DIY exhaust manifold

You can read a lot on the Internet about tuning the exhaust system of a VAZ with your own hands; many debates about the far-fetched or real increase in horsepower due to tuning the exhaust system stretch on to dozens of pages. Where is the truth?

Questions that are asked every time in similar topics:

Which muffler should I buy and install to get more power?
How much horsepower will be added if I mix the catalyst and install a resonator?
How will the motor power change if I install forward flow?

Purpose of the exhaust system

Reducing the concentration of pollutants in exhaust gases

Reducing exhaust noise levels

Main causes of breakdowns

In the exhaust system, especially of an old car with a lot of mileage, problems arise that are independent of the muffler material, so every driver should periodically inspect the entire system for cracks or burnouts. Timely maintenance will save the car owner from problems with replacing the exhaust manifold , which is very expensive.
The safety of the exhaust gas exhaust system is affected by:

exhaust gases having a high temperature;
aggressive mixtures;
vulnerability of the metal under high loads during operation.

The problems that arise are divided according to the design elements of the exhaust system:

The particulate filter (catalyst) serves to retain the soot contained in the exhaust gases, so the honeycomb segments become heavily clogged, and due to high temperatures the segments melt. Signs of problems - gases practically do not come out of the exhaust pipe or acrid bluish smoke appears.
Oxygen sensors - the housing is depressurized or overheated, wear and tear occurs, there is no contact in the electrical circuit of the machine, mechanical damage has occurred.
The corrugation in the muffler is a cylinder, inside of which there is a corrugated tube protected by a double braid, the top layer of which is made of stainless steel. The housing is elastic, therefore it dampens negative vibrations and prevents destruction of the entire system - rupture occurs due to a sharp increase in gas pressure when the catalyst is clogged.
The resonator is installed in front of the main muffler, so many car enthusiasts call it a small or additional similar element of the exhaust system. If the volume of gases escaping or vibrating sounds at the installation site of the resonator has increased, this indicates that one of the internal components of the product has burned out.
The muffler indicates that it needs to be repaired or urgently replaced by loud sounds when the internal combustion engine is running or a sharp drop in engine power, as well as strong vibration at the mounting location.
Exhaust manifold , if you smell exhaust gases in the cabin, it means that a crack has appeared on its body or the pipe has ruptured.

The damage described above also occurs from exposure to aggressive substances scattered on city streets to combat ice, for example, in the form of salt.

Exhaust system quality

Now about the concept of “quality factor”. Since the tuned outlet is an oscillatory system, its quantitative (quality factor) varies:

1. High-quality systems, when you can get a greater gain in torque, but only in a narrow range of revolutions (in reality, these systems are not used in cars).
2. Low-quality system, when the range of revolutions is larger, but the amount of gain is small (used in general for circuit racing).
3. Type 3 system, for those who need smooth torque over a wide range of speeds (used in rallies, in tuning for road cars).

“AR” manifoldElectronically controlled flaps near the outlet holes in the cylinder head. The damper partially blocks the exhaust channel, thereby preventing the spread of the shock wave and thereby destroying the resonance that has become harmful, reducing the quality factor.

The "AR" manifold exhibits little resistance when the manifold pressure is less than that of the valve, and increases resistance when the situation is reversed.

Mismatch of holes in the head and manifold (1 - 2 millimeters). The essence is the same as with an “AR” cone and this is a common solution for most production cars.

Muffler tuning

Owners often want a louder, sportier sound from their car. This can be achieved by installing a direct-flow muffler. Its design does not imply the presence of partition walls. Accordingly, gases will leave the system more freely. This will make it easier for the engine to “breathe” (the cylinder blowing will increase).

You can make such a muffler from a factory one. What do we need for this? You should prepare:

So, we remove the factory muffler and use a grinder to open its body. Next, we dismantle all its insides. After this, we make tree-shaped cuts along the entire perimeter of the new pipe. The length of the latter should be such that it fits in the body of the old muffler. By the way, holes can also be made using a drill.

The new pipe is welded to the remaining tails for welding. The remaining space must be filled with dishwashing sponges or glass wool. Next we close our cut out body. It needs to be brewed well so that gases do not leak through the seam. If desired, you can paint the muffler silver.

This completes the tuning of the exhaust system. Afterwards you can install the structure in place. Externally, such a muffler will look like a standard one. But at engine speeds above 3 thousand per minute, the car will make a loud and bassy sound.

Important points when adjusting the exhaust system

There should be no other reflective parts in the muffler system that give rise to new resonance. This means that there should be no sudden changes in cross-sectional area inside the pipes, corners or joint parts protruding inwards.

The shock wave carries energy within itself, which we transform into heat. It is better to insulate the pipes to the point of their connection (wrap them with heat-resistant asbestos material).

Use flexible connections. If the movement of the head of the motor module reaches 2-5 centimeters, then without flexible connections there will be constant breakthroughs in the hinged parts of the exhaust system and pipe breakage.

