Hello.

After several loud shouts of "kurvaaaa !!!" with a motorcycle zapulivaniya in tree branches, the muffler on the poor TM EN 300 ... crumpled 🙂 I had to make a new one.

I would never have mastered such a job. Except for minor manipulations, such as burning a flute and traveling for materials, the new muffler can was completely made by Oleg, for which another huge thanks to him!

A muffler is one of the most common motorcycle tuning options. A logical question: why, besides the banal saving of money, bother with making a copy of the stock glushak, when you can order a tuned one, at the same time strangling the release a little. The fact is that the tuning of the release on two-stroke motorcycles should be started, first of all, with the resonator. And then to the resonator, which are selected for the desired operating speed range, select a muffler bank. Or not to pick it up, since it does not have such an effect on two-stroke, as on 4t. Therefore, ordering a tuned can of a muffler without tuning the resonator makes no sense, and ordering a stock is doubly meaningless. There is one more factor so as not to order FMF, Yoshka and similar products: there is so much foolishness in a two-stroke three hundred that, for example, I will not need to increase it additionally for many years 🙂

The original muffler on TM EN 300 is made of foil, it crumples perfectly, bending after another fall, starts to cling to the wheel when landing from jumps, when the suspension compresses - and wipes to holes!

Therefore, having sacrificed a little weight saving, a new muffler had to be made from an aluminum pipe 3 mm thick.

The pipe, however, was found with a diameter of only 100 mm, while in order to maintain the original proportions, the diameter of the pipe had to be 90 mm.

In parallel, I burned the flute. As it turned out, even a burner is not needed for this, a 400-degree building hair dryer will do.

In addition to saving motorcycle weight, no manufacturer will install mufflers with a 3 mm wall, or at least with 3 mm brackets for attaching to a subframe, on their motorcycles, since then this can will never break in its life, and the cost of materials will increase ...

The neat, scaly weld will be angled down towards the ground and not be seen. The turn came to make a plug made of 3 mm aluminum sheet. Then a tube will be welded into it, which will center and fix the flute from the inside.

Even with minimal scooter tuning, you need to think about installing resonant exhaust... The principle of operation and an overview of saxophones, as such mufflers are popularly called, we will give in another article.

Saxophone resonant muffler - the thing is not cheap and not everyone can afford it. Accordingly, scooters have a desire to save money and make such an exhaust pipe on their own. In this article, you will learn how to make a primitive homemade saxophone using a scooter as an example. Yamaha jog... Why primitive? Because with this method we will not lead resonator calculations (this requires a special program), but just use the drawing of the saxophone muffler.

Saxophone drawing on scooter

The drawing shows saxophone silencer dimensions on Yamaha Jog.

How to Make a Yamaha Jog Saxophone Muffler

So let's get started. For saxophone making we need metal, approximately 1.2 mm thick. It needs to be cut according to the dimensions indicated in the drawing (you can adjust these dimensions closer to your parameters). In order to accurately bend the metal, we grind a wooden blank according to the size (such a wooden muffler turned out to be) and already bend steel in this shape. After careful adjustment of the workpiece, we weld the joints with semi-automatic welding. We clean the part by any available means.

We also bend the muffler and the muffler pipe. On the one hand, we brew completely, and on the other hand, on rivets (to replace the filler, here is glass wool). After welding, we check all the elements for leaks - there should be no gaps, of course.

We grind and paint all the details. In this case muffler painted with powder paint and everything else with simple acrylic paint.

The mountings on the muffler are made of stainless steel.

And here is the result of our painstaking robots - a copy saxophone Tecnigas... Not bad, right?

Looks even better saxophone scooter.

After installing such a muffler, you may need to adjust the scooter carburetor, adjust the transmission as a whole and the engine in general.

Exhaust - motorcycle or scooter exhaust system

Text: Artem "S1LvER" Terekhov

The rumbling of a V-shaped line, the harsh howl of a sports Japanese rower, the unhurried rattling of an in-line British deuce ... These are the associations that an ordinary person has when he says "exhaust system". Designers and engineers see everything a little differently, from a harsh technical side. We will not go into deep jungle, but simply form an idea of \u200b\u200bhow the "exhalation" of our motorcycles works, and we will try to make it as interesting as possible.

Theory, theory ...

The main tasks that are set for the exhaust system are to remove the gases leaving the combustion chamber, cool them and reduce the noise level. Imagine what it would be like if hot exhaust flew out of the cylinder straight into the atmosphere! Of course, the front tire would melt together with the fender, and the engine noise level would become simply unbearable (for fun, try removing the exhaust system and starting the engine. Let's see how long your tender ears last). In addition, if there is a little unburned fuel left in the exhaust, it would effectively burn out upon contact with atmospheric oxygen. Therefore, the exhaust system directs the exhaust gases to the "tail" of the motorcycle, cooling them and eliminating unwanted combustion tendencies in the atmosphere.

Another task of the exhaust system is to use the pressure pulsations that are formed at each working stroke. This is done to improve cleaning and filling of the combustion chamber.

Usually the factory exhaust system is made of steel. Depending on the style requirements, the steel is chrome plated or painted with heat-resistant paint. Sometimes, although it is more expensive, stainless steel is used.

The bike also has a pulse

During each combustion stroke, high pressure waves are generated in the exhaust pipe as the gas moves. It is logical to assume that a high pressure wave is followed by a low pressure wave. At some point in the exhaust system, which is determined by the designers, part of the high pressure waves collide with the system, while the remaining high pressure wave leaves the pipe, the low pressure wave following it is reflected back. The low pressure wave fills the combustion chamber with a fresh air / fuel mixture. The reflected high pressure wave then prevents fresh mix from flowing out through the outlet. The next low pressure wave removes the exhaust gases from the combustion chamber. The process is repeated, the bike breathes smoothly and well.

The length of each pipe of the exhaust system is carefully calculated so that the pressure pulsations are at the required point at a given time. Correct exhausting plays a decisive role in high engine performance. Therefore, you should not buy "ends" of little-known basement firms. If you are already buying a tuning edition, do not spare money on a quality product from a reputable manufacturer.

