Since the middle of the 20th century, car manufacturers began to produce cars that are equipped with not one turbine, but two. One of the most popular such turbocharging systems is biturbo (Biturbo).
Let's look at why two turbochargers are installed. This contributes to:
- reduction of the turbo-jam effect;
- improve engine performance in transient conditions;
- greater profitability;
- the best environmental friendliness.
What does a biturbo look like (Biturbo)
Technically, the biturbo (bi-turbo) turbocharging system looks like this: a small turbine goes into a large one.
The principle of operation of the turbocharging system biturbo (Biturbo)
Biturbo (bi-turbo) - these are two series-connected turbines of different sizes. The system works as follows. At low speeds, a small turbine works. The larger one is connected when the number of revolutions of the motor increases.
This type of turbocharging system is also called sequential or sequential. That is, the turbines are put into operation one after another.
On low revs The engine is powered by a smaller turbine. It works constantly, providing traction even when the exhaust gas flow is low.
Gradually, the exhaust gases enter a large turbine. A large compressor slowly spins up, driving air through itself. At this point, the small compressor has a higher RPM. This provides excess pressure in the intake system. The higher the input, the higher the output.
It turns out that a small excess pressure is created at the inlet of the small compressor even when the large compressor is barely working. Under such conditions, the operating boost pressure is reached, the torque increases and the necessary volume of exhaust gases is created for the operation of the turbines.
On medium speed a small turbocharger reaches operating speed, its turbine rests on the limit of its capacity and performance. The big turbine is noticeably accelerating, but the potential is still there. The overpressure created by the large compressor is already quite noticeable. It enters the inlet of a small one, which compresses the mixture even more.
On high revs exhaust flow increases. The bypass valve of the smaller turbine opens slightly (this can also happen at medium speeds), and part of the exhaust gases enters directly into the large turbine. Now the large turbine is fully loaded, and the small one is, as it were, protected from twisting. Turbine and compressor parts continue to work fully.
If a vehicle is equipped with two turbochargers, very high boost pressures can be generated that cannot be achieved if only one compressor is running. And at this time, the driver will be able to accelerate smoothly, without jerks, since the effect of turbolag and turbolag is almost eliminated.
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BITURBO (BITURBO): WHAT IS IT AND PRINCIPLE OF WORK
Twinturbo and biturbo what is the difference and what are the differences
You have heard the names twinturbo (twinturbo) and biturbo (biturbo) more than once, but what is the difference? And there really is no difference! Twin turbo and bi-turbo are all marketing gimmicks and different names for the same turbo system. By the way, read the useful article by Kostya Neklyudin about the pros and cons of various turbocharging systems
Contrary to the beliefs of some "experts", the name of the biturbo or twinturbo system does not reflect the turbine operation scheme - parallel or sequential (sequential).
For example, in a Mitsubishi 3000 VR-4, the turbocharging system is called TwinTurbo (twinturbo). The car has a V6 engine and it has two turbines, each of which uses the energy of the exhaust gases from its three cylinders, but they blow into one common intake manifold. For example, German cars have systems similar in working principle, but they are not called twinturbo (twinturbo), but BiTurbo (BiTurbo).
Two turbines are installed on a Toyota Supra with an inline six, the turbocharging system is called TwinTurbo (twinturbo), but they work in a special sequence, turning on and off using special bypass valves. The Subaru B4 car also has two turbines, but they work in series: at low speeds, a small turbine blows, and at high speeds, when it fails, a second larger turbine is connected.
Let's now take a look at both bi-turbo (biturbo) and twinturbo (twinturbo) systems in order, or rather, what they write about them in "these of your Internets":
Bi-turbo (biturbo) - a turbocharging system, which consists of two turbines connected in series. The biturbo system uses two turbines, one small and the other larger. A small turbine spins faster, but at high engine speeds, a small turbine cannot cope with compressing the air and creating the right pressure. Then a large turbine is connected, adding a powerful charge of compressed air. Consequently, the delay (or turbolag) is minimized, and a smooth acceleration dynamics is formed. Biturbo systems are not a cheap pleasure and are usually installed on high-end cars.
