Difference Between A Petrol and A Diesel Engine - CMV360

Petrol and Diesel Engines are the two most commonly used engines in cars. Even though their usage seems similar, they have some differences and advantages over one other. Both the engines have basic four-strokes, intake, compression, power, and exhaust. The difference between them lies in the way both the fuels burn.

Gasoline or petrol evaporates, so it effectively mixes with the air. As a result, just a spark is enough to produce combustion in a petrol engine. On the other hand, diesel does not mix effectively with the air. In a gasoline engine, the fuel and air should be pre-mixed. In a diesel engine, however, mixing happens during the combustion itself. This is why diesel engines come with a fuel injector while petrol engines come with a spark plug.

Another thing to notice is that a petrol engine is less noisy as compared to a diesel engine. This is because the combustion process in a pre-mixed mixture is smooth, but in a diesel engine, the combustion can start anywhere in the combustion chamber and is an uncontrolled process. To reduce the excessive noise and vibration, diesel engines require a more rugged structural design than petrol engines. This is why petrol engines are preferred for lightweight cars. Diesel engines can achieve a good compression ratio without risk of self-ignition. A higher compression ratio leads to better efficiency. This is why diesel engines have better fuel economy than petrol engines.

Diesel engines give out smaller particulate than petrol engines. Older diesel engines are even worse when it comes to this. The modern type of diesel engines come fitted with particulate filters to help reduce the number of particulates that are being emitted in the environment.

Let’s look at the difference between a diesel and a petrol engine on the basis of their effect on the environment, popularity and price.

Effect on Environment - A petrol car will emit more carbon dioxide in comparison to a diesel car, and we all know that carbon dioxide is the greenhouse gas and it can cause climate change. However, while diesel may emit less co2 than a petrol engine, they produce more nitrogen dioxide and that can cause smog acid rain and respiratory problems in humans.

In other words, diesel is worse for the immediate health of people, and petrol is worse for the long-term health of the planet. For the protection against harmful nitrogen oxide emissions, certain cars use a system called AdBlue. AdBlue reacts in the cars exhaust system with the nitrogen oxide gases to produce harmless nitrogen and water vapour. You actually add this to a separate tank and it doesn't go in with the fuel. You'll probably have to top up the car once every couple of thousand miles. You can do that yourself or you could ask your franchise dealer to do it for you.

Popularity- The popularity of diesel cars has reduced in recent years. In 2011, the market share of diesel was 51 percent but now it has gone down to 44 percent. Over the past three months, the number of orders for diesel engine cars has dropped by 10 percent.

Price– A diesel car costs more than a petrol car. Now the price also depends on the brand, but generally, diesel costs more than the petrol engine.