Which engine is better: diesel or gasoline?

 

When buying a car, most people ask themselves the question: which one to buy? Diesel or gasoline engine? It is impossible to answer this question at once. Consider the factors that will help you make the right decision. But the question of what to do with a car that has long fallen into disrepair, the answer is to contact a company that specializes in scrap cars mississauga.

 

A car equipped with a diesel engine, in the process of operation will significantly save your money, due to lower fuel consumption. This is explained by the fact that the diesel engine of a passenger car has a compression ratio of 20-22 units, and gasoline engines have 9-10 units, which provides a higher efficiency. In addition the diesel engines has a qualitative regulation of the working mixture, i.e. almost the same amount of air is delivered into the cylinders, and the amount of fuel used increases with the load, regardless of the crankshaft speed and load. Another fact: at full power the weight of fuel injected is 1.5-1.7 times less than that of a gasoline engine.

 

Also, diesel engines have an actual compression ratio. I.e. pressure and temperature of the end of compression, does not depend on the load, and the working mixture is always very lean. Here are a few factors that provide diesel engines with high efficiency of combustion and subsequent expansion and at partial load modes.

 

It should be noted that the stability of the adjustment parameters of the fuel supply system in diesel engines is higher than in gasoline engines. In the process of operation, it is necessary to strictly control the quality of air and fuel purification. It is also necessary to exclude the possibility of engine overheating, which immediately affects the work of injectors and piston group.

 

As for durability: Diesel engines are more durable than gasoline engines. This is explained by the fact that a stronger and tougher design of the cylinder block, crankshaft, details of the cylinder-piston group, cylinder head and the use of diesel fuel, which in contrast to gasoline to a known extent is also a lubricant.

 

The disadvantages of diesels are as follows: heavy weight, lower liter capacity, increased noise due to high combustion pressure and difficult to start the vehicle at sub-zero ambient temperatures. In the course of operation, plunger pairs of the high pressure fuel pump are worn out, the tightness of the injector needle is broken, which leads to poor spraying at low start-up speeds (70-90 rpm). At the same time, as a result of the resulting wear of the cylinder and piston group at such RPM the compressed air breakthrough into the crankcase noticeably increases, and hence the pressure and temperature do not reach the values necessary for the ignition of the atomized fuel.

 

The disadvantages of diesel engines are their heavy weight, lower liter capacity, increased noise due to high combustion pressure and difficult starting at sub-zero temperatures, especially in cars which have gone 100 000 km or more.

 

In the course of operation, plunger pairs of the high-pressure fuel pump wear out, sealing of the injector needle is disturbed, which leads to poor spraying at low start-up speeds (70-90 rpm). At the same time, as a result of the resulting wear of the cylinder-piston group at such speeds noticeably increases penetration of compressed air into the crankcase, and thus the pressure and temperature do not reach the values necessary to ignite the atomized fuel.

 

Nevertheless there are simple enough devices, which will dramatically improve the starting of diesels at low temperatures, including the heat exchange device, installed for the period of winter operation in the intake manifold. The experience of diesel engines operation allows us to conclude that the above mentioned changes, which take place in the fuel equipment and cylinder-piston group, almost do not cause power reduction and increase in fuel consumption. Engines are repaired mainly due to an increase in lubricating oil consumption, which can be easily determined by refilling and the appearance of blue smoke, which is formed due to oil combustion.

 

Gasoline engines have higher rpm, higher liter power, lower noise and vibration. The regulation of the combustible mixture in them is mainly quantitative. Therefore, at low and medium power (passenger car engines operate mainly in these modes), the actual compression ratio is low, i.e. as a result of throttling at the intake and partial filling of the cylinder instead of the compression pressure, for example 2.5 MPa at full power, the mixture is compressed to 1.0 MPa. Hence the low efficiency of combustion and subsequent expansion, and hence the high fuel consumption.

 

Thus, if at nominal power the effective efficiency of the gasoline engine is 20% lower than that of the diesel engine, then at partial modes the gap increases to 40% or more. This is confirmed by numerous comparative operational tests of cars with diesel and gasoline engines of the same capacity. Reduction of fuel consumption per 100 km of route, depending on driving conditions (in the city or on highways) is 25-50%.

 

As for the toxicity of exhaust gases, the improvements of gasoline engines over the last decade, including piston processor-controlled direct injection injectors, have significantly improved this indicator. However, many experts from leading automobile companies, such as Volkswagen, believe that diesels remain the most promising engines when it comes to higher environmental and fuel consumption requirements.

 

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