The bitrubo system can be installed as on a V6 engine, where each turbine will be installed on its own side, but with a common intake. Either on an in-line engine, where the turbine is installed by cylinders (for example, 2 for a small and 2 for a large turbine), or sequentially, when a large pipe is first installed on the exhaust manifold, and then a small one.
Twin-turbo (twinturbo) - this system differs from bi-turbo in that it is not aimed at reducing turbo lag or equalizing acceleration dynamics, but at increasing performance. Twinturbo systems use two identical turbines, so the performance of such a turbocharging system is more efficient than systems with a single turbine. In addition, if you use 2 small turbines, similar in performance to one large one, you can reduce unwanted turbolag. But this does not mean that no one uses two large turbines. For example, a serious dredge might use two large turbines for even more performance. The twin-turbo system can operate on both V-engines and in-line engines. The sequence of turning on the turbines can vary, as in biturbo systems.
In general, for even more fun, no one bothers you to stick 3 (!) Turbines or more at once. The goal is the same as for twinturbo. I must say that this is often used in drag racing and never on stock cars.
By the way, read the useful article by Kostya Neklyudin about the pros and cons of various turbocharging systems
Do you like turbo or do you have a turbocharged car? Then join our group!
Turbocharging is often used on modern cars - it allows you to increase engine power by increasing the amount of fuel injected into the cylinder in one cycle. Since the middle of the 20th century, there have been cars that use two turbines at once - this arrangement is called Twinturbo, Biturbo, Double Turbo and other words. You can often find information about the fundamental differences between Twinturbo and Biturbo - separate articles provide definitions and the essence of unique structural elements. Let's try to understand the layout of these systems and we.
Turbocharging is increasingly used to increase engine power
The most interesting point in this problem is that there are no fundamental differences. Biturbo and its counterpart Twinturbo are simply alternative names for the same two-compressor supercharging systems. Moreover, both Biturbo and Twinturbo involve the use of various variations of the technical part.
Various names were coined by marketers of well-known car manufacturers to distinguish their products from the many similar cars built using the same layout. Interestingly, the Japanese prefer their Twinturbo twin turbochargers, while European companies write Biturbo - this has happened historically. Cars come to our country from both parts of the world, so both the name Biturbo and Twinturbo are familiar to domestic consumers. Therefore, the dispute about the differences between the names of turbochargers can be considered untenable - but it will be interesting to learn about fundamentally different systems used in international practice.
If you know what turbocharging is, then you will understand that installing two turbochargers has its own difficulties. Both turbines of the Biturbo system must be installed on the same exhaust line, and a certain distance must be maintained between them. The problem is that the long-range turbocharger will receive less power and not work as efficiently. In the middle of the 20th century, this problem was solved quite simply - the second turbine in the Twinturbo layout had different bearing characteristics and the shape of the impeller. Due to this, it was possible to synchronize the operation of the two units and significantly increase engine power using the Biturbo system.
The Biturbo system is used less and less
However, practice has shown that the sequential arrangement of Twinturbo has several important drawbacks:
- The presence of a serious "turbo lag", that is, a speed range in which the turbines simply do not work;
- Sufficiently long response time to gas supply;
- Accelerated wear of the near turbine;
- Inconvenience of installation on V-shaped motors.
They tried to solve the problem in various ways. However, the most elegant and efficient engineering solution came from Toyota, which included turbochargers in its Biturbo variant. At low revs, the valves are closed and the exhaust gases pass only through the small first turbine, easily spinning it and providing an early exit from the “turbo lag”. After reaching 3500 rpm, when the gas pressure is already becoming excessive, the electronics open a special damper, and the hot stream rushes to the second larger turbocharger, providing a significant increase in engine power.