The exhaust system is designed to perform best over a narrow engine speed range. Therefore, various systems are used to improve engine performance over the entire speed range, which we will discuss later.

Valves are everywhere! Even in exhaust systems

Outside certain speeds, the engine runs relatively inefficiently. Yamaha experts were the first to solve the problem, having developed the EXUP system (Exhaust Ultimate Power Valve, which in Russian means the monstrous "Absolute power valve of the exhaust system"). This design was the first mechanism for changing the internal section of the exhaust system, thus achieving maximum power over the entire range of engine operation. EXUP is located between the exhaust pipes and the muffler. The power valve is closed to medium speed, thereby reducing the pipe section, and open at high speeds, increasing the pipe section. It is controlled by the electronics and the servomotor. Interestingly, this mechanism was conceived as an additional means of reducing emissions, and was installed on the FZR1000 in the version for California, known for its tough eco-regulations. However, the engineers were surprised to find that the valve evens out the power response, and even slightly raises the horse population in the motor! After that, of course, EXUP began to be installed on many other bikes of the company, including the R1, MT-01 and FZ1.

The power valve is a special damper that partially overlaps the section of the exhaust pipe when the engine is resting at low and medium speeds to increase torque.

Later, solutions appeared from Suzuki called SET (Suzuki Exhaust Tuning), and from Honda - H-VIX (Honda Variable Intake \\ Exhaust). They are not fundamentally different from EXUP, only in the Honda version, separate valves in the exhaust pipes are used.

Two-stroke exhaust systems

The influence of exhaust on engine performance is much more significant here than on four-stroke (if it's not clear why, check out our article on this topic). A separate set of exhaust pipe and muffler, as well as a resonator is always installed on each cylinder.

The photo clearly shows the exhaust system with a resonator. Honda RS250R

The latter is optional, but allows a significant increase in power due to the natural tendencies of exhaust pulsations to resonate within the exhaust system. The system is designed in such a way that the exhaust pipe gradually merges into a straight muffler cone, at the end of which is a reverse cone, ending with a small exhaust pipe. A properly tuned resonator ensures the best filling of the cylinder with the working mixture, which means high power indicators. This effect is unattainable in any other way.

How it works

When the exhaust port is opened, gases are forced into the exhaust system, which is facilitated by the incoming fresh charge coming from the ports of the purge channel. The exhaust gases travel in the form of waves through the resonator, gradually expanding and losing speed. When the wave reaches the opposite cone, it contracts and is partially reflected back as a backward wave. The combustion chamber is at this point overfilled, and the excess mixture begins to fill the upper part of the exhaust pipe. As the piston closes the purge ports, the backwash reaches the exhaust port, returning excess mixture to the combustion chamber where it is trapped by the piston blocking the exhaust ports. In this way, a slight "boost" effect is achieved and the engine power is increased compared to normal conditions (that is, if the resonator were not present).

M. Coombs, "Motorcycles. Device and principle of action."

The optimal time for this effect to travel to the exhaust ports is achieved at a certain engine speed, above and below which the engine operates as usual. To take full advantage of this effect, careful tuning of the system is necessary - this is the only way to realize the additional power and the famous two-stroke "pickup". Two-stroke motorcycles will always have their own character - they live a short (in terms of working speed), but bright life. Power valves are also used on two-strokes (again, about this in our article), but the lot of 2T bikes are high-speed grips somewhere near the red zone.

Oh, those green ones!

We know from chemistry that a catalyst is a substance that initiates a chemical reaction between other elements, but does not itself participate in the reaction. I incited one to myself. That is, the catalyst is not consumed, and its properties do not change. The KH itself is maintenance-free, but it is very fragile and can be damaged if the exhaust system is faulty, or if leaded gasoline or the wrong air-fuel mixture is used. Leaded gasoline will clog the KH with deposits that no "domestos" will wash off.

Gold in pipes Kawasaki ZX-10R 2008

KH is a porous structure that is installed in the exhaust system. The catalysts are platinum, palladium and rhodium, which are used alone or in compounds. They sit there in order to literally "neutralize" harmful emissions in the exhaust gases, as a result of chemical reactions converting CH, CO and NO X into simple water vapor, carbon dioxide and oxygen. The porous KH is made in order not to create resistance to flow and to increase the surface area to ensure that all harmful emissions can react with the appropriate catalysts. And it is located exactly where it is located, because the reaction will take place only in a certain temperature range. In addition to the porous element, there is a chamber into which air is supplied, and in which reactions of converting harmful substances into harmless occur.

Catalyst, reaction chamber, clever silencer - the evil ZX-10R loves nature!

This is the real joy of the ecologist, but ordinary riders are clearly disadvantaged here. After all, the catalyst makes the system a couple of kilograms heavier, and steals some of the performance from the motor (although the KN is porous, but still it is much worse than if it simply was not there). It would seem - just take it and throw it away, it's just business! But no, the manufacturer puts electronic obstacles. For example, the latest GSX-R1000s have a sensor that monitors whether an adrenaline-hungry KN owner has ripped out of the exhaust system. If there is no catalyst, the engine simply will not start, only a light bulb will gloomily burn on the tidy. Conclusion: if you want to increase the number of notorious e-s, it is better to throw out the entire stock system, installing an aftermarket kit instead, and not forgetting to remove the annoying "glitch" in electronics. The tuning release will save weight and add power when properly tuned. I will modestly keep silent about the changed sound ...

And finally, the bank!

The exhaust system of the serial bike ends with a muffler. Its task is to ensure the maximum free passage of gases while simultaneously removing excess energy, which is noise.

This is usually achieved through absorption. The escaping gases are slowed down due to their expansion in the muffler housing. Further, the pulses are crushed when passing through a metal mesh and packing made of mineral wool or similar material. When they finally find a way out, they will more or less subside - the goal is achieved.

It is also possible to divide the muffler body into many small "tunnels" through which gases move in different directions along a rather winding path. Before leaving the exhaust pipe, sound waves are reflected repeatedly, thereby losing energy.
Typically, both approaches complement each other and find space on board the same motorcycle.

Such are the "vicissitudes" await noisy exhaust gases in the muffler liter Ninja.
The power valve is visible below, in this case located in front of the muffler.

