The modification of exhaust system can be the introduction of automobile modification. Cars mainly modify their own cars, and many of them first think of exhaust systems. However, many car owners will pay attention to the knowledge. Perhaps most of the modified exhaust systems at this stage are for appearance, and the "long-time" exhaust sound running in the street is really hot! This time, it is better to talk about tail gas modification, so that all car owners who want to modify it have a more rational understanding of this. 1. The part connected with the exhaust port of the engine cylinder head is called exhaust manifold, commonly known as dead banana, which is used to collect the exhaust gas flowing through the exhaust port of the cylinder head and make it discharged smoothly; 2. Among the turbocharged engines, the one behind the outlet of the turbocharged exhaust port is called the front pipe, and Chinese is the first batch; In addition to acting as a bridge to make exhaust gas flow into three-way catalysis, there is also a soft connection between the engine and the exhaust pipe in NA engine. 3. Then there is the "three-way catalytic converter" which plays an environmental protection role. I don't need to know the function, just to prevent my car from being stopped all day to measure the exhaust gas fine; 4. Then the front silencer. If it is used in racing cars, it should be said that drums have little effect and can even be cancelled. But if it is a streetcar modification, it is simply to reduce the phenomenon of * * * when exhausting; 5. The rear fender is called the rear muffler, commonly known as the dead throat, and it is also considered to be the most modified part at present. The modification of the exhaust system, to put it bluntly, is to reduce the exhaust back pressure. The definition of back pressure is that the pressure in the exhaust pipe hinders the force of the exhaust pulse. Reducing the back pressure is actually to make the alternation of suction and exhaust smoother, which is equivalent to prolonging the overlapping time of valves. Retrofitting the exhaust system should start from the middle and tail. This concept is known to domestic refitters, but many stores will take it for granted, or say it out loud regardless of the willy-nilly. In fact, the key to refitting the middle (drum) to the tail (drum) is to take care of the shape design, which can be divided into "short and thick" design, that is, to reduce the pipe length and increase the pipe diameter as much as possible. This modification method is not suitable for daily driving, because the back pressure is low, and the exhaust gas flow rate is slow at middle and low speeds, resulting in the mixture in the cylinder being discharged without complete combustion. The torque performance is naturally poor at middle and low speeds, but the pulses are dense at high speeds. The other is the "slender" mid-tail exhaust pipe given to Bora by Neuspeed, the first turbocharged model. The modification only changed the material of the pipe, did not change the original bending shape, and even the tail was slightly thinner. The advantages of this modification are that it is suitable for daily city driving, the pressure in the pipe is high, the exhaust gas can be discharged quickly, and the torque at medium and low speeds is increased, but the high-speed horsepower is not flattering. As for the tail drum, there are only two forms, one is called reflection, and most of the original tail drums are this form, but the problem is that the resistance is large and the power loss is serious; The second type is called linear type, and the principle is simple. The import and export are basically in a straight line, and the noise reduction method relies solely on sound-absorbing cotton and cutting. Almost all modified tail drums are straight. Therefore, it is wise to adapt to your daily needs and driving habits before changing to the middle to the end. From the middle to the end, it should be a three-way catalyst, which can slow down the flow rate of exhaust gas and form resistance. However, there are many problems in reforming catalytic converters in China, such as the use of pseudo-catalysis, good performance and low price. However, if the detected exhaust gas is caught and needs to be detected, the exhaust gas is definitely unqualified! However, if it is replaced by a truly modified catalyst, the price will be very expensive. Although the performance will be greatly improved compared with the original factory, it is true that not everyone can afford or be willing. Ten thousand yuan to twenty thousand yuan is a very common price. Dead bananas are the most important part of the exhaust system transformation, and the effect is also the most obvious. The original dead bananas are generally cast iron, and some car manufacturers will choose stainless steel, like BMW. Due to the mass production of original exhaust bananas, not only the inner wall is rough, but also the length of exhaust manifold may be inconsistent, so the so-called exhaust interference phenomenon appears. So, why are there few modified dead bananas on the market? I think a big reason is that BMW's original products are already stainless steel, with high quality and high performance. Dead bananas used for modification are generally made of stainless steel, which takes advantage of