However, with the mass distribution of V-shaped motors, the sequential Biturbo system began to be used less and less, since it was inconvenient to use it from a constructive point of view. Around the beginning of the 80s, an alternative Twinturbo layout was proposed, in which each turbine was assigned to several engine cylinders - as a rule, it was about one or another "half" of the block. Turbochargers could be located much closer to the intake and exhaust manifolds, which significantly reduced the level of mechanical and aerodynamic losses, and also increased engine power. In addition, the parallel Biturbo system, using compact turbines, made it possible to get rid of "turbo lag" and make the engine very sensitive to changes in fuel supply.
In most cases, the Twin Turbo parallel circuit uses a common intake manifold, which simplifies it and makes it less expensive to maintain, but limits the dynamic potential of the car. Therefore, as an alternative, a Biturbo layout with separate intake tracts and manifolds was proposed. Among other things, this made it possible to adapt the system for use on compact in-line engines, which were previously equipped exclusively with two turbochargers arranged in series.
However, the most interesting Twinturbo scheme was proposed by BMW - its difference was the location of the turbines in the V8 camber, and not on the sides of the cylinder block. Moreover, each of the turbochargers was powered by cylinders located on both sides of the engine! Despite the enormous difficulties that the engineers had to overcome, the result exceeded all expectations. Such an original Biturbo system reduced the length of the “turbo-jam” by 40% without compromising the reliability of the assembly. In addition, the stability of the engine has significantly increased and the intensity of its vibrations has decreased.
Sometimes the Twinscroll turbine is confused with the Twinturbo layout. The latter involves the use of one turbine, which has two channels and two sections of the impeller with different blade shapes. At low speeds, a valve opens leading to a smaller impeller - as a result, the turbocharger accelerates quickly enough and provides an increase in power without "turbo lag". However, with an increase in the speed of rotation of the crankshaft, the pressure of the exhaust gases becomes excessive and the second valve opens - now only the large impeller is used. As a result, the car receives an additional increase in performance.
Of course, such a system has a slightly lower efficiency than the classic Biturbo. However, in comparison with a single turbine, the traction capabilities of the engine still increase. Of course, the Twinscroll layout is difficult to manufacture and is considered quite unreliable. However, at present it is very often used in powerful cars - including as part of the Biturbo system.
If you know how a mechanical compressor differs from a turbine, then you will understand why these two systems are considered incompatible - the first is driven by the crankshaft, while the turbocharger uses the energy of the exhaust gases and it is almost impossible to combine them. However, nothing is impossible for Volkswagen engineers - they included both nodes in their version of the Twinturbo system. The turbine runs constantly, while the compressor helps eliminate "turbo lag" at low revs. Subsequently, it turns off, but when the gas pedal is pressed sharply, it again comes into action, improving the engine's response to fuel supply.
The result of using this Biturbo variant was a significant increase in power, reaching the limit of torque at low speeds, accelerating acceleration, as well as reducing the response time to pressing the gas pedal. The difference with a simple Twinturbo is almost imperceptible for the driver - he only feels the easily predictable powerful dynamics and is not distracted by power failures or other problems. However, the system developed by Volkswagen proved to be very difficult to manufacture and unreliable. Therefore, at present, only one of the two boost options is used on cars of brands that are part of the group of companies.
Summarizing the above, we can conclude that the differences between Twinturbo and Biturbo are only in the name. If you are really interested in different boost systems, you should look into parallel and series layouts. In addition, it would be useful to familiarize yourself in more detail with the differences between a turbocharger and mechanical supercharging and the advantages of their combined use.
How do Biturbo and Twin Turbo engines work in cars?
Literally translated from English, the phrase twin-turbo means "double turbo" or "double turbo". Both translations are correct. Now let's leave the linguistic aspect and study in detail the technical side of this type of turbocharging.
In order to achieve a noticeable increase in engine power, a turbine is installed in its design. Twin-Turbo is one of the types of a car's turbo system and it is on it that we will focus our attention. Twin turbo implies the installation of two identical turbines at once, which greatly increase the performance of the entire turbocharging system. This arrangement is much more efficient than a turbo system, which uses only one turbine.