Third-party muffler cans, which are designed to "improve sound and give a thousand horsepower," are essentially hollow tanks made of titanium, stainless steel, or carbon. There are no suppressing elements at all there, as well as increases in power. All you get is a modified sound, and not always for the better. It is worth knowing in advance how the bank you have your eye on "sings".

Making a forward flow

For this work we need:
1.two pipes:
1.muffler inlet pipe diameter (standard);
2.diameter d20 cm, length 1m;
2. old muffler VAZ 2109.

"We disassemble the old muffler. Cut out the walls, take out the insides (see Figure 1.).

"We take pipe 1.1., In the place where it will be in the muffler we drill holes (see figure 2.).

"From the side indicated by the arrow (see Figure 3.) weld pipe 1.2 onto it using a metal plate.

"We put this structure inside the body of the old muffler, and weld it on both sides (Fig. 4.)

"We wrap the muffler with a heat-resistant insulating plate (eg paronite).
"We wrap the muffler with a sheet of stainless steel with an overlap of 5 cm at each end and 5 cm in length. Stainless steel can be bought on the market. (Fig. 5.)

"We wrap the sidewalls and roll the joint. (Fig. 6)

"We weld the ears for the holders and mount the muffler in place.

About tuned exhaust

Article taken from the magazine "Tuning" St. Petersburg

Perhaps the most popular topic in all "smoking rooms", one way or another related to car tuning, is engine exhaust systems. At least I'm more likely to answer questions about emissions than about valves, heads, crankshafts and other components of engine tuning. Moreover, the range of questions is approximately the following: from "tell me, how to apply the formula for calculating the resonant frequency (the ratio for the Helmholtz resonator is given) to the four-throttle inlet?" before "a friend gave me a" spider "from his sports" golf ". How much horsepower will be added if I install it on my car?" or "I am building a motor for myself. What muffler should I buy for more power?", or "How much horsepower will be added if I install a resonator instead of a catalyst?" Moreover, in all matters, the additional power is the red line.

SO LET'S START BY LOOKING OUT WHERE THIS ADDITIONAL POWER IS. AND WHY THE EXHAUST LINE AFFECTS THE RUNNING OF THE MOTOR.

If we all unanimously understand that power is the product of torque and crankshaft rotation speed (revolutions), then it is clear that power is a speed-dependent quantity. Consider a purely theoretical engine (it does not matter if it is electric, internal combustion or turbojet), which gives a constant torque at speeds from 0 to infinity. (curve 2 in Fig. 1) Then its power will grow linearly with revolutions from 0 to infinity (curve 1 in Fig. 1). The subject of our interest is four-stroke multi-cylinder internal combustion engines, due to the design and processes occurring in them, have an increase in torque with an increase in revolutions to its maximum value, and with a further increase in revolutions, the torque drops again (curve 3 in Fig. 1). Then the power will have a similar form (curve 4 in Fig. 1). An important factor for understanding the functions of the exhaust system is the relationship between torque and cylinder filling ratio.

Figure: 1

Let's imagine the process taking place in the cylinder during the intake phase. Suppose the engine crankshaft rotates so slowly that we can observe the movement of the air-fuel mixture in the cylinder and at any time the pressure in the intake manifold and the cylinder has time to equalize. Suppose that the top dead center (TDC) pressure in the combustion chamber is equal to atmospheric pressure. Then, when the piston moves from TDC to bottom dead center (BDC), an amount of fresh air-fuel mixture, exactly equal to the volume of the cylinder, will enter the cylinder. They say that in this case the filling factor is equal to one. Suppose in the above process we close the intake valve at the piston position corresponding to 80% of its stroke. Then we will fill the cylinder only to 80% of its volume and the mass of the charge will be respectively 80%. The filling factor in this case will be 0.8. Another case. Suppose in some way we managed to create pressure 20% higher than atmospheric pressure in the intake manifold. Then, in the intake phase, we will be able to fill the cylinder by 120% by mass of the charge, which will correspond to a filling factor of 1.2. So, now the most important thing. The engine torque corresponds exactly to the cylinder fill factor on the torque curve. That is, the torque is higher there, where the filling ratio is higher, and exactly the same number of times, unless, of course, we do not take into account the internal losses in the engine, which grow with the rotation speed. From this it is clear that the torque curve and, accordingly, the power curve is determined by the dependence of the filling factor on the speed. We have the ability to influence, within certain limits, the dependence of the filling ratio on the engine speed by changing the valve timing. In general, without going into details, we can say that the wider the phases and the earlier we shift them in relation to the crankshaft, the maximum torque will be achieved at high revs. In this case, the absolute value of the maximum torque will be slightly less than with narrower phases (curve 5 in Fig. 1). The so-called overlap phase is essential. The fact is that at high rotational speed, the inertia of gases in the engine has a certain effect. For better filling at the end of the exhaust phase, the exhaust valve must be closed a little later than TDC, and the inlet valve must be opened much earlier than TDC. Then the engine has a state when in the TDC area with a minimum volume above the piston, both valves are open and the intake manifold communicates with the exhaust through the combustion chamber. This is a very important condition in terms of the effect of the exhaust system on engine performance. Now, I think it's time to look at the functions of the exhaust system. I must say right away that there are three processes in the exhaust system. The first is a more or less damped outflow of gases through pipes. The second is damping acoustic waves to reduce noise. And the third is the propagation of shock waves in a gas medium. We will consider any of these processes from the standpoint of its influence on the filling factor. Strictly speaking, we are interested in the pressure in the manifold at the exhaust valve at the time of its opening. It is clear that the lower the pressure, and better even below the atmospheric pressure, can be obtained, the greater the pressure drop from the intake manifold to the exhaust, the more charge the cylinder will receive in the intake phase. Let's start with some pretty obvious things. The exhaust pipe is used to direct exhaust gases outside the vehicle body. It is quite clear that it should not offer significant resistance to the flow. If, for some reason, a foreign object appears in the exhaust pipe, blocking the flow of gases (for example, the neighbors joked and shoved potatoes into the exhaust pipe), then the pressure in the exhaust pipe will not have time to drop, and when the exhaust valve is opened, the pressure in the manifold will oppose cleaning cylinder. The filling ratio will drop, since the remaining large amount of exhaust gases will not allow the cylinders to be filled with the same fresh mixture. Accordingly, the engine will not be able to generate the same torque. It is very important to understand that the dimensions of the pipe and the design of the noise mufflers in a production vehicle correspond fairly well to the amount of exhaust gases produced by the engine per unit of time. As soon as a serial engine has undergone changes in order to increase power (whether it is an increase in displacement or an increase in torque at high revs), the gas consumption through the exhaust pipe immediately increases and the question should be answered, does the serial exhaust system now create excessive resistance in the new conditions ... So from the consideration of the first process outlined by us, it should be concluded that the pipe sizes are sufficient. It is quite clear that after some reasonable size it is pointless to increase the pipe cross-section for a particular engine, there will be no improvement. And answering the question, where is the power, we can say that the main thing here is not to lose, it is impossible to acquire anything. From practice I can say that for a 1600 cc engine. cm, having a good torque up to 8000 rpm, a pipe with a diameter of 52 mm is sufficient. As soon as we talk about resistance in the exhaust system, it is necessary to mention such an important element as a silencer. Since in any case the muffler creates resistance to the flow, we can say that the best muffler is its complete absence. Unfortunately, for a road car, only desperate boors can afford it. Fighting noise is, no matter how you turn it, taking care of our health. Not only in everyday life, but also in motorsport, there are restrictions on the noise generated by the car engine. I must say that in most classes of sports cars exhaust noise is limited to 100 dB. These are quite loyal conditions, but without a muffler, no car will meet the technical requirements and will not be able to be admitted to the competition. Therefore, the choice of a silencer is always a compromise between its ability to absorb sound and low flow resistance.

