Twin Turbo Is the commercial designation for an advanced turbocharging system.
The name Biturbo is also used, but you can also find an incorrect designation of this term for a parallel system with two turbines. This term is understood as a multi-link system for pumping air into the cylinders using two or more compressors driven by exhaust gases, which gives an increase in efficiency, power and reduces the toxicity of emissions.
Twin Turbo system
Twin Turbo was designed to solve the key problem of supercharged engines - eliminating turbo lag, which manifests itself as a decrease in elasticity and a sharp low revs engine, while the turbine has not yet had time to spin up under the pressure of the exhaust gases to the optimum speed. This is due to the fact that the impeller of the supercharger is made of special heat-resistant materials with a considerable margin of safety and therefore has a noticeable weight and moment of inertia.
Even high-tech lightweight ceramic rotors spin up to 200 thousand revolutions per minute in a quite noticeable time. Turbo lag, or turbo-lag, has an extremely negative effect on the dynamic characteristics of the engine, ultimately affecting the active safety driver and passengers.
As it turned out later, the dual one allows you to significantly expand the range of rated torque rpm, increase the maximum power and reduce the specific fuel consumption.
Like any system with more than one element, Twin Turbo can be parallel, sequential or staggered. Each of these schemes differs from the other in geometry, dynamic characteristics and the principle of work. The supercharging is controlled by the microcontroller unit, which receives information from the sensors and controls the valves and actuators on the intake and exhaust manifolds.
Principle of operation and features
Parallel system
A relatively simple system involving a symmetrical pair of compressors operating simultaneously to evenly distribute the incoming air. Most often, this scheme is used on V-shaped diesel engines where each compressor supplies air to the intake manifold of its cylinder group.
Reducing the inertia is achieved by reducing the mass of the turbine rotor, as you know, two small compressors provide slightly more pressure and spin up faster than one, but larger in size and performance. Thus, the width of the turbo lag is significantly reduced, and the engine provides several best performance throughout the entire rev range.
Sequential system
With this arrangement, two comparable compressors (not necessarily the same in characteristics) operate in a complementary mode.
Sequential Twin Turbo circuit:
1 - boost bypass valve; 2 - air supply control valve; 3 - pressure difference sensor; 4 - exhaust gas supply control valve; 5 - secondary turbocharger; 6 - intercooler; 7 - primary turbocharger; 8 - wastegate bypass valve.
One, usually lighter and faster, the supercharger works constantly, eliminating the deep and wide turbo lag, the second one, according to the signal from the electronics that monitors the engine speed, is switched on in heavier modes, ensuring maximum power and fuel efficiency. Such a series-parallel scheme (in peak modes, both turbines operate simultaneously) is used on engines of any fuel cycle.
In 2011, German BMW introduced the advanced Triple Turbo sequential charging system.
Step system
The most sophisticated and progressive system providing the widest power range.
Variable two-stage turbocharging scheme:
1 - charge air cooler; 2 - pressure bypass valve (bypass); 3 - turbocharger of the high-pressure stage; 4 - stage turbocharger low pressure; 5 - wastegate bypass valve.
To create such a boost, two different-sized compressors are installed, connected to each other by a system of pipes and bypass valves.
This type of turbocharging is called step-by-step due to the fact that, in minimum modes, the exhaust gases spin up a small turbine, and the engine spins up easily. As the speed rises, the valve opens and the large turbine begins to spin, but the pressure it creates needs to be increased, which is what the small turbine next to it does.
When reaching maximum speed, the large turbine produces so much high pressure that the small supercharger becomes drag. At this moment, the automation opens the bypass valve, and the compressed the air goes into the engine, bypassing the smaller of the turbines.
Rice - the operation of the variable two-stage turbocharging system
The complexity of such a system is more than compensated for by the flexibility of operation and the highest performance of the engine.
Modern Twin Turbo systems use other technical tricks to provide less inertia and more power. Electronic regulation of the volume of exhaust gases on the turbine wheel, variable geometry of the blades, a bleed valve, an unforgettable whistle of which indicates the safe removal of excess air in the intake manifold during gas discharge. The bypass valve is able not only to turn on and off a turbine that is not being used at a given moment, but also to maintain pressure when the throttle is briefly closed, returning the stock to the intake manifold instantly, during the valve closing time.
