Explanation of turbocharging principle

You said that air and fuel were fully burned in a certain proportion, the air intake increased, and the fuel injection increased. This is correct, but it is correct for natural inhalation. The condition of turbocharging is that there is a suitable fuel injection system, such as in-cylinder direct injection. TSI is not uncommon, is it? TFSI has seen it. These are all imitations of diesel engine injection methods, as well as multi-point injection. As long as the fuel injection system meets the requirements, it can be installed. Therefore, ordinary gasoline engines can't be installed casually, but diesel engines have almost become standard.

Because the diesel engine relies on the way of deterioration adjustment to adjust the torque, there is no throttle, and the amount of air inhaled in each cycle is not much different. The difference in mass flow is mainly caused by the change of speed, so the mass flow span of the diesel engine is only about 6.5: 1. In contrast, traditional gasoline engines (gasoline engines other than GDI) rely on variable adjustment to adjust torque and air flow through throttle. With the change of load, the air intake in each cycle changes greatly, and the speed range of gasoline engine is much larger than that of diesel engine, so the mass flow span of gasoline engine can reach 75: 1, which is close to 12 times of that of diesel engine. This leads to poor transient conditions of turbocharged gasoline engines. Mechanical pressurization does not have this problem.

In-cylinder direct injection gasoline engine has full throttle under low working conditions, similar to diesel engine; Only under high working conditions will the throttle opening change with the change of load. Therefore, GDI's mass flow span is close to that of diesel engine, and it is also suitable for turbocharging.

Therefore, the air-fuel ratio of diesel engines is almost too thin except for full horsepower. As you said, it should be all white smoke, but white smoke will only appear when the oil is burning. Diesel engines are powered by fuel injection, and there is really too much air. The diesel engine is always in the best combustion efficiency, so there should be enough air to participate in the reaction. In addition, the supercharger should have more engine displacement to determine the size, such as the idle supercharger of the truck. In fact, the principle of gasoline pressurization is similar, that is, the fuel is too thin to achieve the best combustion efficiency, but the gasoline is too volatile, so it is necessary to install more fuel injection methods.