Initially, the biturbo was designed to solve the main problem of all inflatable engines - the elimination of the so-called "turbo lag". This phenomenon is manifested in a decrease in elasticity and a sharp drop in engine power at low revs. All this happens at a time when the engine turbine under the pressure of the exhaust gases does not have time to spin up to the optimum speed.
Subsequently, it was noticed that twin turbines allow a significant increase in the range of revolutions of the rated torque, thereby increasing the maximum power, while reducing overall fuel consumption.
Did you know? The exclusive Bugatti Veyron supercar is equipped with four turbines at once, and such a turbocharging system has received the corresponding name - Quad-Turbo.
There are several main types of Twin-Turbo system: parallel, sequential and stepped. Each type of turbocharging is characterized by its own geometry, operating principle and outstanding dynamic characteristics.
This is a relatively simple type of turbo system, the design of which includes a symmetrical pair of simultaneously operating compressors. Thanks to this synchronization, a uniform distribution of the incoming air is achieved.
Often this scheme is used in diesel V-shaped engines, where each compressor is responsible for supplying air to the intake manifold of its cylinder group.
Reducing inertia is achieved by reducing the mass of the turbine rotor, since 2 small compressors create more pressure, while spinning up much faster than one large and more efficient compressor. As a result, the turbo lag mentioned above is significantly reduced, and the engine produces better performance throughout the entire rev range.
This type implies an arrangement consisting of two commensurate compressors, which, at the same time, can have different characteristics and work in a complementary mode. The lighter, faster supercharger operates continuously, eliminating deep and wide turbo lag. The second supercharger, using special electronic signals, controls the engine speed and turns on at heavier engine operating conditions, thus ensuring maximum power and fuel efficiency.
At peak engine operating conditions, 2 turbines are switched on at once, working in pairs. A similar scheme can be applied to engines with any fuel cycle.
The most sophisticated and advanced type of turbocharging, providing the widest powerband. The creation of the necessary pressurization becomes possible thanks to the installation of two compressors of different sizes, interconnected by a special system of bypass valves and pipes.
This type of turbocharging is called staged due to the fact that the exhaust gases in the minimum modes spin a small turbine, and this allows the engine to easily pick up speed and work with greater efficiency. As the speed increases, the valve opens, which in turn sets the large turbine in motion. But the pressure that it creates must be increased, which is what the small turbine does.
After reaching maximum speed, the large turbine produces enormous pressure, which turns the small supercharger into aerodynamic drag. At this very moment, the automation opens the bypass valve, and compressed air enters the engine, bypassing a small turbine in its path.
But all the complexity of this system is fully offset by the flexibility of the engine and its highest performance.
What are the advantages of using Twin-Turbo and are there any disadvantages
The undoubted advantage of the Twin Turbo system is high power with a relatively small engine displacement. This also includes the high torque and excellent dynamics of a car equipped with Twin-Turbo. A twin-turbo engine is much more environmentally friendly than a conventional engine, since the turbocharger allows the fuel to burn much more efficiently in the cylinder system.
Among the disadvantages of biturbo, one can single out the complexity of operating such a system. The power plant becomes more sensitive to the quality of fuel and engine oil. Turbocharged engines need a special oil, because without it the service life of the oil filter is noticeably reduced. The high temperatures in which the turbines operate adversely affect the entire engine of the car.
The main disadvantage of the Twin-Turbo system is the high fuel consumption. To create an air-fuel mixture in the cylinders, a large volume of air is required, which entails an increase in the fuel supply.
Turbines wear out pretty quickly if you immediately turn off the engine when you stop the car. To prolong the life of the Twin-Turbo, you should let the engine idle for some time, thus cooling the turbines, and only after that you can safely get the ignition key.
Remember! Twin-Turbo is a complex and very sensitive turbocharging system that needs careful handling and quality components. Compliance with these simple rules allows you to enjoy the speed and dynamics of the car to the maximum.
