#New Year Hot Sale# Exhaust System and Modified Exhaust， GRWA2022 starts, and the series of products are on sale!（2）

From the rise of car modification to the trend, the exhaust system is a topic that cannot be bypassed. As a part of the core of the car's life, in the first half, we talked about the misunderstandings of exhaust modification and the principles of modification. Next, I will tell you about modification. The problems that are easily overlooked in the exhaust system and the differences in the materials of different products are convenient for you to pay attention to when purchasing products, and how to choose high-quality products and enjoy high-quality services.

Three、Problems that are easy to ignore when modifying the exhaust system

1、The importance of exhaust back pressure

Since the basic principle of modifying the exhaust is to make it smoother and make the exhaust resistance smaller. But in fact, the exhaust system is not the smoother the better. The working principle of the engine is that each cylinder burns in turn, and then exhausts, so the exhaust process is not continuously blowing exhaust gas out of the car, but the exhaust gas generated by the engine is wave after wave (at idle speed, due to the very low speed , we can feel it as soon as we put our hands on the exhaust) exiting the exhaust system.

Take general household models as an example, when the engine is working in the low-to-medium-speed area, each exhaust process will form a large pressure inside the exhaust pipe. When a wave of exhaust gas is discharged outward, a negative pressure will be generated behind the exhaust gas. For the next wave of exhaust, this negative pressure is equivalent to the suction force, which can help the next wave of exhaust gas to be discharged out of the car faster, and this cycle can improve the exhaust efficiency. This is the resonance effect created by what we call exhaust back pressure (also known as back pressure).

When the engine is at high speed, if the exhaust system is not changed, the excessive back pressure will cause excessive resistance in the exhaust pipe. When the engine is at a high speed, the working gap of each cylinder becomes smaller, so that the effect of the resonance effect becomes less pronounced than at a low speed. At the same time, the air intake and exhaust volume per unit time are greatly increased at high speed, and the original exhaust structure cannot cope with the increase in exhaust volume per unit time, resulting in the reduction of exhaust efficiency at high speed. If it is not smooth, the re-intake will also be affected, so reducing the exhaust back pressure can effectively improve the power performance at high speeds.

However, if the exhaust is too smooth and no resistance, it will weaken the suction effect produced by the exhaust back pressure, making the exhaust pressure very small and inefficient. This can explain why cars with modified exhausts tend to have less torque output than the original models at low revs. The setting of the back pressure depends on the demand for power characteristics. Car owners who emphasize low torque must not use an overly smooth exhaust system, while those who pay attention to the performance of high torque are suitable for retrofitting products with low back pressure.

In addition, for the modified exhaust system, it should also be selected for the specific model. Naturally aspirated engines with small displacement or low displacement and low-horsepower automatic transmission models have the characteristics of low torque and weak power output. Switching to a low-back pressure exhaust system will worsen the lack of low torque , not worth the loss. Therefore, the modified exhaust system should be selected in a targeted manner to obtain the desired effect.

In fact, this question involves the difference between general-purpose series products and customized products. Many brands do not have the R&D and production capabilities, and the car categories that can be satisfied are limited. If it is from a retail perspective, of course, it is possible, but if it is a service brand, it appears to be insufficient. GRWA obviously does not have this problem. General-purpose products can provide multi-brand products in addition to the established services. GRWA advocates the concept of "1000-machine service". As far as the special car ternary is concerned, it can provide matching products for more than 300 car brands, and also supply DPF to provide corresponding products for diesel vehicles.

In addition, excellent R&D and drawing capabilities can meet the needs of various users.

For example: Manifold products are famous for their diverse and complex processes. GRWA has complete production technology, including design, material selection, welding, ultrasonic cleaning, drying, positioning and proofreading, etc., and because of its mature technology, it can be produced effectively and stably. Supply, guarantee delivery, fully guarantee your interests, and grow together with customers are the characteristics of GRWA that are superior to other brands.

2、The most critical exhaust manifold modification and exhaust resonance effect

When it comes to modifying the exhaust, the first thing that comes to our mind is the modification of the exhaust tail section and the exhaust middle section of double-outlet, quad-outlet or large diameter. There are many products of different brands on the market for a certain model. In fact, except for the exhaust middle and tail section In addition to the modification, the most direct impact on the engine performance is the exhaust manifold. We all know that the engine needs to discharge the exhaust gas out of the combustion chamber after the working process, and each cylinder performs a cycle of suction and pressure explosion (four-stroke) in a fixed sequence. For the entire exhaust system, the most direct impact on the exhaust efficiency is The part is the exhaust manifold (called Basho in Guangdong and other places).

The exhaust manifold is directly connected to the engine exhaust passage and is also the first passage through which the exhaust gas passes after being discharged from the combustion chamber. The original exhaust manifold is usually made of cast iron with a large number of open molds. The inner wall is rough, which will form a certain resistance to the airflow, and because the position arrangement in the engine compartment must be considered, the original exhaust manifold does not consider each cylinder. The length of the exhaust pipe (except for some high-performance models), the different lengths of the manifold cause the exhaust gas of each cylinder to run different distances, so when they converge together, they will be blocked together, conflict with each other, and form a block. This phenomenon is more serious at high speed.

