Exhaust modification, I want to be wild !

Someone asked "I like the sound of Maserati very much. If I install the exhaust of Maserati on my car, can I make a sound like Maserati?". This question is almost equivalent to "I like Taylor Swift's singing voice very much. If I buy a Sennheiser microphone or Shure KSM8 custom microphone, can I sing the same voice as Taylor?"

 For four-cylinder cars, it fire a total of 12,000 times at 6000 rpm; for V8 cars, it fire a total of 24,000 times at 6000 rpm, twice as much as four-cylinder cars. Not to mention those V10 and V12 that are close to ten thousand revolutions. Even if the exhaust system design is the same, the sound can not be the same. The timbre of solo singing and harmony is totally different.

Besides, the engine compartment space of a high-performance sports car is self-willed, and the exhaust manifold can be like musical instrument when it is opened.

And your scooter has limited engine compartment space, and the exhaust manifold can only grow like this, which looks like a blunt tool. Can the sound come out the same?

next question.

In this issue, let's talk about the modification of the exhaust. The original exhaust pipe made us "evil-minded" because it does have various restrictions.

The first and most important thing is environmental protection regulations, including emissions of pollutants, fuel economy and noise, all in the category of environmental protection. To "catch" the emission of pollutants, a three-way catalytic converter is necessary; to save fuel, a certain amount of exhaust resistance must be retained; to silence the sound waves (exhaust pipes are called mufflers in some contexts). This is all working against the modding players. Of course, it is not unreasonable to say that the modding players and the environmentalists are working against each other.

The second is to compromise on cost and body layout. The original exhaust is not willing to use a process that is costly and is not conducive to rapid mass production. If you can use castings, you absolutely don’t need welding parts. If you can use stamping parts, you don’t need CNC parts. Fish scale welding? nonexistent……

In addition, conditions such as maintaining the flatness of the chassis, leaving enough space for the drive shaft, suspension system, etc., will also cause the exhaust pipe to be bent and squashed, making the positioning and shape less than the ideal state.

At least the cost control of the modified exhaust is not so stingy, the output is not high, and the slow work is allowed. Some techniques that make the exhaust pipe look more delicate can be applied (such as beautiful fish scale welding and grilled blue tail mouth, etc.).

Therefore, with the condemnation and accusation of the stingy and compromising OEM, and the anger of the neighbors when we go home late at night, we must change the exhaust!

The modification of the exhaust system can achieve a series of effects, the change of the engine power curve (the loss of torque in exchange for high output), the increase of exhaust pollutant content, the change of exhaust loudness, tone color, and the look and feel of the exhaust system ( It's actually the exhaust tail throat). For the vast majority of people who change the exhaust, it can be summed up in just six words, just listen to it.

There is no need to expand the mouth specially. The design of the exhaust pipe, the pipe diameter, the thickness of the pipe wall, the internal structure of the tail drum, and the shape of the tail throat are almost zero in determining the performance of the exhaust pipe.

For an exhaust system of the same design, such as a pipe with a diameter of 55 mm, if you put a tail mouth as thick as a neck, or a Hello Kitty, the sound will not change significantly.

Focus on listening! Before that, let's talk about the cost of listening.

The principle of exhaust system noise reduction basically relies on "holding", holding the sound, the more you hold it, the quieter it becomes. So the louder the exhaust means the smoother, and the smoother the exhaust system, the smaller the internal resistance. The smaller the internal resistance, the easier the exhaust gas will be discharged. In the high-load and high-speed area, of course there is nothing wrong with doing this. However, in the low-load area of the engine, fresh air is properly mixed with some exhaust gas that has not yet been discharged, which will help improve fuel economy, reduce pumping losses, and improve low-torque response. So the louder the exhaust, the more terrible the low twist.

Why are sports cars loud and fast? That's because they are sports cars! Starting with a base displacement of 3.0, even if the low torque is weakened to 2.5, it is also 2.5; your 1.6 car, if the low torque is weakened to 1.2, it will not outperform Wuling Hongguang.

Simply put, loudness and low twist are negatively related. As a result, the desire of many people has become “to be loud without losing low twist”. All right, Party A wants colorful black, you know.

So various "back pressure tail drums" came into being. Through the circuitous design, let the exhaust gas travel a few more steps in the exhaust pipe, so that the effect of "blocking" the exhaust gas can be achieved; at the same time, the pipeline is entangled with noise-absorbing cotton. According to the density of the designed noise-absorbing cotton, Thickness, winding method, and exhaust gas path to adjust the exhaust sound.