NOW, PROBABLY, YOU SHOULD IMAGINE HOW THE SOUND IS EXTINGUISHED IN THE MUFFLER.

Acoustic waves (noise) carry energy that excites our hearing. The task of the muffler is to convert the vibration energy into thermal energy. Silencers should be divided into four groups according to the way they work. These are limiters, reflectors, resonators and absorbers.

LIMITER

The principle of its operation is simple. In the muffler body there is a significant narrowing of the pipe diameter, a certain acoustic resistance, and immediately behind it a large volume, an analogue of a container. Pressing sound through the resistance, we smooth out the oscillations with volume. The energy is dissipated in the choke, heating the gas. The higher the resistance (smaller the hole), the more effective the smoothing. But the greater the resistance to the flow. Probably a bad muffler. However, as a pre-silencer in the system, it is a fairly common design.

REFLECTOR

A large number of acoustic mirrors are organized in the muffler housing, from which sound waves are reflected. It is known that with each reflection, part of the energy is lost, spent on heating the mirror. If we arrange a whole labyrinth of mirrors for sound, then in the end we will dissipate almost all the energy and a very attenuated sound will come out. Pistol silencers are built on this principle. Much better design, however, since in the bowels of the hull we will also force the gas flow to change direction, we will still create some resistance to the exhaust gases. This design is most often used in end silencers of standard systems.

RESONATOR

Silencers of the resonator type use closed cavities located next to the pipeline and connected to it by a series of holes. Often in one case there are two unequal volumes, separated by a blind partition. Each hole, together with a closed cavity, is a resonator that excites natural frequency oscillations. The conditions of propagation of the resonant frequency change sharply, and it is effectively damped due to the friction of gas particles in the hole. Such mufflers effectively damp low frequencies in small sizes and are mainly used as preliminary, first in exhaust systems. They do not provide significant resistance to the flow, because the section is not reduced.

ABSORBER

The way the absorbers work is to absorb acoustic waves by some porous material. If we direct sound, for example, to glass wool, then it will cause vibrations of the fibers of the wool and friction of the fibers against each other. Thus, the sound vibrations will be converted into heat. Absorb li allow you to build a muffler structure without reducing the cross-section of the pipeline and even without bends, surrounding the pipe with holes cut in it with a layer of absorbing material. Such a muffler will have the lowest possible flow resistance, but it will reduce noise worst of all. I must say that serial exhaust systems use, in most cases, various combinations of all the above methods. There are two silencers in the system, and sometimes more. Attention should be paid to the peculiarity of the muffler designs, which, in the case of self-production, does not allow achieving effective noise reduction, although it seems that everything was done correctly. If there is no absorbing material inside the muffler, the walls of the housing become the source of sound. Many have noticed that some mufflers have an asbestos lining on the outside, pressed with an additional sheet of a false casing. This is the measure that will limit radiation through the walls and prevent heating of adjacent elements of the car. This measure is typical for the first and second types of mufflers. There is one more circumstance that cannot be ignored in the tuning article. This is the timbre of the sound. Often the client's wishes to the tuning company are to achieve a "noble" sound of the engine by replacing the muffler. It should be noted that if the requirements for the exhaust system do not extend beyond the change in "voice", then the task is greatly simplified. We can say that, most likely, an absorption-type muffler is more suitable for such purposes. Its volume, the amount of packing, as well as the packing itself determine the spectrum of frequencies that are intensely absorbed. Almost any soft padding absorbs more of the high-frequency component, giving a velvety sound. Silencers of the resonator type dampen low frequencies. Thus, by varying the size, content and set of elements, you can choose the timbre of the sound.

NOW YOU CAN GO TO THE MOST POPULAR AND MORE DIFFICULT QUESTION. HOW CAN THE ENGINE GET ADDITIONAL POWER THANKS TO THE EXHAUST SYSTEM ADJUSTMENT?