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A system as important as the Twin Turbo can be used in many ways. It can be one radiator with a common manifold, or separate coolers for each supercharger. A stepped system, for obvious reasons, always dispenses with one radiator.
The main problem with the use of turbocharging is the inertia of the system or the occurrence of the so-called "turbo lag" (the time lag between the increase in engine speed and the actual increase in power). To eliminate it, a circuit using two was developed, which was named TwinTurbo. This technology is also known by some manufacturers as BiTurbo, but the differences in designs lie only in the commercial name.
Features of Twin Turbo operation
Supercharging system TwinTurboSystems with two compressors are used on both diesel and gasoline engines... However, the latter requires the use of a higher quality fuel with a high octane number, which makes it possible to reduce the likelihood of detonation (a negative phenomenon that occurs in the engine cylinders, destroying the cylinder-piston group).
In addition to the main function of reducing turbo lag time, the Twin Turbo circuit allows for higher, lower fuel consumption and maintains maximum torque over a wide rpm range. This is achieved by using different schemes connection of compressors.
Types of supercharging schemes with two turbochargers
Depending on the method of connecting a pair of turbochargers, there are three main schemes of the TwinTurbo system:
- parallel;
- consistent;
- stepped.
Parallel turbine connection diagram
Provides for the connection of two identical turbochargers operating in parallel (at the same time). The essence of the design is that two smaller turbines have less inertia than one large one.
Before being fed into the cylinders, the air charged by both turbochargers enters one intake manifold, where it is mixed with fuel and distributed to the combustion chambers. This circuit is more commonly used on diesel engines.
Sequential inclusion
Daisy chain Twin Turbo The series-parallel scheme assumes the installation of two identical turbines. One works constantly, and the second is connected when the engine speed rises, the load increases or other special modes. Switching between operating modes is carried out using a valve driven by the vehicle's engine ECU.
This system is primarily focused on eliminating turbo lag and obtaining smoother vehicle acceleration dynamics. The systems with triple turbocharging TripleTurbo work in a similar way.
Step scheme
Biturbo step scheme Two-stage turbocharging consists of two turbochargers different sizes that are installed in series and connected to the inlet and outlet ports. The latter are equipped with bypass valves that regulate the flow of air and exhaust gases. The step circuit has three modes of operation:
- At low engine speeds, the valves are in the closed position. The exhaust gases pass through both turbines. Since the gas pressure is low, the impellers of a large turbine practically do not rotate. Air flows through both compressor stages, producing a minimum overpressure.
- As the engine speed increases, the exhaust valve starts to open, which drives the large turbine. The larger compressor compresses the air, after which it is directed to the smaller wheel, where additional compression is applied.
- When the engine is running at maximum RPM, both valves are fully open, which directs the exhaust gas flow directly to the large turbine, air passes through the larger compressor and is immediately sent to the engine cylinders.
The staggered scheme is most commonly used for diesel vehicles.
Advantages and disadvantages of dual turbocharging
Currently, TwinTurbo is mainly installed on high-performance cars. The use of this system allows to achieve such advantages as providing maximum torque over a wide range of engine speeds. Also, thanks to the dual turbocharging, an increase in power is achieved with a relatively small engine size, which makes it more economical than naturally aspirated engine.
The main disadvantages of BiTurbo include high cost, which is due to the complexity of the design. Just as with the classic turbine, systems with two turbochargers require more gentle treatment, better fuel and timely oil changes.
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 the 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 that uses only one turbine.
Biturbo was originally designed to solve the main problem all inflatable engines - elimination of the so-called "turbo lag". This phenomenon manifests itself 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 exhaust gas pressure does not have time to spin up to optimal speed.
Subsequently, it was observed that twin turbines allowed a significant increase in the range of rated torque rpm, thereby increasing maximum power, while simultaneously 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 systems: parallel, serial and stepped... Each type of turbocharging is characterized by its own geometry, operating principle and output 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, an even distribution of the incoming air is achieved.