It would be correct to use a measuring system that will determine at least 2 parameters - torque and engine speed. Therefore, to adjust the exhaust system, a dynamometer for the engine will be appropriate. It is important to take into account that high-quality tuning of a car's exhaust is an expensive procedure.

As you can see, tuning the exhaust system is not as easy as it seems. Now you realize that changing the standard exhaust system to a sports one without properly modifying the intake does not guarantee additional auto. horses. If you can’t configure your engine, then the best solution would be not to stop at individual devices, but to purchase a complete engine tuning kit.

This set should already be configured. Most likely, the kit should include at a minimum the intake and exhaust manifolds, camshaft and ECU firmware.

The homelesscustomz channel continues, haters come))

In previous episodes you saw the gloomy stock exhaust manifold from H22a, with its cheerful diameter at the outlet and inlet. Those who haven’t seen it, come here As a result, it was decided to cook what I needed at random) I express my gratitude to Oleg from Nikolaev for measuring the RMF drag header and flanges, and davidos69 for 4-2 manifold drains) The Internet helped in the calculations and as a result I relied on this blogger (highly recommend watching)

After all the numbers, the next 4-1 was born, I didn’t want 4-2-1 for reasons - it had to be done)). For those interested in formulas, watch the video.

How to make a straight-through muffler quieter

The PG becomes quieter as it is collected. And each craftsman does this differently, using mineral wool, metal shavings, brushes or asbestos. It is also recommended to arrange several compartments inside the homemade muffler, creating additional resonance.

The installation of direct flow in various ways involves the use of mineral wool, shavings and other fillers

A car with an exhaust louder than 96 dB does not pass inspection, does not cross the border, and does not drive around the city. This is the law. Sound today is limited even in motorsport, where it would seem there should be no restrictions or boundaries.

Having decided to suppress the GHG, you need to understand that this should in no way affect the effectiveness of the new system. None of the components of the GHG system should create resistance to exhaust gases.

Flute

The flute or silencer in the PG is a simplified design used by tuners. Its task is to “calm down” the SG, obtaining legitimate dB at the output.

Making a flute is not difficult. It will be enough to use as a muffler a piece of a perforated 20-centimeter tube with a diameter that is slightly larger than the exhaust (by 1/3). A disk or conical washer must be fixed to the pipe to act as a plug. Fastening is carried out using bolts at the air cut. The washer, in fact, creates a structure that resembles a flute.

The flute is used in PG to reduce noise

The cost of ready-made silencers in stores varies from $8 to $150. Chinese models are very cheap, but don’t expect quality from them. Original, good European-made flutes can be purchased for $100–$150.

You can assemble a flute for the PG yourself. Below is a diagram by which you can easily make such a model.

A homemade flute is easy to assemble

A homemade flute is easy to assemble:

take a 20-centimeter steel pipe (it is recommended to use stainless steel) and a sheet of iron 1 mm thick;
welding is carried out (preferably arc);
Initially, a plug with holes for 8 bolts should be welded to the pipe.

It is recommended to fasten it with all 3 bolts, but you can do it with 1. It will be much faster.

Exhaust manifold: causes of failure and maintenance

Depending on the make of the car and the type of engine, models of various modifications are installed on the engine. They can be divided into two groups:

all-metal, they are usually made by casting iron;
tubular, for their production stainless pipes of various diameters are used.

The manifolds are attached to the internal combustion engine block using flanges. At each stroke, exhaust gases enter the chamber under pressure. Their temperature reaches 900 degrees. It is clear that a part operating in this mode can break.

A leak in the exhaust manifold is the most difficult defect. Possible situations:

one of the pipes burns out;
cracks appear on the collector due to dynamic load;
The pipe breaks off completely.

All this damage is a problem. For many cars, the procedure for replacing a part drags on for months - “original” spare parts sometimes have to be ordered.

Many service stations restore them. Welding of collectors, depending on their modification, is carried out using hot, cold or argon welding methods. The work is carried out using different types of equipment, using electrodes or filler wire. Restoration can be done in the courtyard or garage. How to weld the exhaust manifold yourself? Let's consider each of the methods in detail.

Thermal tape

This is another fairly common option for tuning the exhaust system of Audi and many other cars. What is its essence? The exhaust manifold gets very hot, and to prevent its walls from cooling down, the outer part is treated with thermal tape. Thus, at a consistently high temperature, gases will better leave the surface of the pipes, without turbulence. In total, the collector will take about five meters of such tape. It is wrapped in a spiral, as in the photo below.

Welding a cast iron exhaust manifold

Temperature processing of a high-carbon alloy is associated with certain difficulties:

carbon burns out when exposed to heat, the metal becomes friable;
Cast iron has a high fluidity coefficient;
upon rapid cooling, due to internal stress, the casting begins to crack and becomes whitish, this indicates a change in the structure of the alloy.

