Petrol against diesel: What is the difference?
Several car manufacturers offer diesel-powered cars, but are they a good alternative?
Many of us have pulled up to the gas pump at our local convenience store, picked up the absent-minded nozzle at the end of the green hose and spent a few seconds of confusion wondering why it wouldn't fit into the car's fuel filler. We eventually realize [SJH1] it was the hose for diesel, not gasoline, and put it back on the holder.
However, we see that we see hoses at the gas pump [SJH2] wondering. What is the difference between a petrol engine and one that runs on diesel fuel, and why would anyone choose the other?
In fact, petrol and diesel engines have much in common. Both are internal combustion engines, and each converts chemical energy into fuel into mechanical energy. Both contain pistons that move up and down inside the cylinders, with the movement driven by the fuel combustion in each. These pistons are attached to a crankshaft, which turns when the pistons move to give the energy of the vehicle.
The difference between the two engines means how the fuel is lit. In the gasoline engine, the fuel is mixed with air in the cylinder. The flask compresses the mixture, which then ignites with a spark from the spark plug.
There is no spark plug in the diesel engine. Instead, it is the compression itself that ignites the air / fuel mixture, creating it containing the explosion that keeps the pistons moving.
Effect on performance
When most of us think of a diesel engine that comes to mind, [SJH3] are 18-wheelers we see on the interstate. Although it is true that these rigs run on diesel, there are many other diesel-powered vehicles on the road. They are not very common in the United States, but in Europe, more than one third of all cars are driven by diesel fuel.
The main advantages of a diesel engine compared to a petrol come in terms of fuel efficiency, engine reliability and power. Because diesel engines are built to withstand higher compression, they tend to be more reliable and longer than petrol engines. Diesel fuel is thicker than gasoline, and as such gives more power and mileage per gallon.
On the other hand, petrol engines are lighter and deliver higher performance than diesel engines. There are no diesel engines in sports cars for the same reason, there are no petrol engines in large trucks. In addition, petrol engines tend to be cheaper to repair simply because they are more common. [SJH4]
With all this in mind, what kind of engine is the best choice? The answer is that [SJH5] that with many things depends everything.
Years ago, diesel fuel was considerably cheaper than gasoline, but today the opposite tends to be true, which means that any savings in fuel costs are relatively less. Diesel engines tend to be more reliable than gasoline, but diesel-powered cars tend to cost more up front and repairs are likely to be more expensive. Conversely, petrol-powered cars are easier and cheaper to maintain and fuel efficiency is constantly improving.
Although diesel fuel used to be associated with black smoke which is cleared from the exhaust gas, today's diesel is relatively clean burning. Newer diesel-powered cars produce lower levels of carbon dioxide than gasoline-powered cars, but higher levels of particles and nitrogen oxides. When putting environmental concerns into the mix, petrol engines have a small advantage compared to diesel.
Bottom line? If you are looking for a lightweight car that goes from zero to 60 in the eye, a petrol engine can be the best choice. If you are looking for a car to take a boat to the lake this weekend, diesel can be the way.