This scheme is often used in diesel V-shaped engines, where each compressor is responsible for supplying air to the intake manifold of its cylinder group.
The reduction in 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 gives out the best performance in the entire rev range.
Consistent
This type implies a layout consisting of two commensurate compressors, which at the same time can have different characteristics and work in a complementary mode. The lighter and faster supercharger operates in a continuous mode, thereby eliminating deep and wide turbo lag. The second supercharger controls the engine speed using special signals from the electronics and switches on at heavier engine operating conditions, thus providing maximum power and fuel efficiency.
At peak engine operating conditions, 2 turbines are turned on at once, working in pairs. A similar scheme can be applied to engines with any fuel cycle.
Stepped
The most sophisticated and progressive type of turbocharger, providing the widest power range. The creation of the necessary boost is made possible by installing two different-sized compressors interconnected by a special system of bypass valves and branch pipes.
This type of turbocharging is called staged due to the fact that the exhaust gases spin up a small turbine in minimum modes, 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 drives a large turbine. But the pressure that it creates must be increased, which is what a small turbine does.
After reaching maximum rpm, the large turbine produces tremendous pressure, which converts the small supercharger into aerodynamic drag. At this very moment, the automation opens the bypass valve, and compressed air enters the engine, bypassing the small turbine on its way.
But all the complexity of this system is fully compensated 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 twin-turbo vehicle. The twin turbine engine is much more environmentally friendly than conventional, because turbocharging allows fuel to be burned much more efficiently in the cylinder system.
The disadvantages of biturbo can be distinguished the complexity of the operation of such a system. Power point becomes more sensitive to fuel quality and engine oil. Turbocharged engines need special oil, since without it, the service life is noticeably reduced oil filter... The high temperatures in which the turbines operate have a negative effect on the entire vehicle engine.
The main disadvantage of the Twin-Turbo system is high consumption fuel. To create a fuel-air mixture in the cylinders, a large volume of air is required, which entails an increase in fuel supply.
Turbines wear out pretty quickly if you turn off the engine immediately when you stop the car. To prolong the life of the Twin-Turbo, let the engine run for a while. idle, having cooled the turbines in this way, and only after that you can safely get the ignition key.
Remember! Twin-Turbo is a complex and highly sensitive turbocharging system that requires careful handling and quality components. Compliance with these simple rules allows you to maximize the speed and dynamics of the car.
Twin turbo and biturbo what is the difference and what are the differences
You've heard the names twinturbo and biturbo more than once, but what's the difference? And there is really no difference! Twin Turbo and Bi-Turbo are all marketing gimmicks and different names for the same turbo system. By the way, read useful article Neklyudin's bones about the pros and cons of various turbocharging systems
Contrary to the beliefs of some "experts", the name of the biturbo or twin-turbo system does not reflect the turbine operation scheme - parallel or sequential (sequential).
For example, in Mitsubishi car 3000 VR-4 turbocharging system is called TwinTurbo (twin turbo). The car has a V6 engine and has two turbines, each of which uses the energy of the exhaust gases from its three cylinders, but they are blown into one common intake manifold. For example, German cars have systems similar in operating principle, but they are called not twinturbo, but BiTurbo.
By car Toyota Supra with an in-line six, two turbines are installed, the turbocharging system is called TwinTurbo (twin-turbo), but they work in a special sequence, turning on and off using special waste valves. There are also two turbines on the Subaru B4 car, but they work sequentially: at low speeds a small turbine blows, and at high speeds, when it does not cope, a second turbine is connected bigger size.
Let's now analyze in order both systems bi-turbo (biturbo) and twin-turbo (twinturbo), or rather, what they write about them in "these your Internet":
Bi-turbo (biturbo) - a turbocharging system, which is two turbines connected in series. The biturbo system uses two turbines, one small and the other larger. The small turbine spins up faster, but at high engine speeds, the small turbine cannot cope with the compression of the air and the creation of the required pressure. Then a large turbine is connected, adding a powerful charge of compressed air. Consequently, latency (or turbo lag) is minimized, and an even acceleration dynamics is formed. Biturbo systems are not very cheap and are usually installed on high-end cars.