Welding a cast iron exhaust manifold can be done by trainees. It is better for beginners not to undertake the restoration of a car engine part, or they should first practice on junk cast iron products. Until recently, welders did not undertake repairs to cast iron. The seam turned out to have a high content of scale, and the metal cracked in the heating zone. After the advent of special copper-containing electrodes, which made it possible to reduce the temperature in the melt bath to +120°C, it became possible to create strong connections.

Types and design features of collectors

Structurally, all exhaust manifolds are divided into two large groups:

Solid;
Tubular.

One-piece manifolds are designed simply - they are a cast structure in which short pipes from each cylinder are combined into a common chamber or exhaust pipe. Due to the short length of the channels and the peculiarities of their location, such collectors have low efficiency and cannot be used to properly adjust the outlet. However, they are very simple to manufacture, so they are widely used on cheap engines and low-speed tractor diesel engines.

Often the one-piece manifold is combined into one unit with the intake manifold - this part is called a gas pipeline. This solution is widely used on domestic engines.

Tubular manifolds (they are often called “spiders” in our country) are a more complex design, but at the same time a more effective system with which you can fine-tune the exhaust. Such collectors are usually made of steel pipes, which at a certain length merge into a common receiving pipe.

Tubular collectors are divided into two large groups:

“Short” manifolds of type 4-1 - in such a manifold, the pipes from each cylinder are the same length and in one place converge into one exhaust pipe;
“Long” manifolds of the 4-2-1 type - in such a manifold the pipes are combined in pairs (usually the 1st and 4th, and the 2nd and 3rd cylinders are connected, they form a Y-shaped structure), and then two pairs are connected into one common receiving pipe.

These collectors are called "long" and "short" because of the path that the exhaust gases take. In 4-1 manifolds, gases travel a shorter distance, so they are better suited for high-speed engines (and they provide the best operating modes for engines with an operating shaft speed of 6000 rpm and above). In 4-2-1 manifolds, gases travel a longer path, so they are better suited for lower-speed engines and are widely used today.

Tubular collectors have characteristic shapes, for which they received the name “spider”. Such shapes are given to the collector pipes for a reason - the pipes coming out of each cylinder must have a strictly defined length, and so that all the pipes converge at one (for 4-1 collectors) or three (for 4-2-1 collectors) points, they have to be bent and twisted. The tightness of the engine compartment also plays a role here.

It is important to note that each engine must be equipped with a manifold designed for it, otherwise there will be a loss of power and deterioration in the performance of the power unit

Therefore, when boosting and tuning an engine, much attention is paid to the correct calculation and manufacture of manifolds for it. And with the right approach, using a collector alone, you can increase engine power by 3-5%

Welding a stainless steel manifold

Tubular components usually burn out at bends. Difficulties of working with stainless steel:

alloyed alloys in the working area are subject to temperature deformation;
Nickel, chromium, and other components actively oxidize when heated, which has a detrimental effect on the quality of the weld.

To eliminate defects, the argon welding method is used. The protective atmosphere protects the metal from oxidation; due to the airflow, the area bordering the working area heats up less. It must be taken into account that the thermal conductivity of stainless steel is lower than that of black low-carbon alloys. A small operating current is needed; it is selected experimentally. It is important to observe the speed of seam formation. The metal is welded in large passes so that intercrystalline corrosion does not occur in the joint area. The operating mode depends on the equipment used.

using a universal inverter, refractory tungsten electrodes are used for argon welding in CD/AC TIG mode;
for manual electric arc welding, heat-resistant MMA additives with a rutile coating are needed;
for semi-automatic machines, stainless steel wire is chosen; the seam is dense and does not require additional processing.

Making a sports muffler from scratch

Tuning the exhaust system can be done from scratch. For this we need:

The diameter of the pipes must be different. The outer one has a diameter of 13 centimeters, and the inner one is the standard 48 millimeters for a VAZ. If you are tuning the UAZ exhaust system, then this size is larger - 52 centimeters.

So, we take our perforated pipe and wrap it with non-flammable material. It could be asbestos. Next, install a large pipe and tightly fill the interior space with glass wool. After this, we use a welding machine to make seams on the front and back. It is important that everything is sealed. Next, we weld a hook for attaching the muffler in the bumper area. This hook should be both on the muffler itself and on the body. To secure it, you can take a regular rubber muffler cushion from a GAZelle. After this, you can safely install the element in place.

Cold welding when repairing the exhaust manifold

Small defects are repaired using special adhesives called “cold welding”. Before applying the mixture, the area to be repaired must be degreased. Adhesives should be used strictly according to the instructions. Then the result is a patch whose physical properties are similar to metal. This method is convenient for eliminating cracks and burnouts in hard-to-reach places. Glue is only a temporary measure to fix the damage. Under heavy loads of hot gases leaving the cylinders, the patched components will not last long. The adhesive composition is not designed for dynamic loads, but it can withstand static loads very well. Before purchasing glue, it is important to study its characteristics.