What exactly is a twin-turbo engine? The Twin in TwinPower does not imply that the engine has two turbochargers. It actually refers to the exhaust manifold that separates the exhaust gases and allows them to pass through two scroll-shaped spirals.
What distinguishes TwinPower Turbo from TwinTurbo Power fundamentally?
Based on firing order, the exhaust manifold in both designs is evenly divided into two headers. The TwinPower Turbo, often known as the dual scroll turbo, is a single turbo powered by two exhaust down tubes and two pairs of alternating cylinders. Each of the two exhaust down tubes on the Twin Turbo Power’s two turbos is fed. Refer to the illustration below to see how the TwinPower Turbo technology looks. The following example is from a 4-cylinder engine, but the same concept may be used with 6-, 8-, and 12-cylinder engines.
Now that the fundamental concept has been clarified, we can further discuss why BMW shifted to the TwinPower design and its benefits over the Twin Turbo Power design.
Why Is This Important?
It is significant to remember that both single and double scroll turbochargers have the same cold side. The turbine, turbo shaft, and compressor are among the components that don’t change inside the turbocharger housing. The exhaust headers and the exhaust intake on the turbo housing are noticeably different. An exhaust manifold on a dual scroll turbocharger is divided into two headers according to the firing order.
The exhaust manifold and headers for a dual scroll turbo are shown on the left in the image above, and those for a single scroll turbo are shown on the right. Similar images for the turbocharger exhaust inlets can be found by performing a fast Google image search. Additionally, BMW TwinPower Turbo engines have two wastegates since the twin scroll turbo receives two distinct exhaust streams. Overall, there aren’t many differences. How can performance be improved by this small design difference?
A twin-scroll turbo is what?
Contrary to standard single-scroll turbos, twin-scroll turbos direct exhaust gases into two spiral cylinders (the scroll). These two cylinders have distinct shapes and diameters, yet they can both open and supply boost simultaneously. There are two: one bigger for peak performance and one smaller for quicker reaction.
The fact that a twin-scroll turbo employs both thermal and pulse waves produced by the exhaust is another benefit over a single-scroll turbo. On the other hand, a single-scroll just uses thermal energy. Twin-scroll turbos offer less turbo lag and perform better than single-scroll turbos overall since there are two sources of mechanical labor.
Moreover, twin-scroll turbochargers are a little more complicated. They have a more difficult manufacturing process and have more moving components, making them tougher to repair. Having said that, purchasing this kind of turbo also costs extra.
Compared to single-scroll turbochargers, twin-scroll turbochargers are superior in almost every manner. The exhaust pulses are split by two scrolls. For instance, cylinders 1 and 4 may feed to one turbo scroll while cylinders 2 and 3 may feed to a different scroll on a four-cylinder engine with the firing order 1-3-4-2. Why is this advantageous? As the piston reaches bottom dead center and the exhaust valve begins to open, let’s suppose that cylinder 1 is nearing the conclusion of its power stroke. However, there is some overlap as cylinder 2 completes the exhaust stroke, closes the exhaust valve, and opens the intake valve. Since both exhaust valves are briefly open in a conventional single-scroll turbo manifold, less pressure will reach the turbo and less air will be pulled in by cylinder 2, which will cause interference with the exhaust pressure from cylinder 1. In order to solve this issue, the scrolls are divided.
- The exhaust turbine receives more energy, which increases its power.
- Based on the various scroll designs, a larger RPM range of effective boost is feasible.
- There is additional tuning flexibility because higher valve overlap is allowed without impairing exhaust scavenging.
- need a certain engine configuration and exhaust design (eg: I4 and V8 where 2 cylinders can be fed to each scroll of the turbo, at even intervals).
- Compared to standard single turbos, cost and complexity.
What it does
Similar to a regular turbo, a twin-scroll turbo increases airflow into an engine to boost performance and economy.
A twin-scroll turbo, in contrast, divides this into two channels that send air onto various parts of the turbine blades. In a typical turbo, however, one channel feeds gas from the exhaust manifold into a turbine.
The bigger channel pushes air onto the turbine blades’ exterior, which accelerates the turbocharger’s spooling.
As a result of the narrower channel’s ability to direct air to the inner region of the turbine blades, the turbocharger responds more quickly, which is especially useful at low engine speeds.
For different applications, the channels can have different sizes, but the fundamental idea is the same.
This twin-scroll design improves top-end power while also increasing low-rev response. Power delivery is more responsive and linear, maximum output is obtained at lower revs, and it lasts longer.
The operation of the BMW twin-scroll turbo.
You’ll see that the BMW TwinTurbo Power option utilizes two turbochargers. The two turbochargers are often positioned one next to the other in twin turbo technology. By forcing more air into the combustion chamber, these parts combine to increase your engine’s power and fuel efficiency.
What does a twin-scroll turbo serve?
The benefits of the atwin-scroll turbocharger technology sound like a list of assurances from an 1890s tonic. Twin-scroll turbochargers claim to increase power throughout the powerband, boost response, low-end torque, engine pumping losses, reduce intake charge dilution during valve overlap, lower exhaust gas temperatures, and maximize turbine efficiency. A properly constructed twin-scroll turbocharger system, in contrast to those tonics that mostly included grain alcohol, can deliver on all of its promises.