As we have already seen, fill ratio, torque and power are dependent on the pressure drop between the intake and exhaust manifolds during the purge phase. The exhaust system can be designed in such a way that shock waves propagating in the pipes, reflected from various elements of the system, will return to the exhaust valve in the form of a pressure surge or vacuum. Where does the vacuum come from, you ask. After all, we always only pump into the pipe and never suck it off. The fact is that, due to the inertia of gases, a pressure jump is always followed by a rarefaction front. It is the rarefaction front that interests us most of all. You just need to make sure that he is in the right place at the right time. We already know the place well. This is the outlet valve. And the time needs to be clarified. The fact is that the time of action of the front is very short. And the opening time of the exhaust valve, when the vacuum front can create useful work for us, strongly depends on the engine speed. And the entire period of the release phase must be divided into two components. The first is when the valve has just opened. This part is characterized by a large pressure drop and an active outflow of gases into the exhaust manifold. The exhaust gases leave the cylinder after the working stroke even without assistance. If the vacuum wave reaches the outlet valve at this point, it is unlikely to interfere with the cleaning process. But the end of the issue is more interesting. The pressure in the cylinder has already dropped to almost atmospheric. The piston is near TDC, which means that the volume above the piston is minimal. Moreover, the intake valve is already slightly open. Remember? This state (overlap phase) is characterized by the fact that the intake manifold communicates with the exhaust manifold through the combustion chamber. Now, if the front of decompression reaches the exhaust valve, we will be able to significantly improve the filling ratio, since even in a short time of action of the front, it will be possible to blow through a small volume of the combustion chamber and create a vacuum, which will help accelerate the air-fuel mixture in the intake manifold channel. And if we imagine that as soon as all the exhaust gases leave the cylinder, and the vacuum reaches its maximum value, the exhaust valve closes, we will be able to get a higher charge in the intake phase than if we cleaned the cylinder only to atmospheric pressure. This process of recharging the cylinders by using shock waves in the exhaust pipes can provide a high filling ratio and, as a result, additional power. The result of its action is approximately the same as if we pressurized the intake manifold using a compressor. After all, what difference does it make to how the differential pressure is created, pushing the fresh mixture into the combustion chamber, by means of injection from the intake side or vacuum in the cylinder? Such a process may well occur in the exhaust system of an internal combustion engine. There was a mere trifle. We need to organize such a process.

The first A necessary condition for recharging the cylinders with the help of shock waves is the existence of a sufficiently wide overlap phase. Strictly speaking, we are interested not so much in the phase width itself as a geometric value, but in the time interval when both valves are open. Without further explanation, it will be understood that with a constant phase, as the rotation speed increases, the time decreases. It automatically follows from this that when the exhaust system is tuned to certain revolutions, one of the variable parameters will be the width of the overlap phase. The higher the tuning speed, the wider the phase is needed. From practice, we can say that an overlap phase of less than 70 degrees will not allow for a noticeable effect, and the value for systems tuned to conventional 6000 rpm is 80 - 90 degrees.

Second the condition has already been defined. This is the need to return the shock wave to the outlet valve. Moreover, in multi-cylinder engines, it is not at all necessary to return it to the cylinder that generated it. Moreover, it is advantageous to return it, or rather, to use it in the next cylinder in the order of operation. The fact is that the speed of propagation of shock waves in the exhaust pipes is the speed of sound. In order to return the shock wave to the exhaust valve of the same cylinder, for example, at a speed of 6000 rpm, it is necessary to position the reflector at a distance of about 3.3 meters. The distance traveled by the shock wave during two revolutions of the crankshaft at this frequency is 6.6 meters. This is the path to the reflector and back. The reflector can be, for example, a sharp multiple increase in the area of \u200b\u200bthe pipe. The best option is to cut the pipe to atmosphere. Or, conversely, a decrease in the section in the form of a cone, a Laval nozzle, or, quite roughly, in the form of a washer. However, we agreed that we were not interested in various elements that reduce the cross section. Thus, tuned to 6000 rpm, the exhaust system of the proposed design for, for example, a four-cylinder engine will look like four pipes extending from the outlet ports of each cylinder, preferably straight, each 3.3 meters long. This design has a number of significant disadvantages. Firstly, it is unlikely that such a system can be placed under the body of, for example, a Golf 4 meters long or even an Audi A6 4.8 meters long. Again, a muffler is still needed. Then we must introduce the ends of four pipes into a jar of a sufficiently large volume, with acoustic characteristics close to an open atmosphere. From this jar it is necessary to remove the gas outlet pipe, which must be equipped with a silencer.

In short, this type of system is not suitable for a car. Although in fairness I must say that it is used on two-stroke four-cylinder motorcycle motors for circuit racing. For a two-stroke engine running at over 12,000 rpm, the pipe length is more than four times shorter to about 0.7 meters, which is quite reasonable even for a motorcycle.

Let's go back to our car engines. It is quite possible to reduce the geometric dimensions of the exhaust system, tuned to the same 6000 rpm, if we use a shock wave with the next cylinder in the order of operation. The release phase in it will begin for a three-cylinder engine after 240 degrees of crankshaft rotation, for a four-cylinder engine - after 180 degrees, for a six-cylinder engine - after 120 degrees and for an eight-cylinder engine - after 90 degrees. decreases and for, for example, a four-cylinder engine will be reduced by four times, which is 0.82 meters. The standard solution in this case is a well-known and desirable solution.<паук>... Its construction is simple. Four so-called primary pipes, which discharge gases from the cylinders, bending smoothly and approaching each other at a small angle, are connected into one secondary pipe having a cross-sectional area two to three times larger than one primary. The length from the exhaust valves to the junction is already known to us - for 6000 rpm about 820 mm. The work of such<паука> consists in the fact that the rarefaction jump following the shock wave, reaching the junction of all pipes, begins to propagate in the opposite direction into the other three pipes. In the next cylinder in the exhaust phase, the vacuum jump will do the work we need.

Here it must be said that the length of the secondary pipe also has a significant effect on the operation of the exhaust system. If the end of the secondary pipe is vented to atmosphere, then atmospheric pressure pulses will propagate in the secondary pipe against the impulses generated by the engine. The essence of adjusting the length of the secondary pipe is to avoid the simultaneous appearance of a vacuum pulse and a reverse atmospheric pressure pulse at the pipe junction. In practice, the length of the secondary pipe differs slightly from the length of the primary pipes. For systems that will have a further silencer, at the end of the secondary pipe, it is necessary to place the maximum volume and maximum cross-sectional area of \u200b\u200ba can with an absorbing coating inside. This bank should reproduce the acoustic characteristics of an infinite amount of airspace as best as possible. The elements of the exhaust system following this can, i.e. pipes and mufflers have no effect on the resonance properties of the exhaust system. We have already discussed their design, influence on flow resistance, on the level and timbre of noise. The lower the overpressure they provide, the better.

