GDI engine: device and features

GDI-engine refers to units with direct fuel injection, in which the combustible mixture penetrates not into the intake manifold, but directly into the cylinders of the engine. At the moment, such power plants are equipped with Japanese cars. In particular, they are Toyota, Nissan and Mitsubishi.

GDI-motors and their devices

So, let's analyze the design features of this unit. As we have already noted, the GDI-engine has a system of direct fuel injection into the cylinders, which allowed to significantly reduce the average fuel consumption to 20-30 percent. Also, this unit is characterized by the fact that at low and medium loads it is layered mixture formation. In this case, the fuel enters the cylinder of the GDI engine with a pressure of the order of 100 atmospheres, as a result of which it does not have time to be saturated with oxygen. For comparison, in conventional injection engines, fuel flaring occurs at a pressure of 3 atm. Because of this, part of the gasoline remains at the spark plug, and exactly at the time of sparking.

When this amount of fuel enters the intake manifold, it evenly fills its entire volume, thereby rapidly evaporating and forming a poor mixture. In this case, gasoline without the penetration of oxygen will not burn, and most of it simply flies into the pipe. Usually in such cases, the engine overheats on the injector cars, and on the candles a white deposit is formed. What happens to the GDI engine? It does not form such a deposit, because its design lacks a throttle. It, in turn, grasps the air from the outside and delivers it to the cylinder (before it takes place the preparation of the fuel-air mixture). In this case, the motor does not spend its power on the intake of air, and this, as a rule, minus 3-5 horsepower. Also, the 18 GDI engine is distinguished by its high compression level, which is achieved due to the same missing throttle.

It should be noted that on the walls of the cylinder during the combustion of fuel formed a uniform layer of oxygen, which causes the mixture to quickly ignite and activate the piston. And how does the GDI engine work at maximum loads? If the principle of layer-by-layer mixing is applied in the first two cases, then this is not the case with full loads. Fuel in this case falls into the cylinder in a larger amount, and not as before, because of what increases its consumption and the level of concentration of harmful substances in the exhaust gases at the outlet. For this reason, all modern GDI engines are equipped with additional injectors on the intake manifold. They allow you to reduce fuel consumption to the level of conventional cars with injector installations. Thus, at maximum loads, it consumes an equal amount of fuel and produces the appropriate power, as well as conventional injector motors.

How to determine this effort?

Typically, the maximum load on the GDI-engine starts only at a speed of 120 kilometers per hour, so in most cases the unit economically absorbs fuel.