The bitrubo system can be installed like on a V6 engine, where each turbine will be installed on its side, but with a common intake. Either on an in-line engine, where the turbine is installed along the 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 aimed not at reducing turbo lag or leveling acceleration dynamics, but at increasing performance. In twin-turbo systems, two identical turbines are used, therefore 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 turbine, you can reduce the unwanted turbolag. But this does not mean that no one is using two large turbines. For example, in a serious dredge, two large turbines can be used for even greater performance. The twin-turbo system can work on both V-shaped engines and in-line engines. The sequence of turning on the turbines can vary, as with biturbo systems.
In general, for even more fun, no one bothers you to plug in 3 (!) Turbines or more at once. The goal is the same as for the twin-turbo. I must say that this is often used in drag racing and never on production cars.
By the way, read the useful article by Kostya Neklyudin about the pros and cons of various turbocharging systems
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On modern cars turbocharging is often used - 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 in other words. You can often find information about the fundamental differences between Twinturbo and Biturbo - in separate articles the definitions and essence of unique structural elements are given. Let's try to figure out 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 twin-compressor supercharging systems. Moreover, both Biturbo and Twinturbo involve the use of various variations of the technical part.
Various names have been coined by well-known marketers car manufacturers to differentiate our products from many similar machines built using the same layout. Interestingly, the Japanese prefer their twin turbochargers Twinturbo, while the European companies write Biturbo - this has happened historically. Cars from both parts of the world come to our country, so the name Biturbo and Twinturbo are familiar to the domestic consumer. Therefore, the dispute about the differences between the names of turbochargers can be considered untenable - but it will be interesting to learn about the 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 have to be installed on the same exhaust line, and a certain distance must be maintained between them. The problem is that the distant turbocharger will draw less power and operate less 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 the engine power using the Biturbo system.
The Biturbo system is used less and less
However, practice has shown that Twinturbo's sequential layout has several important disadvantages:
- The presence of a serious "turbo lag", that is, the speed range in which the turbines simply do not work;
- Sufficiently long response time to gas supply;
- Accelerated wear of the nearby turbine;
- Inconvenience of installation on V-shaped motors.
They tried to solve the problem different ways... However, the most elegant and efficient engineering solution proposed by Toyota, which made the inclusion of turbochargers of its Biturbo variant. At low revs, the valves are closed and the exhaust gases only pass through the small first turbine, easily spinning it up and providing an early exit from the "turbo lag". After reaching 3500 rpm, when the gas pressure is already becoming excessive, the electronics opens a special damper, and the hot flow rushes to the second larger turbocharger, providing a significant increase in engine power.
However, with the massive proliferation of V-shaped engines, the Biturbo sequential system became less and less used, 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, as well as increased engine power. In addition, the Biturbo parallel system, using compact turbines, eliminated the "turbo lag" and made the engine very sensitive to changes in fuel delivery.
In most cases, the parallel twin turbo scheme uses a common intake manifold, which makes it simpler and less expensive to maintain, but limits the vehicle's dynamic potential. Therefore, the Biturbo layout with separate intake tracts and manifolds was proposed as an alternative. 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 in series.
However, the most interesting Twinturbo scheme was proposed by BMW - its difference was in the location of the turbines in the V8 collapse, 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. This ingenious Biturbo system reduced the length of the turbo lag by 40% without compromising the reliability of the unit. In addition, the stability of the engine has significantly increased and the intensity of its vibrations has decreased.
Sometimes a Twinscroll turbine is confused with the Twinturbo layout. The latter assumes the use of one turbine with two channels and two sections of the impeller with different blade shapes. At low revs, a valve opens leading to a smaller impeller - as a result, the turbocharger accelerates quickly enough and provides a power increase without "turbo lag". However, as the crankshaft speed increases, the exhaust gas pressure becomes excessive and the second valve opens - now only the large impeller is used. As a result, the vehicle receives additional performance gains.