So, we have already considered two options for constructing an exhaust system tuned to certain revolutions, which, due to additional charging of the cylinders at resonance revolutions, increases the torque. These are four separate pipes for each cylinder and the so-called<паук> <четыре в один>... Mention should also be made of the option<два в один - два в один> or<два Y>, which is most often found in tuning cars, since it is easily assembled into standard bodies and does not differ too much in size and shape from the standard release. It is arranged quite simply. First, the pipes are connected in pairs from the first and fourth cylinders to one and the second and third to one as cylinders, equally spaced 180 degrees from each other along the crankshaft. The two formed pipes are also connected into one at a distance corresponding to the resonance frequency. The distance is measured from the valve along the centerline of the pipe. Paired primary pipes must be connected at a distance of one third of the total length. One of the frequently asked questions that have to be answered is what<паук> prefer. I must say right away that it is impossible to answer this question unequivocally. In some cases, a standard exhaust manifold with a standard downpipe works exactly the same. However, it is undoubtedly possible to compare the above three designs.

Here it is necessary to refer to such a concept as quality factor. Insofar as the tuned release is the essence of an oscillatory system, the resonant properties of which we use, it is clear that its quantitative characteristic - quality factor - may well be different. She's really different. The quality factor shows how many times the amplitude of the oscillations at the tuning frequency is greater than that far from it. The higher it is, the greater the pressure drop we can use, the better we will fill the cylinders and, accordingly, we will get an increase in torque. Since the quality factor is an energy characteristic, it is inextricably linked with the width of the resonant zone. Without going into details, we can say that if we get a big gain in torque, it will only be in a narrow rpm range for a high-quality system. And vice versa, if the range of revolutions, in which the improvement is achieved, is large, then the gain is insignificant, this is a low-quality system .. In Fig. 2, the vertical axis shows the pressure - vacuum obtained in the area of \u200b\u200bthe exhaust valve, and the horizontal axis - the engine speed. Curve 1 is typical for a high-Q system. In our case, these are four separate pipes, set at 6,000 rpm.

First. Since the torque is proportional to the pressure drop, high Q system number one will give the greatest gain. However, in a narrow rev range. A tuned engine with such a system will have a pronounced<подхват> in the resonance zone. And absolutely none at other speeds. The so-called single-mode or<самолетный> motor. Such an engine would most likely require a multi-stage transmission. In reality, such systems are not used in cars. The system of the second type has more<сглаженный> character, used mainly for circuit racing. The working rev range is much wider, the dips are less. But the momentum gain is also less. The engine tuned in this way is also not a gift, and there is no need to dream of elasticity. However, if the main thing is high speed while driving, then the transmission will be adjusted to this mode, and the pilot will master the control methods. The third type is even smoother. The working speed range is wide enough. The price to pay for this compliance is even less torque addition that can be obtained with the right setup. Such systems are used for rallies, in tuning for road cars. That is, for those cars that drive with frequent changes in driving modes. For which even torque is important in a wide rpm range.

Second. As always, there are no free gingerbread. At half the speed of the resonant frequency, the phase of the reflected wave will rotate 180 degrees, and instead of a vacuum jump in the overlap phase, a pressure wave will come to the exhaust valve, which will prevent blowing, that is, it will do the desired work in reverse. As a result, at half the speed, there will be a drop in torque, and the more we get at the top, the more we lose at the bottom. And no adjustments to the engine management system can compensate for this loss. It remains only to put up with this fact and operate the motor in the range that can be recognized<рабочим>.

However, humanity has come up with several ways to combat this phenomenon. One of them is electronically controlled dampers near the outlet holes in the head. The essence of their work is that at a low multiple of the frequency, the damper partially blocks the exhaust channel, preventing the propagation of shock waves and thereby destroying the resonance that has become harmful. Expressed more precisely, by many times reducing the quality factor. Reducing the cross-section due to closed flaps at low rpm is not so important as a small amount of exhaust gas is generated. The second way is the use of so-called collectors ... Their job is to offer little resistance to flow when the manifold pressure is less than the valve and increase resistance when the situation is reversed. The third way is the misalignment of the holes in the head and the manifold. The hole in the manifold is larger than in the head, coinciding along the upper edge with the hole in the head and not coinciding by about 1 - 2 mm along the bottom. The essence is the same as in the case of cone. From head to pipe -<по шерсти>, back -<против шерсти>... The last two options cannot be considered exhaustive due to the fact that<по шерсти> still somewhat worse than smooth pipes. As a lyrical digression, I can say that hole mismatch is a standard simple solution for many serial motors, which for some reason many<тюнингаторы> considered a defect in line production.

Third. Consequence of the second. If we tune the exhaust system to a resonant frequency, for example 4000 rpm, then at 8000 rpm we get the above<провал>if the system turns out to be operational at these speeds.

An important aspect when considering the operation of a tuned exhaust is the requirements for its design in terms of acoustic properties. First and foremost, there should be no other reflective elements in the system that will generate additional resonant frequencies that scatter the shock wave energy across the spectrum. This means that inside the pipes there should be no abrupt changes in the cross-sectional area, corners protruding inward and connection elements. Bending radii should be as large as the motor layout in the vehicle allows. All distances along the centerline of the pipe from the valve to the connection should be the same as possible.

The second important circumstance is that the shock wave carries energy. The higher the energy, the more useful work we can get from it. Temperature is a measure of gas energy. Therefore, it is better to insulate all pipes up to their junction. Usually the pipes are wrapped with heat-resistant, usually asbestos material and fixed to the pipe using bandages or steel wire.