A twin-scroll turbo has what purpose?
The benefits of the atwin-scroll turbocharger technology read like a promise sheet from an 1890s tonic for health. Twin-scroll turbochargers claim to boost turbine efficiency, increase power throughout the powerband, improve boost response, decrease engine pumping losses, boost fuel efficiency, reduce intake charge dilution during valve overlap, and lower exhaust gas temperatures. A well constructed twin-scroll turbocharger system can deliver on all of its promises, unlike those tonics that mostly included grain alcohol.
Which turbo is used by BMW?
Since 2011, BMW’s petrol and diesel engines have been actively using the twin-scroll-based BMW TwinPower Turbo technology.
Does “twin-turbo” refer to two turbos?
Sequential twin-turbo engines feature two turbochargers, but only use one of them—or, occasionally, both—for high speeds.
Are twin-scroll turbos quicker to spool?
Every turbo is matched based on three criteria: driving style, dependability / street-ability, and price. For 4, 6, and 8 cylinder engines, both gas and diesel, a very particular procedure is needed to match the appropriate turbo.
Although turbo technology is not new, turbos are still widely used. Variable vane or geometry turbos for gasoline engines are the newest technology. These turbos contain movable gas direction vanes that allow the turbo to be tuned for the flow of exhaust gases.
The A/R of the turbine housing changes as the vanes move, boosting top end power or spool. It resembles having all the various A/R turbine housings in a single unit. Unfortunately, there aren’t many of these turbos available, and the majority of them are Porsche OEM fitments. As a result, variable vane turbos are uncommon in aftermarket applications.
If you’ve been looking for a new turbocharged car, you may have noticed the term “Twin-scroll” in the brochure. Actually, this is not brand-new technology; rather, it is being reintroduced to the battlefield. In the 1980s and 1990s, twin-scroll turbos were installed on almost all rally cars.
The term “twin-scroll” describes the turbine housing’s style. The scroll, or portion of the turbine housing that resembles a snail shell, is separated into two distinct routes for the exhaust stream to follow.
A twinscroll turbo requires unique exhaust plumbing in order to function effectively, unlike a variable vane turbo. The two scrolls or routes are designed so that successive exhaust gas pulses follow contrasting paths. The first and third cylinders are therefore piped to one side, while the second and fourth cylinders are plumbed to the other, if an engine’s firing order is 1-2-3-4.
The pulses can’t interfere with one another since they are kept apart as they move through the turbo. We’ll compare it to a boxer working out on a speed bag. He can only strike the bag so quickly if we only give him one way (one hand). He can now hit the bag considerably more quickly if we allow him to use two paths (two hands). His hands follow completely different routes, so they can’t collide and slow things down.
While twinscroll technology can help most cars, there are several situations where it can result in considerable losses. A turbine housing with a low A/R will spool more quickly than one with a higher A/R, but the larger one will provide greater top-end power.
The majority of the turbos we use have an A/R between 0.55 and 0.85. These same turbos’ twinscroll variations frequently have A/R ratios of 1.02 or higher.
Long piping with a high A/R result in a very slowly spooling turbo on engines (such as Subaru’s) where there is a substantial distance between the exhaust ports and the turbo.
Consequently, there is simply too much exhaust piping on Subarus for the twin-scroll to be of any use. We advise sticking with conventional single scroll turbos for these engines.
Do twin turbos outperform single turbos?
Twin scroll kits are less common than single turbo kits. Why? They are smaller and more economical. If you already don’t have much space under the hood, the latter quality can be really helpful. Single turbos produce more horsepower and increase boost more slowly than twin turbo setups because they have a wider power band. Due to the extra traction, a single turbo is preferable when wanting to improve the performance of a muscle car.
Twin turbos would add how much horsepower?
Your engine’s output from a twin-turbo can increase by 100 to 250 horsepower. This is a fantastic technique to increase the power of your engine and help you reach some astounding speeds. Additionally, a twin-turbo can improve fuel efficiency and help you get the most out of your engine.
Just make sure to modify your engine in other ways to accommodate the extra power, or you risk damaging your vehicle the harder you push it.
Twin turbo or one turbo, which is faster?
At the same boost level, the smaller twins had less power (751 hp vs. 719 hp) than the large, single S475. The truth is that the difference can only be traced to these particular turbos, despite the fact that we may all be tempted to think that a single engine produces more power than twins.
Technical editor Richard Holdener has worked in the motor sector for more than 25 years. In addition to writing several articles for magazines like Hot Rod, Car Craft, Super Chevy, Power & Performance, GM High Tech, and others, he has produced several books on the subject of developing performance engines.
Is the 2.0 turbo engine in the BMW reliable?
The N20 engine is generally dependable, but the earlier models frequently have timing chain problems that can be expensive to correct. Not every engine will encounter problems permanently just because some engine faults are widespread. N20 engines are also prone to a wide range of other problems, which we won’t categorize as common problems because they might only occur on a small number of engines. What then are the BMW N20’s most frequent problems?