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Bi-turbo (Bi-Turbo) and Twin-turbo (Twin-Turbo), dual supercharging - differences. So different or not?
Turbocharged engines are not as simple as they seem, there are many misunderstandings and uncertainties around this topic. One of these is about two buildings "bi-turbo" and "twin-turbo". Not so long ago, he personally witnessed a conversation between two car owners, one assured that there was a difference, but the other - that there were no differences! So what is the truth? Indeed, what is the difference between these two structures of TURBO engines, let's figure it out ...
To be honest, there will be a difference, of course, but it will not be categorical! Only because the names are taken from different manufacturers who install their units with different layouts and structures.
However, the Bi-Turbo and Twin-Turbo systems are essentially the same thing. If you take English and look at the designation, Bi-Turbo and Twin-Turbo, you can see two prefixes "Bi" and "Twin" - if roughly translated, it turns out - "TWO" or "TWO". Nothing more than a designation for the presence of two turbines on an engine, and one and the other name can be applied to the same engine, that is, they are absolutely interchangeable. These names do not carry any technical differences, so this is "naked marketing".
Now the question may arise, why at all? It's just that there are only two questions that they are designed to solve:
- Eliminating the turbo lag, we can say that this is a priority problem.
- Power increase.
- Engine structure.
I'll start, perhaps, with the simplest point - this is the structure of the engine. Of course, it's easy to fit one turbo when you have a 4 or 6 cylinder inline engine. There is only one muffler. But what to do when you have, say, a V-shaped motor? And three or four cylinders on each side, then two mufflers! So they put on each turbine, medium or low power.
Eliminating the turbo lag - as I wrote above, this is task number "1". The thing is that a turbocharged engine has a failure - when you press the gas, the exhaust gases need to go through and spin the turbine impeller, it is this time that the power “sags”, it can be from 2 to 3 seconds! And if you need to make an overtaking maneuver at speed, it's not safe! So they install various turbines, and often a compressor + turbine. One works at low speeds, that is, at the start, in order to avoid "turbo lag", the second - at a speed when you need to leave traction.
Increasing power is the most commonplace case. That is, to increase the power of the motor, another powerful one is installed to a low-power turbine, thus two of them blow, which significantly increases productivity. By the way, on some racing cars, there are three or even four turbines, but this is very difficult and, as a rule, does not go into series!
Here are the solutions for which TWINTURBO or BITURBO are used, and you know this is really a way out of getting rid of the turbo lag and increasing power.
Now, on many cars, only two main structures are used - the location of two turbines. This is parallel and sequential (also known as sequential).
For example, some Mitsubishis have exactly “TWINTURBO”, but parallel operation, as I noted above, these are two turbines on the V6 unit, one for each side. They blow into a common collector. But for example, on some AUDIs, there is also parallel operation on the V6 engine, but the name is "BITURBO".
On Toyota cars, in particular on SUPRA, there is an in-line six, but there are also two boosters - they work in a tricky manner, two can work at once, one can work, the other does not, they can turn on alternately. It all depends on your driving style - they achieve such work with "cunning" bypass valves. That's serial-parallel work for you.
As on some SUBARU cars - the first (small) pumps air at low revs, the second (large) is connected only when the revs have increased significantly, here you have a parallel connection.
So is there a difference or is there no difference at all? You know behind the scenes, manufacturers still distinguish between these two buildings, let's take a closer look.
As a rule, these are two turbines connected in series to work. On a vivid example of SUBARU - one small and then another large.
The small one spins up much faster, because it does not have a lot of inertial energy - it is logical that it is included in the work on the bottom, that is, the first one. For low speeds and up to low speeds, this is quite enough. But at high speeds and revolutions, this "baby" is practically useless, here you need a supply of a much larger volume of compressed air - the second, heavier and more powerful turbine is turned on. Which gives the necessary power and performance. What gives such a consistent placement in BI-TURBO? It's almost turbo-lag exception (comfortable acceleration) and high performance at high speeds where traction remains even at speeds over 200 km/h.