Now, after the processes taking place in the exhaust system have become clear, it is quite possible to move on to practical recommendations for setting up exhaust systems. I must say right away that in such work you cannot rely on your feelings and it is necessary<вооружиться> measuring system. It must be measured by a direct or indirect method at least two parameters - torque and engine speed. It is clear that the best instrument is the engine dynamometer. Usually they do the following. An experimental exhaust system is made for the engine prepared for testing. Since the motor is on the stand and there are no restrictions in the pipe configuration due to the missing body, the simplest forms are quite applicable. The experimental system should be comfortable and as flexible as possible for changing its composition and pipe lengths. Various types of telescopic inserts give a good and quick result, allowing you to change the lengths of the elements within reasonable limits. If you want to get the most out of your propulsion system, you must be prepared to perform a significant amount of experimentation. Mathematical calculation and<попадание в яблочко> exclude from consideration the first time as an extremely unlikely event. It can be used like<приземление в заданном районе>... Some confidence that you are not far from the truth is given by experience and previous experiments with motors of similar characteristics, which have received good results.

Here, probably, it is necessary to stop and answer the question, and at what frequency should the exhaust system be tuned. To do this, you need to define a goal. Insofar as at the very beginning of the article we decided that we would achieve maximum power, then the best option in this sense is if we get an increase in torque on that part of the moment curve where the filling factor, and therefore the moment, begin to drop significantly due to high rotation speed, i.e. the power will stop growing. Then a small increase in torque will give a significant gain in power. See fig. 3. In order to find out this frequency, it is necessary at least to have the torque curve of the engine with unadjusted exhaust, ie, for example, with a standard manifold open to atmosphere. Of course, such experiments are very noisy and, excuse the harsh word, smelly, but necessary. Some hearing protection measures and good ventilation will provide the necessary data. Then, when we know the tuning frequency, we load the engine so that the rpm stabilizes at the desired point on the curve at 100% open throttle.

Now you can start experimenting with the different receiving pipes. The goal is to select such a front pipe or<паук>, or rather its length, in order to obtain an increase in torque at the desired frequency. When it hits the right point, the dynamometer will immediately respond with an increase in the measured force. The quickest result will be obtained by using telescopic tubes and changing the length with the engine running and loaded. Safety measures will be useful, since there is a possibility of burns, and an engine running at full load is dangerous in the sense of destruction. There are cases when, in an accident, fragments of a cylinder block pierced the body of a car and flew into the driver's cab. After the configuration is found<паука>, you can start setting up the secondary pipe in the same way. As I have already said, the influence of all other elements of the exhaust system is reduced to not losing what has already been achieved. Therefore, pipes and mufflers that are planned to be installed in a car should be docked to the first two elements found and adjusted and make sure that the settings are preserved or have not deteriorated significantly. Then you can already start designing and manufacturing a working system that will fit the car and will be located in the body tunnel intended for it. I must say that the work is very large and it is unlikely that it can be done without special equipment. In addition, it must be borne in mind that many factors affect the settings of the exhaust system. Smokey Yunick, a well-known authority in the field of sports engines in the United States, believes that the exhaust system, the intake and exhaust ports of the head, the shape of the combustion chamber, the valve timing (camshaft), the engine timing, the intake manifold, the power system and the ignition system are subject to joint tuning. He claims that any change in one of the named components necessarily entails a readjustment of all the others in order not to harm at worst, but at best to achieve greater motor efficiency. At a minimum, it is clear that in the overlap phase, when the tuned exhaust system is doing useful work, we are dealing with a through flow of gases from the intake to the exhaust manifold through the combustion chamber. The intake manifold, just like the exhaust system, can be viewed as an oscillatory speaker system with its own resonant properties. Since the purpose of tuning is to obtain the maximum pressure drop, the role of the intake manifold, or rather its geometry, is obvious. Its influence for motors with a wide phase of overlap may be less than from release due to lower energy, however, joint adjustment is absolutely necessary. For narrow-phase motors (read - serial), tuning the intake manifold is perhaps the only way to get resonant boost.

I would like to say a few words about the difference in the tuning of the injection and carburetor engines.

Firstly, the intake manifold design of an injection engine can be any, since we are not related to the design features of the carburetor, which means that the tuning options are much wider.

Secondly, at multiple frequencies, the negative effect of the reverse pressure drop is significantly lower. The carburetor sprays fuel for any movement of air in the diffuser. Therefore, multiple frequencies are characterized by an over-enrichment of the mixture due to the fact that the same volume of air first moves through the carburetor from the combustion chamber to the filter, and then back in the same cycle. In the case of an electronic injection system, the amount of fuel can be strictly adjusted using the control program. Also, a programmable ignition timing can help reduce the harmful effects of backwash at these rpm, not to mention the control of those exhaust flaps that have already been mentioned.

And third, the requirement for high-quality preparation of the mixture at low rpm dictates the need to use a narrowing section in the carburetor, known as a diffuser, which creates additional resistance to flow at high rpm.

For the sake of fairness, it must be said that horizontal twin carburetors Weber, Dellorto or Solex partially solve this problem, allowing each cylinder to give a pipe of the required length in order to adjust to the required speed, to have a sufficiently large cross section, but still cannot fight over-enrichment. There is another trick to improve the efficiency of the exhaust system. It is used mainly in tuning, since with certain aesthetic inclinations of the designer it allows you to create a catchy appearance of the car. Somewhere, at least in photographs of American car enthusiasts, you have probably seen cars with the ends of the exhaust pipes raised from under the rear bumper almost to the roof. The idea behind this design is that when driving behind the rear edge of the car, a<воздушный мешок>, or rarefaction zone. If we find the place where the vacuum is maximum, and the end of the exhaust pipe is placed at this point, then we will lower the level of static pressure inside the exhaust system. Accordingly, the static pressure level at the outlet valve will drop by the same amount. As long as the filling ratio is higher the lower the pressure at the outlet valve, this solution can be considered a good one.

In conclusion, I would like to say that despite the seeming simplicity, the installation of a different, different from the serial exhaust system, no matter how similar it may be to what is used in sports, does not at all guarantee your car additional horsepower. If you do not have the opportunity to make adjustments for your particular version of the motor, then the most reasonable way is that you buy a complete component for finalizing the motor from someone who has already performed these tests and knows the result in advance. The kit should likely include at least a camshaft, intake and exhaust manifolds, and a program for your ECU.