Of course, such a system is somewhat less efficient than the classic Biturbo. However, in comparison with one turbine, the thrust capabilities of the engine still increase. Of course, the Twinscroll layout is difficult to manufacture and considered quite unreliable. However, nowadays 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 from the crankshaft, while a turbocharger uses the energy of the exhaust gases and it is almost impossible to combine them. However, for Volkswagen engineers, nothing is impossible - they have included both nodes in their version of the Twinturbo system. The turbine runs continuously, while the compressor helps to eliminate the turbo lag at low rpm. Subsequently, it turns off, but when the accelerator pedal is pressed sharply, it re-enters into action, improving the engine's response to fuel supply.
The result of using this Biturbo option is a significant increase in power, reaching the torque limit at low rpm, accelerating the acceleration of revs, and also 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, on the cars of the brands belonging to the group of companies, it uses only one of the two pressurization options.
Summarizing the above, we can conclude that the differences between Twinturbo and Biturbo are only in the name. If you are really interested in various supercharging systems, you should pay attention to parallel and sequential layouts. In addition, it will 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 the 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 that uses only one turbine.
Biturbo was originally designed to solve the main problem of all inflatable engines - the elimination of the so-called "turbo lag". This phenomenon manifests itself 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 exhaust gas pressure does not have time to spin up to optimal speed.
Subsequently, it was observed that twin turbines allowed a significant increase in the range of rated torque rpm, thereby increasing maximum power, while simultaneously 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.
There are several basic types of Twin-Turbo systems: parallel, sequential and staggered. Each type of turbocharging is characterized by its own geometry, operating principle and output 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, an even distribution of the incoming air is achieved.
This scheme is often used in diesel V-shaped engines, where each compressor is responsible for supplying air to the intake manifold of its cylinder group.
The reduction in 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 gives out the best performance in the entire rev range.
This type implies an arrangement consisting of two comparable compressors, which, at the same time, can have different characteristics and operate in a complementary mode. The lighter and faster supercharger operates in a continuous mode, thereby eliminating deep and wide turbo lag. The second supercharger controls the engine speed using special signals from the electronics and switches on at heavier engine operating conditions, thus providing maximum power and fuel efficiency.
At peak engine operating conditions, 2 turbines are turned on at once, working in pairs. A similar scheme can be applied to engines with any fuel cycle.
The most sophisticated and progressive type of turbocharger, providing the widest power range. The creation of the necessary boost is made possible by the installation of two different-sized compressors, interconnected by a special system of bypass valves and branch pipes.
This type of turbocharging is called staged due to the fact that the exhaust gases spin up a small turbine in minimum modes, 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 drives a large turbine. But the pressure that it creates must be increased, which is what a small turbine does.
After reaching maximum rpm, the large turbine produces tremendous pressure, which converts the small supercharger into aerodynamic drag. At this very moment, the automation opens the bypass valve, and compressed air enters the engine, bypassing the small turbine on its way.
But all the complexity of this system is fully compensated 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 the high power with a relatively small engine displacement. This also includes the high torque and excellent dynamics of a twin-turbo vehicle. A twin turbine engine is much more environmentally friendly than a conventional engine, as turbocharging allows fuel to be burned much more efficiently in the cylinder system.
Of the disadvantages of biturbo, the complexity of the operation of such a system can be distinguished. The power plant becomes more sensitive to the quality of fuel and engine oil. Turbocharged engines require a special oil, as without it, the service life of the oil filter is significantly reduced. The high temperatures in which the turbines operate have a negative effect on the entire vehicle engine.
The main disadvantage of the Twin-Turbo system is its high fuel consumption. To create a fuel-air mixture in the cylinders, a large volume of air is required, which entails an increase in fuel supply.
Turbines wear out pretty quickly if you turn off the engine immediately when you stop the car. To extend the life of the Twin-Turbo, let the engine idle for some time, thus cooling the turbines, and only then can you safely take out the ignition key.
Remember! Twin-Turbo is a complex and highly sensitive turbocharging system that requires careful handling and quality components. Compliance with these simple rules allows you to maximize the speed and dynamics of the car.
