As the power source of the automobile, the performance of the automobile engine directly determines the overall performance of the automobile. As well as the performance of automobile engine and the effect of automobile power modification. It not only depends on the design of the engine itself, but also is closely related to other components around it, such as intake and exhaust system, oil supply system, ignition system and electronic control system. The intake and exhaust system is like two door gods in charge of the lifeline of the engine. If something goes wrong with them, the engine will not work normally, which will affect the performance. But for many car owners, they are more concerned about the integrity of the car appearance, and rarely do in-depth research on the exhaust system of the car. If you want to study it, I'm afraid it's the tail of the exhaust. After all, it is difficult to see the internal structure of automobile exhaust from the appearance, and many people will think that the exhaust pipe is working normally as long as it is not blocked. The exhaust system of automobile is generally composed of exhaust manifold (exhaust banana), three-way catalyst, muffler (tailpipe) and exhaust pipe. The design of these parts is very particular, especially the exhaust tail drum. Because the exhaust tail drum not only plays the role of noise elimination, its structural form directly affects the function of the exhaust system. To understand the exhaust tail drum, click "Deconstruct the essence of exhaust tail drum". Photo: Honda CR-Z(ZF 1) adopts exhaust tail section. The larger cylindrical structure in the figure is the exhaust tail drum. There are many common exhaust tail drums, but they are all larger than the pipes of the exhaust system and easy to identify. This time, in order to let everyone know more about the exhaust tail drum and uncover the mystery of the exhaust system, we dismantled the original exhaust tail drum and the modified exhaust tail drum of a Suzuki Big Dipper. Photo: Suzuki Big Dipper original tailpipe exhaust route map. As shown in the above figure, the exhaust tail drum of Suzuki Big Dipper is a typical back pressure design. Exhaust gas first enters the tail drum from the pipeline ① and quickly fills the exhaust gas chamber ② behind the tail drum. Because this waste gas chamber is closed, the waste gas can only return in the same way, flow into the middle waste gas chamber ④ through the small holes in the pipeline ③, then flow to the exhaust pipe ⑤ through the grille, and finally be discharged from the exhaust pipe ⑤. The original tail drum, the appearance is so simple. If you don't open it to see what it is, I believe everyone will not think that the flow of waste gas is so complicated! Although this complex wiring design can play a good role in back pressure and help to improve the torque of the engine in the low speed range, if the engine climbs to the high speed range, it will be a little overwhelmed and the horsepower output in the high speed range will be reduced. So, what about modifying the exhaust tail drum? Figure: According to the design of the modified exhaust tail drum, a three-dimensional model is established. The size is not accurate, but it can clearly express the structure and principle of the modified exhaust tail drum. From the design of refitting the exhaust tail drum, the engine exhaust gas enters the tail drum from the red pipeline and then is discharged from the blue pipeline, and the whole tail drum is filled with sound-absorbing cotton. It should be noted that this design of exhaust pipe winding tail drum cancels the sealed air chamber of the original exhaust tail drum, and the back pressure effect is realized by plugging sound-absorbing cotton and extending the exhaust pipe line. Compared with the original tail drum, the exhaust resistance is greatly reduced, which is beneficial to the dynamic performance of the engine in the high speed range, but the reduction of back pressure effect means that the low-speed torque of the engine is weakened. Figure: Anatomical diagram of modified exhaust tail drum. Photo: Big Dipper installed and modified exhaust tail drum real shot. Summary: By comparing the original exhaust with the modified exhaust tail drum, we can easily draw the conclusion that for general economy cars, the original exhaust design will fully consider the exhaust sound and low torque of the engine, and will deliberately increase the exhaust resistance. Although this design is helpful to improve the low torque of the engine, it will greatly weaken the high torque of the engine. The modified exhaust can be matched with different tail drums to meet the needs of different driving habits. If low torque output is needed, a set of exhaust with high back pressure (exhaust resistance) can be modified, and if high speed output is needed, a set of exhaust with low resistance can be modified.