Hello!
A small topic on building a muffler "directly". An example is based on a moped, but it is no different from a car one. To do everything is real on the "knee" with a mallet in the barn, you just need to order a couple of parts to a familiar drunk turner and find a piece of stainless steel. my native factory is close at hand, where I have round-the-clock access to metals of various brands and machines. At the beginning we measure out which jar will be in size. The diameter is multiplied by 3.14 and we get the length of the circle in unfolded form, respectively. The diameter of mine is like 96mm and the height of the can is 400mm. Stainless steel it is better to take it in a film, for which you yourself will understand, but it will work without a film. We make a flat pipe and weld with spot welding.

Then the turner (I sharpened myself) turned 2 washers for us to the desired diameter.

And for what is the film on the pipe? For the inscriptions, of course!) For myself, I skimmed the Pasan pontovoy inscription ZiD Sport.

If there is no film, you can stick a wide electrical tape. First print the inscription on a printer, then glue it to the pipe and cut it with a scalp or special. Then he carefully removes the elements we don't need and voila, the stencil is ready.




We rejoice at the received inscription


Next, you need to make a pipe of the required diameter from a mesh or lattice with cells with a finger inside the muffler.


We insert all this so that the holes coincide with this pipe, we fill tightly around the edges with cotton wool such as Ursa or Knauf (these are construction heaters) Such wool can withstand a high enough temperature and does not fly out of the pipe due to the mesh inside. The middle remains completely free even if by shining a flashlight there, we will see the branch pipe even)
That's all, I got it all for free.

A motorcycle muffler is a device that attenuates the sound of an engine. Mufflers are needed not so much to reduce noise as to change the tone. And high-frequency sounds affect the psyche and ear of a person more unpleasantly than low tones.

Many associate the roar of sports motorcycles with a muffler. And they believe that filling the muffler can reduce the power of the car. But this is not the case. When replacing or redesigning a muffler, only a small amount of horsepower is lost.

There is an intake and exhaust muffler. And scientific research has proven that by choosing the right key elements, cylinder filling can be improved. Such mufflers are called resonant.

The part of the muffler located behind the first partition is engaged in noise suppression, and it consists of an acoustic filter. These filters are simpler on sport bikes, since a higher noise level is allowed in sport bikes.

When deciding to redesign a muffler, keep in mind the following. Sometimes, when improving one part, you have to sacrifice the quality of another. No one has yet succeeded in creating a universal motorcycle.

Manufacturers recommend using factory-made motorcycle mufflers. The muffler cavity is covered with carbon deposits, which can close the channels of the acoustic filter. Therefore, the cavity of the device must be cleaned regularly. Carbon deposits impede the escape of exhaust gases and reduce engine power. The mufflers need to be cleaned after every five to ten thousand kilometers.

The original mufflers are quite quiet and good. Their disadvantage is their heavy weight and size. Many also consider their high price to be a disadvantage. Silencers are manufactured by many companies, and you can use a non-native silencer if desired. Most often these are open mufflers. In them, the exhaust gases leave the engine without any obstruction. But they make a lot of noise.

Fans of a loud roar of motorcycles can buy the cheapest muffler that does not muffle anything. But if the roar of the motorcycle does not suit you, then you will have to buy an expensive option.

Such mufflers differ in design and material of manufacture. There are four types of them:

• Titanium. He is considered the best. It's lightweight, looks nice, and isn't very hot.
• Aluminum. Light enough. It looks worse than titanium, but there is a drawback. You can get severely burned.
• Carbon fiber. Looks beautiful, light and cold. But its significant drawback is that even with vibrations, it can crumble.
• Stainless steel. Strong and heavy, but very hot.

Each type of muffler has its own advantages and disadvantages. Therefore, you need to choose yourself.

You can buy a straight-through muffler at any specialized store. Usually they are interested in young motorcyclists who dream of high speeds. But real bikers are not bribed by famous brand stickers. They do everything they need with their own hands.

If there is a desire to enter the world for real men, you need to make a direct-flow muffler with your own hands. When riding at normal speed, its noise will not differ from other motorcycles. But with an increase in speed, the characteristic roar of the engine appears.
What do I need to do?

• A piece of pipe is taken, which has a diameter of 60 mm, and is cut in half. First, one piece is machined and a flange is welded in the middle. The outer part does not change. This is the inlet. In the half of the pipe, which will be located in the muffler, you need to drill a large number of holes with an electric drill. You need to use a drill of 5-6 mm. Sink the flange with a ten millimeter tip into the pipe with a diameter of 100 mm and weld it on.
• We are preparing the second pipe. Weld the flange to the second pipe section. It should be 80 mm from the edge. This part of the pipe will be inserted into the muffler.
• In a pipe with a diameter of 100 mm, carefully lay out mineral wool insulation. This is to combat noise reduction. To do this, roll the cotton wool along the diameter of the pipe and push it to the opposite side.
• Roll up the mesh and lower it inside the insulation that was inserted into the pipe. The mesh should slide over the perforated nipple.
• Now you need to insert a flange with a pipe that was prepared in advance into the pipe with the short end. It needs to be sunk 10 mm deep and welded.
• From the old muffler, you can cut off the fastening elements and transfer them to the straight-through muffler by welding them.

Why do motorcyclists need direct flow to a motorcycle

The exhaust system is designed to perform several tasks. Exhaust gases are removed. The exhaust outlet fills the engine cylinders better. And extinguishes the noises. The spent mixture is ejected from the cylinders at a very high speed and therefore a loud noise is generated. It is the muffler that reduces the noise of the exhaust gases due to the obstacles arranged in it.

A straight-through muffler simply does not have baffles that reduce noise. In this case, the exhaust gases escape without obstruction, and the engine power is increased. Therefore, the noise on these motorcycles is like a roar.

A straight-through muffler or a straight-through to a motorcycle makes a kind of engine roar and is not accepted by many people. It is believed that motorcycles with such a silencer disturb people and pollute the atmosphere.

Motorcyclists who advocate quiet city driving do not accept direct-flow mufflers. But experienced bikers are sure that forward flow is not only passive safety, but even active safety on the roads. Than? The fact that you can designate your location in the traffic.

Sometimes it is difficult even with a signal or headlights to show some drivers that you are nearby. And only the roar of the muffler helps to do this. And it happens that the sound of the muffler stops the driver from a careless maneuver that could lead to an accident.