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Bi-turbo and twin-turbo (twin-turbo), double supercharging - differences. Are they different or not?
Turbocharged engines are not as simple as they seem, there are many misunderstandings and uncertainties hovering 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's the truth? Indeed, what is the difference between these two structures of TURBO motors, 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 system "Bi-turbo" and "Twi-nturbo" are essentially one and the same. If you take English and look at the designation, Bi-Turbo and Twin-Turbo, you can see two prefixes "Bi" and "Twin" - roughly translated, it turns out - "TWO" or "TWO". Nothing else - as the designation of the presence of two turbines on the 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 bother? 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 the primary problem.
- Increased power.
- Engine structure.
I'll start with the simplest point - the structure of the engine. Of course, it's easy to fit a single turbine when you have a 4 or 6 cylinder inline engine. The muffler is one. But what if you have a V-shaped motor? And three - four cylinders on each side, then there are two mufflers! So they put on each of the turbines, medium or low power.
Eliminating turbo lag - as I wrote above, this is problem number "1". The thing is that the 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, this is not safe! So they install various turbines, and often a compressor + turbine. One works at low revs, that is, at the start to avoid "turbo lag", the second - at a speed when you need to leave traction.
The increase in power is the most commonplace case. That is, to increase the engine power, another powerful turbine is installed to the low-power turbine, thus they blow two, which significantly increases productivity. By the way, on some racing cars, there are three or even four turbines, but it is very difficult and usually does not go into series!
Here are the solutions for which "TWINTURBO" or "BITURBO" are used and you know this is a real 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. It is parallel and sequential (also known as sequential).
For example, some Mitsubishi have exactly "TWINTURBO", but the parallel operation, as I have already noted above, is two turbines on the V6 unit, one on each side. They blow into a common collector. But for example, on some AUDI, there is also a parallel operation on the V6 engine, but the name is "BITURBO".
On Toyota cars, in particular on "SUPRA", there is a straight-six, but there are also two boosts - they work in a tricky order, two can work at once, one can work, the other does not, can be switched on alternately. It all depends on your driving style - they achieve this work with "tricky" bypass valves. Here's a serial-parallel job.
As in some SUBARU cars - the first (small) injects air at low rpm, the second (large) is connected only when the rpm has increased significantly, so 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 these two structures, let's take a closer look.
As a rule, these are two turbines connected in series. In a striking example, 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 at the bottom, that is, the first. For low speeds and up to low revs, this is quite enough. But at high speeds and revs, this "baby" is practically useless, here you need a supply of a much larger volume of compressed air - a second, heavier and more powerful turbine is turned on. Which gives you the power and performance you need. What is the benefit of such a consistent placement in BI-TURBO? This is almost the exception of turbo lag (comfortable acceleration) and high performance at high speeds, when traction remains even at speeds over 200 km / h.
It should be noted that it can be installed both on a V6 unit (on each side with its own turbine), and on an in-line version (here they can divide the exhaust manifold, for example, one blows from two cylinders, and the other two from the other).
The disadvantages are the high cost and work on setting up such a system. After all, the fine settings of the bypass valves are used here. Therefore, the installation is due to 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, therefore another one of the same is installed (in parallel). Together they pump twice as much air for almost the same performance gain!
But what about the "turbo lag" that it is rampant here? But no, she is also effectively defeated only in a slightly different way. As I already said, small turbines spin up much faster, so just imagine - they change 1 big one, for 2 small ones - the performance practically does not decrease (they work in parallel), but the "PIT" leaves because the reaction is faster. Therefore, it turns out, create a normal traction, from the very bottom.
Installation can be both in-line models power units, and V-shaped.
Manufacturing and customization is much cheaper, which is why this structure is used by many manufacturers.
This can also be called "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 installed on a belt drive from crankshaft engine, therefore, it spins up as quickly as possible with it. Thus, allowing you to avoid the "PIT", but at high revs it is useless - here the turbo option already enters.
This symbiosis is used on some German cars, a big plus of the compressor, that it has a much higher resource than the opponent!
Now a small video, we are watching
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