several advantages: good high temperature resistance; The wall is thin, so the overall weight is light; Although the inner wall of stainless steel pipe does not need polishing and sliding, it is much smoother than the original pig iron products, which is beneficial to the movement of waste gas. In addition, it is easy to bend and cut, and it is easy to achieve the goal of equal length, especially when NA is changed to TURBO. In order to facilitate the accommodation position, stainless steel dead bananas will inevitably be used. In fact, the equal-length manifold has a positive impact on the improvement of horsepower. Theoretically, the working sequence and time of each cylinder are the same. If the length of the exhaust pipe is different, the exhaust efficiency of each cylinder will be deviated, which will reduce the efficiency, and there will also be pressure difference between manifolds. The final result must be chaotic exhaust pulse, and the horsepower and torque output are naturally low. On the turbine engine, academically speaking, it is to make the turbine blades on the exhaust side suffer quantitative, smooth and continuous blows as much as possible, so as to greatly improve the upper limit of turbine speed, efficiency and stability, and thus improve the supercharging pressure. The first batch, the front pipe, is the exhaust pipe connecting the dead banana and the three-way catalytic fruit (the turbine engine is the exhaust outlet to the three-way catalytic fruit). The part of NA car that few people will change is because the effect is not obvious. However, if the exhaust of the turbine engine is modified, it will basically be replaced in the first batch. Why? This is because it is related to another proper term: secondary pressure relief. Very simply, the turbine blades are driven by exhaust gas, and the smoothness of exhaust gas in this section directly affects the working speed and limit of the turbine. The principle is a bit like a dead banana on the na car. The reformed dead banana can basically overcome the shortcomings of the original banana. Although modified dead bananas have many advantages, they are expensive. For example, a modified dead banana used in AUDITT 1.8T costs as much as 16000 RMB, which is really beyond the affordability of ordinary people, so some cheap products have appeared on the market. Cheap products can't be said to have no effect at all, but they will certainly have some effect, but whether they can maximize their effectiveness is another matter. Why some brands of goods can be sold so expensive is largely due to the high cost of testing, except for import channels. Testing is not as simple as simply measuring the position. If so, buy some stainless steel pipes and bend them to sell! What engineers are needed there and what engine test stands are needed? Most exhaust systems on the market refer to the tail drum, because there are many people who modify it, and the price is not too expensive. There are also deals that are several hundred yuan cheaper. But those products are not supported by test data, and no one can tell where the actual use effect is. I believe that there are no shops that advertise how many horses can be improved so that he can really get the data. There are basically several kinds of exhaust refits in the market: the exhaust system is the whole exhaust flow from the exhaust port connected to the combustion chamber, through the exhaust manifold (that is, the head section), the middle section of the exhaust pipe (including the catalyst section) to the tail section of the exhaust pipe. The exhaust system of automobile engine has two main functions: one is to guide the high-temperature exhaust gas after combustion to the back or side of the car to avoid affecting the occupants in the car; The second is to reduce the noise generated in the process of high temperature and high pressure exhaust gas discharge to the allowable limit by using "muffler". The exhaust manifold is first encountered in the whole exhaust process. The most important thing in the design of exhaust manifold is to avoid the exhaust interference between cylinders, so that the exhaust gas can be completely discharged from the pipeline as much as possible. The middle section of the exhaust pipe itself plays a simple role. As long as the exhaust gas from the exhaust manifold is introduced into the exhaust tailpipe, some exhaust systems will install an expansion chamber in the middle section to reduce the exhaust gas pressure. Because the high-temperature and high-pressure exhaust gas inside the engine is still at a high pressure when it enters the exhaust manifold, it will produce shock waves when it hits the exhaust manifold wall, and its frequency can reach thousands of times per minute, and it will emit annoying noise with quite high frequency every time, so it needs to be treated well. When the exhaust gas passes through the exhaust manifold, its shock wave has dropped from supersonic to transonic or even lower, but the noise generated by the shock wave is still very loud. It is not enough to reduce the power of the pipeline only after the middle section. It is necessary to install "expansion chamber" and "muffler" in the middle section and the tail section to offset its power. Some exhaust pipes are designed with only one muffler at the tail, while others will add an expansion