the same amount of time. On the other hand, diesel engines are known for their durability and longevity. However, with proper maintenance, modern petrol engines also boast durability and long-lasting performance.
Which lasts longer, petrol or diesel?
However, diesel engines last longer than gasoline engines. The reason is that diesel is a relatively light oil that, when burned, lubricates engine parts, making them last longer.
Which engine is more efficient?
Petrol does not undergo complete combustion; hence, there is some fuel wasted. For this reason, diesel engines outperform their gasoline counterparts.
Why is a diesel engine more efficient than a petrol engine?
Diesel fuel is more cost-effective since it contains more energy per gallon compared to gas fuel. Even though diesel engines are still more fuel efficient than gas engines, city drivers may find them inadequate.