It should be noted that they can be installed both on a V6 unit (with its own turbine on each side), and on an in-line version (the exhaust manifold can be divided here, for example, one blows from two cylinders, and another from the other two).
The disadvantages are the high cost and work on setting up such a system. After all, fine adjustments of bypass valves are used here. Therefore, the installation is conditioned on expensive sports cars, such as TOYOTA SUPRA, or on an elite class car - MASERATTI, ASTON MARTIN, etc.
Here, the main task is not to get rid of the “turbo lag”, but to maximize productivity (injection of compressed air). As a rule, such a system works at high speeds, when one supercharger cannot cope with the increased load on it, so another one of the same is installed (in parallel). Together they pump twice as much air for nearly the same performance boost!
But what about the "turbo-jam" that it rages here? But no, it is also effectively defeated only in a slightly different way. As I said, small turbines spin up much faster, so imagine - they change 1 large one, for 2 small ones - the performance practically does not drop (they work in parallel), but the PIT goes away because the reaction is faster. Therefore, it turns out, to create normal traction, from the very bottom.
Installation can be both on in-line models of power units, and on V-shaped ones.
It is much cheaper to manufacture and set up, so this structure is used by many manufacturers.
You can also call it "BI-TURBO" or "TWIN-TURBO" - whatever you want. In fact, both the compressor and the turbo version do the same job, only one (mechanical) is much more efficient at the bottom, the other (from exhaust gases) at the top! Read about the differences in boosts here.
As a rule, the compressor is mounted on a belt drive from the engine crankshaft, so it spins up with it as quickly as possible. Thus, allowing you to avoid the "PIT", but at high speeds it is useless - this is where the turbo option comes in.
This symbiosis is used on some German cars, a big plus of the compressor is that it has a much higher resource than the opponent!
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The car is valued not only for build quality and design, but also for speed. allows you to achieve new opportunities from the vehicle, so drivers often think about increasing the speed in their car. A popular method is to use twin turbos and biturbos, but is there a difference between the two?
Essence of the question
Many modern cars use these to increase their fuel use. Due to the larger amount of injected fuel, the overall speed increases. The real technology was known back in the 20th century - the layout of the two pipes was called Double Turbo, Twin-turbo and so on. Today they are presented as twin-turbo and bi-turbo technologies.
What does it mean
Biturbo is a turbocharging design that looks like two turbines. The first of them is large, and the second is reduced. While the former adds powerful airflow, the smaller turbine serves as the main element for mid-speed operation. Such a system is aimed at smoother operation of the accelerated movement.
The twin-turbo design is more focused on power gains than vehicle stability. For this reason, it uses two identical turbines that directly affect the speed of movement.
Layout differences
According to the manufacturers, there is a big difference between these systems. In fact, there are no significant differences in technology. This is a successful marketing move that has a positive effect on product sales. Biturbo and twin-turbo are able to use different technological variations in the form of different sizes of turbines, therefore they are universal systems.
For example, turbocharging in many cars is called twin-turbo (Mitsubishi 3000 VR-4). At the same time, in a V6 car, which has two turbines for three cylinders that use the exhaust gas flow. There are also similar systems in German production, but they are called Biturbo.
As practice shows, the Japanese use twin-turbo to a greater extent, when biturbo is more popular in Europe. In our country, you can purchase both variations with different technological features.
Classic variant
Twin turbo technology means that two compressors are used. There is a rather big difficulty with the installation of two exhaust pipes on one line, since there must be space between them. A frequent problem is the unequal distribution of energy between the two compressors. This disadvantage was solved by the original shape of the twin-turbo turbine in the form of an impeller, which synchronized the operation of the entire device.
The layout features of the twin-turbo system are some disadvantages:
- the presence of the so-called "turbo-jam", in which the turbines do not work;
- the near turbine receives accelerated wear;
- gas supply is slow;
- difficult installation for V-type motors.
