Nowadays, there are more and more turbocharged cars, but many people don't know much about turbocharged except that it can improve power. Today, let's share some facts related to turbocharging that make you feel incredible.

1. The supercharger also turns at high speed at idle speed

Amy bought a car, a turbocharged engine, which can output maximum torque at 1500 rpm. Amy thinks that the supercharger will start to work when the engine speed reaches 1500 rpm, and will not work when the engine speed is lower than 1500 rpm.

Amy's idea is obviously wrong. Because as long as the engine starts, the supercharger will turn with it. The speed is related to the size of the supercharger. If the supercharger size is large, the speed is low, and if the supercharger size is small, the speed is high. For example, in order to reduce the maximum torque speed of ordinary household cars, the supercharger is generally very small, so the speed of the supercharger can be as high as two or three thousand revolutions at idle speed.

Because the supercharger is driven and rotated by the engine exhaust gas, the supercharger will rotate as long as the engine produces exhaust gas. This is like putting a small windmill at the exhaust pipe of the car, and the windmill will be blown to rotate after the engine is started. It is just that the current speed is relatively low, and the supercharging effect is not enough.

2. The supercharger is rotated by "explosion"

We all know that when the engine works, the mixture burns and expands, pushing the piston downward and outputting power. After the piston reaches the bottom dead center, it starts to move upward and enters the exhaust stroke. Many people think that the exhaust stroke is pushed out by the piston.

If this is the case, the turbocharging technology will never be realized, because the linear speed limit of the piston is 27 meters/second, and the supercharger cannot be pushed at all.

The fact is that the time of each stroke of the engine is very short. Although the mixture has completed combustion during the exhaust stroke, the residual exhaust gas pressure is still very high. When the exhaust valve is opened, the high-pressure exhaust gas will "sprint" to the exhaust manifold at the speed of sound, producing a violent shock wave impacting the turbine blades. Because of the enough energy and the small rotation resistance of the supercharger, the supercharger will rotate at a high speed.

3. Whether the supercharger works depends on the power demand, not the speed

There is a wastegate beside the turbine of the supercharger. When the supercharger is not needed, the bypass valve will open. A part of the waste gas will bypass the turbine and flow away directly from the bypass valve, which can reduce the exhaust resistance. When it is necessary to boost, the bypass valve is closed, and the exhaust gas is concentrated to drive the turbine, so the supercharger can provide sufficient boost pressure.

When the bypass valve is opened and closed depends on your power demand. In short, when the power demand can be met without pressurization, the bypass valve will be opened. On the contrary, the bypass valve will be closed and enter the pressurization state to provide sufficient power. For example, if you step on the accelerator when idling, and the engine speed is up to 3000 rpm, the engine can reach this speed even without supercharging, then the bypass valve will open and the supercharger will not supercharge.