chamber in the middle. The muffler and expansion chamber are similar in appearance, but the difference is that there are multiple baffles or perforated straight pipes inside the muffler to absorb sound waves and reduce the flow, while the expansion chamber is just a large hollow container with simple use. There will inevitably be back pressure in the exhaust system itself, which is limited by the intake manifold, internal pipeline and muffler. Designers should not only consider reducing noise, but also try not to hinder the emission of exhaust gas, as well as the output curve of the engine, catalytic converter and many other factors. How to find a balance between them will be a big problem. During the exhaust process, there is a short pipe in the middle of the engine block, which is generally called an exhaust hole, from the exhaust valve of the combustion chamber to the exhaust manifold. The most controversial issue is back pressure. Some people think that too low back pressure will cause the combustion flame to rush out of the exhaust valve directly and burn out the exhaust valve, so there must be moderate back pressure to resist the flame when the exhaust valve is opened, and too low back pressure will also cause the adverse effect of power output decline. Another faction supports that the lower the back pressure, the better, and the smoother the exhaust, the better the effect. Can the silencing gas with large diameter and small resistance make the exhaust smooth? Actually, it is not. Because we see that many people have replaced the whole exhaust pipe at the head, middle and tail without detailed calculation, but it has caused the embarrassment of weak acceleration. This truth lies in the word "shun". Some people may ask, it is so "smooth", why not "smooth"? Careful observation shows that when the diameter of the exhaust pipe is too thick, each exhaust pulse cannot fill the whole pipe diameter, and then the exhaust gas will form turbulence in the pipe diameter, but the exhaust is not smooth. Similarly, why are there different ways to modify exhaust pipes, focusing on low-speed torque or high-speed output? With the same theory, it can be explained that when the pipe diameter is large to a certain extent, enough air displacement is needed to fill the whole pipe diameter, so this is a method that usually focuses on high-speed torque, and low-speed torque cannot be taken into account. The exhaust head has the greatest influence on the total exhaust efficiency. In order to achieve a smooth exhaust state, the distance from the exhaust valve of each cylinder to the joint of the exhaust pipe of each cylinder must be equal, because the ignition of each cylinder has a certain order. If the distance between each cylinder and the joint is not equal, and the distance traveled by each cylinder is not equal, then the exhaust will be blocked at the joint together due to the time difference, which will affect the exhaust efficiency. However, the original factory may not necessarily lengthen the exhaust distance of each cylinder to the same length for cost reasons. Therefore, when you have a catalytic converter, muffler and exhaust head sections with different lengths on your exhaust system, it is undoubtedly worse and the power output is greatly affected. If you just want to have a nice exhaust sound, you just need to replace the muffler at the tail. The added benefit is that you can get "some" performance improvement by the way, but the amount of this "some" depends on the original design. If the middle muffler designed by the original factory has little resistance, your car may feel reborn as long as the rear muffler is replaced. 1. Front section: Also called exhaust manifold, it connects the exhaust gas from each cylinder to the middle section. 2. Middle section: A catalytic converter is installed, which is mainly used to reduce the emission of nitrogen oxides, HC and other gases in waste gas and prevent air pollution. 3. Tail: It has the function of silencing and reducing exhaust noise. That is, there is a lot of weight behind the last exhaust pipe. Of course, if the exhaust pipe is broken in three sections, you will hear a lot of exhaust noise. At this time, you should find out which section is missing and replace it. Exhaust pipe classification: (1) Generally, the original factory pipe (2) back pressure pipe (as environmentally friendly as the original factory) has the same principle as the original factory, but the sound will be better than the original factory. Most of the original factories use this kind of pipeline, which mainly produces a pressure that will return to the cylinder through the volume change of the grille muffler or pipeline in the pipeline. When the engine is ignited, the piston begins to make a radial power stroke, and the exhaust valve will open before the piston reaches the bottom dead center. At this time, the back pressure in the pipe will prevent the exhaust gas from rushing out and make the mixture burn completely. However, if the back pressure is too strong, the exhaust gas can not be completely discharged from the cylinder, which will cause the exhaust gas and mixture to ignite and reduce the combustion efficiency. Of course, the most direct is the advantage of horsepower output L: low noise and good low-speed torque. Disadvantages: exhaust gas can not be discharged