Toyota offered its own solution to these problems - it made its own version for biturbo turbochargers. At low speeds, the valves of the product are closed, so the exhaust gases exit through the first turbine. It, in turn, quickly spins up and allows you to bypass the “turbo lag” at an early stage. When the movement reaches 3500 rpm, the engine opens special valves for excess gas, causing all the hot air to be redirected to the turbocharger, significantly increasing engine power.
Modern look
The biturbo system has become less used, because V-motors have become widespread. It turned out to be inconvenient due to its design features. In the 80s, a system was introduced with the turbine fastened behind the cylinders. This allowed the turbochargers to be mounted closer to the manifolds to reduce aerodynamic losses and improve overall speed. It also improved the overall stability of the system.
Assembly Features
Most often, the twin-turbo system allows the use of a single intake manifold, which is why maintenance costs are somewhat reduced, although decreasing. To compensate for this, separate manifolds and intake tracts were used. This made it possible to use the system for small engines, on which the turbochargers were always placed in series.
BMW has its own vision for twin-turbo technology - the location of the turbines was in the camber of the V8, and not on the sides, as usual. The main feature was that the compressors were powered by cylinders that were located on both sides. Thanks to this solution, the "turbo lag" was reduced by 40% without significant loss of power. In addition, it reduced vibrations from the operation of the equipment.
It is not necessary for the average car user to know the difference between twin-turbo and bi-turbo, because these systems are as similar as possible. The peculiarity in variations in the size of the turbines and the sequence of their connection makes these designs universal. The twin-turbo is more focused on convenience and ride comfort, while the biturbo is presented as a more powerful system. Their assembly can change based on requirements, so you can choose any of these systems.
If you have heard about biturbo and twin-turbo technologies, but do not know which one is better to choose, you should pay attention to the technical part of the car. Most often, all the differences between the systems are presented only in the name.
Literally translated from English, the phrase twin-turbo means "double turbo" or "double turbo". Both translations are correct. Now let's leave the linguistic aspect and study in detail the technical side of this type of turbocharging.
What is Twin-Turbo (Twin turbo)
In order to achieve a noticeable increase in engine power, a turbine is installed in its design. Twin-Turbo is one of the types of a car's turbo system and it is on it that we will focus our attention. Twin turbo implies installation two identical turbines at once, which greatly increase the performance of the entire turbocharging system. This arrangement is much more efficient than a turbo system, which uses only one turbine.
Initially, the biturbo was designed to solve the main problem of all inflatable engines - elimination of the so-called "turbojama". This phenomenon is manifested in a decrease in elasticity and a sharp drop in engine power at low revs. All this happens at a time when the engine turbine under the pressure of the exhaust gases does not have time to spin up to the optimum speed.
Subsequently, it was noticed that twin turbines allow a significant increase in the range of revolutions of the rated torque, thereby increasing the maximum power, while reducing overall fuel consumption.
Did you know?The exclusive supercar Bugatti Veyron is equipped with four turbines at once, and such a turbocharging system has received the corresponding name - Quad-Turbo.
Types of turbocharging systems and their principle of operation
There are several main types of Twin-Turbo system: parallel, series and step. Each type of turbocharging is characterized by its own geometry, operating principle and outstanding dynamic characteristics.
Parallel
This is a relatively simple type of turbo system, the design of which includes symmetrical pair of simultaneously operating compressors. Thanks to this synchronization, a uniform distribution of the incoming air is achieved.
Often this scheme is used in diesel V-shaped engines, where each compressor is responsible for supplying air to the intake manifold of its cylinder group.
Reducing inertia is achieved by reducing the mass of the turbine rotor, since 2 small compressors create more pressure, while spinning up much faster than one large and more efficient compressor. As a result, the turbo lag mentioned above is significantly reduced, and the engine produces better performance throughout the entire rev range.
Consistent
This type implies a layout consisting of two comparable compressors, which can have different characteristics and work in complementary mode. The lighter, faster supercharger operates continuously, eliminating deep and wide turbo lag. The second supercharger, using special electronic signals, controls the engine speed and turns on at heavier engine operating conditions, thus ensuring maximum power and fuel efficiency.
