Diesel engines are better than petrol engines due to its efficiency ,power & cost. And petrol engines are better than diesel engines due to its speed, weight , lower compression ratio & pollutions. For small & lighter weight vehicles petrol engines are better than diesel engines. For heavy vehicles diesel engines are better than petrol engines.
I think that diesel engine is better than petrol engine because there are many reasons on the basis of which I can say that the diesel engine is better 1. The price of diesel is lower as compared to petrol. 2 .the efficiency of diesel engine is greater than petrol engine due to higher compression ratio it can pull heavy loads. 3 .diesel engines are heavier in weight so these engines can remain safe for longer time.
Well a petrol engine is better than diesel engine because...spilled out petrolium products from petrol engine are less harmful to the environment than a diesel engine. SPM emitted by petrol engines are larger in size compared to diesel engine. So a petrol engine is better than a diesel engine.
The most distinguishing feature of the diesel engine is that it uses compression ignition to burn the fuel, which is injected into the combustion chamber during the final stage of compression. In a diesel engine, fuel is injected at high pressure into the hot, compressed air in the cylinder, which causes it to burn and no spark is required for this. Thus, “compression ignition" is done rather than "spark ignition". The petrol engine is known as a “spark ignition” engine.
The Petrol engine uses the Otto cycle in which a fuel/air mixture is ignited by a spark plug. The air and fuel mixture when ignited by a spark burns and thereby expands to force the piston down. In case of a petrol engine, fuel and air are pre-mixed usually before compression. Earlier the pre-mixing used to be done in a carburetor but now (except in the smallest engines) electronically-controlled fuel injection is used for this. The pre-mixing of fuel and air makes a petrol engine to run at a much higher speed than a diesel. However, it severely limits their compression, and thus efficiency.
Diesel engines offer better fuel efficiency when compared to petrol due to the fact that they have higher compression ratio. Another advantage is that, a diesel engine can be more easily turbocharged than a petrol engine because of the fact that if the compression ratio and the pressure in the cylinder are high during the inlet stroke, the mixture starts to burn to soon, while the piston is on its way up. The diesel engine has no fuel in the cylinder and thus allows the turbocharger to suck as much air as it can without creating any problem.
The higher compression ratio is helpful in raising fuel efficiency. Diesel engines are much more efficient than petrol engines when at low power and at engine idle. Diesel engines, unlike the petrol engine, lack a butterfly valve (throttle) in the inlet system, which closes at idle. This creates parasitic loss and destruction of availability of the incoming air, reducing the efficiency of petrol/gasoline engines at idle. This mechanism makes the diesel engine an attractive choice for many. Diesel engines are left idle for many hours or sometimes days in many applications, such as marine, agriculture, and railways. The engines are more efficient when compared to petrol engines of the same power. They consume significantly lower fuel and offer better mileage.
A diesel engine can relatively last longer, due to the fact that petrol destroys lubrication and diesel doesn’t. While all the above support diesel engines, a major advantage of petrol engines is that they are relatively lighter than diesel engines. Engine weight is an important factor which affects speed and performance of a car. This is one of the reasons why some of the fastest cars in the world run on petrol. It should be noted that even though diesel engines are heavier and make the automobile heavy, they have more torque.