Everyone visits refit shops and various cross-border refitting and accessories shops, and hears all kinds of "black words" such as "G drum", "H drum" and "S drum", which describe the direction of the pipeline inside the tail drum. For most people's rather pure conversion awareness of "but seeking a show", just replacing an exhaust tail section with a return pressure drum is enough.

Why do some exhaust drums cost a few hundred yuan, and some cost a few thousand yuan?

Expensive exhaust and cheap exhaust do not mean that the cheap ones are kind, and the expensive ones are profiteers. The reason why the prices of exhaust systems vary greatly. The first is the research and development cost of the exhaust system, whether the development and testing are sufficient, and whether there is fine "tuning" for the sound; the second is the materials used, including whether the main body is stainless steel or not. What kind of material is it? Is the soundproof cotton good? (bad soundproof cotton becomes a wig-like thing after a few months, and it doesn’t soundproof anymore), the welding process is not beautiful; does the brand have faith? and many more.

In fact, there are a lot of low-cost exhausts. Although the sound is loud, the Changan Stars whose exhaust pipes are rusted through the wholesale market are better than it. Generally speaking, you get what you pay for, but if you want to buy two cents, it will cost a dime.

Should I change the middle section and the first section?

The tail drum is just the "last one or two meters" of the exhaust. If you change the tail drum and feel that it is not noisy enough, then you have to play in the middle. The middle section of the exhaust, as the name suggests, is the transition section from the exhaust manifold of the engine to before the tail drum (especially the front engine).

In the middle section, the exhaust sound wave will also be reborn with the inner diameter of the exhaust pipe, the thickness of the pipe wall, and the design of the middle muffler drum. Because the exhaust middle section runs through the entire bottom of the passenger compartment, it is the main factor in the resonance between the low-speed exhaust system and the cabin. The middle section with poor design will become a kind of magical sound at a certain speed.

Take the example of modification around, Honda Party, 24K pure. I am obsessed with VTEC Sound, so I bought a full section of direct exhaust, which is shocking at any time. I know that a car that accelerates from 100 kilometers for 8 seconds is coming at full speed from 50 meters away. Listen to the loudness of the sound and know how far away it is.

However, the resonance is also very touching. When running at a high speed and the speed is maintained at around 3000rpm, the resonance makes one have to suspect that the body is shattered. Every day I get on the roller coaster with high frequency, and I am very tired. The buddy persisted for a few months, and broke up with the exhaust before his girlfriend broke up.

So, a good set of exhaust is not just light sound. The sound must have a texture, be durable, and try to suppress resonance in the middle. Why is expensive exhaust expensive? Because people's timbre is designed.

By the way, many "heavy flavors" (the peak power of turbocharged models are increased by more than 30%) power conversions require a middle section with a higher exhaust efficiency to cooperate. Conversely, if you only change the middle section without ECU adjustment, the power increase will not exceed 10%.

Replacing the exhaust manifold and head section is a more serious modification. At this time, the pursuit of "loudness" is basically no longer the pursuit, and the air resistance of the manifold/head section prevents the modifier from further tapping the potential of the engine. Strictly speaking, it is no longer a modification aimed at hearing. The owners who will change the manifold/head segment are already enthusiast players, so I won’t expand it here.

The red arrow is the thought of the girl talking, the yellow arrow.

The red arrow is the thought of girls talking, and the yellow arrow is the thought of boys talking (×). The red arrow is the quiet mode, and the yellow arrow is the rock mode.

A type of exhaust with a valve is very popular recently. The principle of this kind of exhaust is to set up two paths in a set of exhaust system, usually one is quiet and the other is noisy. The direction of exhaust gas flow is changed by opening and closing the valve, so as to freely switch between "silent" and "violent" modes.

At first, it was a coup of sports cars to avoid environmentalist rotten eggs, and later it was also popularized in the aftermarket, so that those who like to bomb the streets but not the communities have the best of both worlds. In addition to being expensive, complicated in structure, and having a certain chance of failure, it is the best exhaust modification solution.

Finally, ask for a Lingshuai with a 3000-rpm exhaust noise of 80 decibels. After being killed by a quiet Tesla P85D, the psychological shadow area of the Lingshuai owner. Lingshuai owner: The internal combustion engine is almost extinct, can I lie down even if I change the exhaust and listen to it?

In addition, which brand should I choose when purchasing modified accessories?

Let the following set of pictures illustrate it!