At peak engine operating conditions, 2 turbines are switched on at once, working in pairs. A similar scheme can be applied to engines with any fuel cycle.
stepped
The most sophisticated and advanced type of turbocharging, providing the widest powerband. The creation of the necessary pressurization becomes possible thanks to the installation two different-sized compressors interconnected by a special system of bypass valves and nozzles.
This type of turbocharging is called staged due to the fact that the exhaust gases in the minimum modes spin a small turbine, and this allows the engine to easily pick up speed and work with greater efficiency. As the speed increases, the valve opens, which in turn sets the large turbine in motion. But the pressure that it creates must be increased, which is what the small turbine does.
After reaching maximum speed, the large turbine produces enormous pressure, which turns the small supercharger into aerodynamic drag. At this very moment, the automation opens the bypass valve, and compressed air enters the engine, bypassing a small turbine in its path.
But all the complexity of this system is fully offset by the flexibility of the engine and its highest performance.
What are the advantages of using Twin-Turbo and are there any disadvantages
The undoubted advantage of the Twin Turbo system is high power with a relatively small displacement of the engine. This also includes the high torque and excellent dynamics of a car equipped with Twin-Turbo. The twin turbo engine is much more environmentally friendly, than conventional, since turbocharging allows fuel to burn much more efficiently in the cylinder system.
Among the disadvantages of biturbo can be identified the complexity of operating such a system. The power plant becomes more sensitive to quality of fuel and engine oil. Turbocharged engines need a special oil, because without it the service life of the oil filter is noticeably reduced. The high temperatures in which the turbines operate adversely affect the entire engine of the car.
The main disadvantage of the Twin-Turbo system is high fuel consumption. To create an air-fuel mixture in the cylinders, a large volume of air is required, which entails an increase in the fuel supply.
Turbines wear out pretty quickly if you immediately turn off the engine when you stop the car. To prolong the life of the Twin-Turbo, you should let the engine idle for some time, thus cooling the turbines, and only after that you can safely get the ignition key.
Remember! Twin-Turbo is a complex and very sensitive turbocharging system that needs careful handling and quality components. Compliance with these simple rules allows you to enjoy the speed and dynamics of the car to the maximum.
First of all, it should be immediately clarified that there is no difference between the terms biturbo and twinturbo. It's just that the designation of biturbo in the world is more common than twin-turbo due to the presence of the Maserati Biturbo model, known in the 80-90s, which became the pioneer in the use of the biturbo scheme on production cars. That, in fact, is the whole difference.
Schematic diagram of a Maserati biturbo engine
The meaning of the biturbo or twin-turbo scheme is that two turbochargers have less inertia and their turbines spin up faster, which leads to an increase in engine output. There are also serial biturbo schemes, where one turbine operates at low engine speeds, and the second one is connected later. The most striking examples of modern biturbo applications include Pagani Huayra, Koenigsegg Agera, McLaren MP4-12C.
Conventional turbocharged cars tend to be content with one turbocharger, while the biturbo circuit is a more complex mechanism, therefore it is used only on the most powerful versions of civilian models. In addition, recently the use of a cheaper twin-scroll scheme, even on powerful modifications, seems to be cost-effective. In turn, to improve the efficiency of diesel engines, it is often preferred to use a single turbocharger instead of a biturbo, but with a variable turbine geometry.
The most sophisticated technical schemes for increasing the output of supercharged engines include a layout with three turbochargers (BMW X5 M50d) or four (Bugatti Veyron), as well as a combined Twincharger scheme, where a mechanical supercharger works in tandem with a turbocharger (Volkswagen and Volvo concern models). Well, the most common way to increase the output of supercharged engines remains intercooler, which is used on almost all modern turbocharged engines.
Pioneers of serial application of biturbo (table)
| Brand | Year of issue | Engine capacity, l | Power, hp |