Most of the modified equal-length exhaust manifolds will be made of stainless steel with smooth inner walls, and the manufacturers who pay attention to the parts of the manifold connecting the base and the corners use a special welding process and try to ease the corners as much as possible. This achieves the effect of reducing resistance and accelerating airflow. The equal-length design is to solve the above-mentioned interference problem, so that the exhaust pressure value in each manifold is the same, so that the exhaust pulse is consistent (helps to exert the resonance effect of exhaust gas). ). In terms of structure, some exhaust manifolds will also add an additional set of pipes before the exhaust gas of each cylinder is aggregated together, such as the 4-out, 2-out and 1 exhaust manifolds that are often used in four-cylinder vehicles (one outlet pipe for each cylinder). , and then combine them into two, and finally combine the two pipes into one), the purpose of this approach is to appropriately increase the exhaust back pressure to retain the low-speed torque. Compared with the modification of the tail section of the exhaust, the well-designed equal-length exhaust manifold can effectively improve the power performance.

When purchasing a manifold, many customers will also choose a batch of bellows as the transition between the manifold and the elbow. In fact, the choice of the bellows also makes the modified exhaust smoother.

Some friends will ask if the car exhaust really needs this product, and the answer is yes! Failure to install bellows can seriously damage your exhaust system, such as damaging bolts, flanges, and even the exhaust manifold itself. It may take us less than half an hour to install a brand new bellows, so it only takes half an hour for us to drive safely and do what we need to do without worrying about being stopped by the traffic police and not being able to pass the annual inspection.

In addition to providing commonly used corrugated pipes, the newly emerging seam-welded corrugated pipes have continued to sell well in 2021. If you have not understood this product, it means that you are a little far from the market, and you need to hurry up to understand Demand, pay attention to GRWA, and will not miss any business opportunities!

3、Changing the position of the exhaust line reduces the passing capacity of the vehicle

Some exhaust systems that pursue high-horsepower output will be designed to have a pipeline layout that is as straight as possible, and no longer use the original exhaust reserved position of the chassis. This modification usually makes the exhaust pipe closer to the ground (larger diameter exhaust pipe). The air tail section also affects the passing performance), which makes the passing performance of the vehicle worse and increases the probability of underpinning. When refitting, it is necessary to consider whether the vehicle environment allows the reduced exhaust pipe height.

Four.The difference between the material of the exhaust system

The material of the exhaust system is also one of the key factors that we cannot ignore when refitting. Exhaust pipes of different materials not only affect the power performance, but also have a considerable difference in weight and sound. Usually the modified exhaust is made of stainless steel, and the smooth inner wall can improve the speed of the exhaust airflow, and generally the modified stainless steel exhaust pipe is about one-third lighter than the original product. And higher-level exhaust will use titanium alloy products (of course more expensive).

Titanium alloy, known as "space metal", has the characteristics of high strength, excellent corrosion resistance and heat resistance, and was originally used in the aviation field. Since the density of titanium alloy is only 60 of that of steel, but its strength is better, the exhaust pipe made of titanium alloy with the same strength is lighter than that of stainless steel (equivalent to half the weight of the original product). The weight of the car has made a great contribution, and it is suitable for car owners who pursue the ultimate lightweight modification. However, titanium alloy materials have higher requirements for welding, which is more difficult than ordinary steel materials. This is another reason for the higher price of titanium alloy exhaust pipes in addition to the cost of the material itself.

The sound quality of the exhaust pipes of the two materials is also different. The pipe wall of the titanium alloy exhaust pipe is very thin, so when the high-speed exhaust gas wave passes through, there will be a more smashing sound, which is sharper and slightly more piercing. Band loose. The sound of the stainless steel exhaust is relatively low-key and thick, unlike the style of the titanium alloy exhaust, the sound quality is low and thick. As for the timbre, radish and cabbage have their own preferences, it's entirely up to you to feel. In addition, the titanium alloy exhaust is also unique visually. The ultra-thin design of the exhaust pipe will show a unique blue appearance after being baked at a high temperature of the exhaust (for the sake of beauty, some stainless steel exhausts are now beginning to imitate Titanium alloy, intentionally made blue).

Recommended exhaust type for modification: street type original exhaust system

Compared with some competitive exhaust systems, the original street-type modified exhaust optimizes the entire exhaust system without changing the wiring of the chassis, which improves power output and makes installation more convenient. And the street-oriented design will not make the exhaust back pressure too low and extreme. At the same time, the exhaust system produced by GRWA can improve the performance and control the noise in a more reasonable range.

As a domestic exhaust system top modification brand, it is very trustworthy and a choice.

All GRWA products are on sale, welcome!

Any need, please feel free to consult us.