Audi A6L About Turbine

This rider need not worry. This sound is made when the pressure reducing valve of turbocharged engine releases pressure. It can be said that all turbocharged engines will produce this sound, but for daily civil vehicles, manufacturers will treat this sound as noise when designing and reduce it as much as possible. The method is to vent the pressure into the intake manifold, so the noise is very small-this pressure relief method is called internal venting.

For ordinary civilian vehicles equipped with turbocharged engines, the "hissing" sound of pressure release is generally imperceptible without careful listening. This is just like for ordinary civilian vehicles, engine noise and rumbling exhaust sound are negative parameters (and high-performance vehicles can sometimes emphasize this sound), and the original factory design will try to eliminate this sound as much as possible. For riders who like driving pleasure, this sound has become a catalyst to stimulate their driving passion (we often see that the exhaust pipes of many cars are replaced by gun barrels, and the sound is rumbling and loud).

In addition to stimulating driving passion, "Hyun" is also one of the demands of modification. Many people want to replace their cars with super-high performance cars, even if the power of the cars is not particularly strong. Generally speaking, the size of the "hiss" emitted by turbocharged engines is related to the supercharging intensity-large turbochargers are more likely to emit such a sound. Therefore, if the sound is loud, it can appear that the supercharger of this car is relatively large, which makes people feel dazzling.

Therefore, many refitting enthusiasts change the internal pressure relief of their civil automobile engines (such as Bora 1.8T, Passat 1.8T) to external pressure relief, and further increase the "hissing" sound, which is similar to the tubular exhaust pipe. So, why does the turbocharged engine make such a sound?

When we step on the accelerator pedal to accelerate, the throttle opens and the engine will make a "hmm …" sound with the increase of vehicle speed. The exhaust energy discharged by the engine at high temperature and high pressure will drive the exhaust turbine to rotate. When the speed of the turbocharger reaches the working speed (that is, the turbine speed exceeds 654.38+ million revolutions per minute), the turbocharger will compress the surrounding air, thus increasing the air intake of the engine and improving the power of the engine.

When we collect oil, the throttle opening decreases rapidly until it is in the closed idle state, which means that the engine does not need air intake, otherwise the air flow in the intake pipe will be blocked at the throttle. But at this moment, the turbocharger has not stopped working! Due to inertia, the turbocharger still keeps rotating at a speed of over 654.38+ million revolutions per minute. Now it is conceivable that the air is still being compressed into the intake pipe. If this part of high-pressure air cannot be discharged in time, the pressure in the intake pipe will rise rapidly, which may cause the throttle valve to be damaged or the intake pipe to burst.

At this time, it is necessary to install a pressure relief device in the intake pipeline to discharge the excess high-pressure air compressed by the intake turbine in the pipeline. In fact, the pressure reducing valve is a valve installed on the intake pipe to control the boosting pressure. The opening and closing of the pressure reducing valve is controlled by an electromagnetic coil operated by ECU (Electronic Control Unit). ECU will make a judgment according to the pressure of turbine outlet pressurization. Once the pressure exceeds the critical value, the electromagnetic coil will be turned on or off, and the pressure relief valve will be turned on or off.

When the pressure reducing valve is closed, it is based on ensuring that there is enough intake pressure in the intake pipe. When the valve is opened, it can release excess gas into the atmosphere, reduce the pressure in the intake pipe and protect the engine intake pipe. Therefore, the "hiss, hiss" sound we heard on the modified car is the sound when the pressure reducing valve releases pressure and exhausts.

In fact, the "hissing" sound from the modified car has no significance to the improvement of engine performance, and can only render the illusion of a large boost value. Relatively speaking, the greater the boost value of the engine, the more air discharged by the pressure relief valve, and the greater the theoretical noise. When refitting a car, the sound of the pressure reducing valve is amplified, just like using a gun barrel to exhaust the pipe-the action is cool, but it has no practical effect.