quickly at high speed, and the engine power output is low (one star). (3) Semi-back pressure pipe, of course, the back pressure is lower, and the exhaust compliance is better than that of back pressure pipe. It is located between the back pressure pipe and the straight pipe to obtain the starting torque. Exhaust compliance is better than back pressure pipe. Of course, the medium and high speed torque is also better than the back pressure tube. Disadvantages: Good starting and tail speed torque. The noise is too loud (two stars) and the volume is too loud. (4) The acceleration of the straight-through pipe will be better than that of the back-pressure pipe, but the biggest disadvantage is that it is noisy and will make the "police cup" chase you. The back pressure is extremely low. Advantages of high torque at medium and high speed: smooth exhaust, and high torque at high speed. Disadvantages: low speed, soft force and loud noise (some people say that it is easy to burn out the valve, I don't know if it is true). Volume: super large (four stars) (5) Semi-straight pipe is actually the same as semi-back pressure pipe, except that the diameter of exhaust port is larger than that of semi-back pressure pipe: the starting torque is lower than that of semi-back pressure pipe. However, the products and products that can be used at medium, high speed and high torque are as follows: the first one is made in China; The second is a Japanese modified brand; Among them, the original modified car factory products are: Mugen, NISMO, TRDMugen: Japan Mugen has always been known for its outstanding achievements in the field of racing. Since the Japanese law HondaCivic was promulgated for eight generations, MUGEN has been studying how to make Civil return to the game. Until March 2007, the goal of making racing cars into OneMakeRace was established based on CivicTypeR (code name FD2), and MugenRC was born under this concept! Different from Mugen road models (such as MugenRR, MugenCivicTypeR, etc. ), MugenRC's main demand from the beginning of development was to participate in the CivicOneMakeRace unified specification competition, so there were no redundant comfort equipment in the car, including air conditioning, stereo, decorative board, etc. All of them are hollowed out to facilitate lightweight, and also increase the rigidity of anti-roll W. Because the appearance part is basically extended by CivicTypeR aerodynamic package. 踋 3? Crispy? In order to maintain the fairness of the game, the red-headed engine S [K20A] is used as the main engine. So strictly speaking, MugenRC is not a commercial version of CompleteCar, but a real OneMakeRace car, which is sold to major racing teams. It is "hand-made" by Mugen's M-TEC factory in saitama, and is divided into three models: basic version, standard version and full version. The price is 6,247,500 ~ 7,822 yen, 500 yuan RMB. Moreover, MugenRC is only sold in the Japanese market. At present, only Japan has held Civic Uniform Specification Competition (full name Honda Exciting Cup Civic Makerase 2008), so it is naturally unnecessary to export tailored MugenRC. NISMO: It is an all-stainless steel exhaust pipe specially designed for RB26DETT engine of Skyline GT-R. This exhaust pipe is characterized by double pipes from the first section through the catalyst to the central muffler, and then assembled into a large-diameter single pipe and led to the straight-through tail muffler. Due to the double-tube design from the beginning to the interruption, the exhaust pressure can be reduced, and the low-speed acceleration is taken into account, and the exhaust efficiency is excellent at high speed. TRD: Tailored dovetail exhaust components are designed for Reiz, and the silent invisible internal back pressure drum is adopted in the design, focusing on the performance of the front. The biggest feature of TRD product is that it exhausts in the form of dark throat, which can easily improve the dynamic performance of the vehicle without replacing the handle of the tail pump. The other category is the products of manufacturers of comprehensive refitted parts: Apex, Blietz, Fujii, ARC, INPUR, HKS, RSR, Jasma, Top, FGR. . . APEXi: It occupies a certain position in the field of automobile modified electronic products. However, APEXi, as a manufacturer of automobile modified products, has covered most of the performance products of automobile modified, and the exhaust system is one of them. It is believed that users will first consider the popularity of products before buying high-performance modified parts, and often brands with higher popularity will become users' first choice. Speaking of popularity, the name APEXi will not be unfamiliar to users and will give buyers confidence. The exhaust pipes printed with APEXiLOGO are mostly made of stainless steel, which can improve the horsepower output of the engine and pay attention to its durability. In addition, the exhaust pipe of this brand corresponds to a wide range of models. According to the pipeline direction of different models, a variety of exhaust bananas and back pressure/straight tail drums with different diameters in the front, middle and rear sections are made. However, due to the numerous branches of the products, it is impossible to list the data in detail. Blitz: "Nur" series is the abbreviation of the German New Bogeling circuit.