Four-cylinder turbocharged engines will business relationship as an important piece in the overall hereafter strategy for BMW. The importance of the new N20 four-cylinder turbocharged engine was revealed at the 2011 Geneva Motor Show when Dr. Klaus Draeger, R&D chief, opened the BMW press conference with a speech on the new 4-cylinder engine.

In the future, BMW will make extensive utilise of the different iv-cylinder turbo engines in various models, from the 1 Series to the 3 Series, and some Ten-models. The first step in their EfficientDynamics strategy around four-cylinder bangers starts with the BMW X1 xDrive28i, the first model to receive the recently unveiled N20B20 4-cylinder engine that delivers 245 horsepower, offer similar performance as the six-cylinder aspirated engine only with significantly lower fuel consumption.

To learn more virtually the engine, we sat down with Dr. Bernardo Lopez-Alvaredo, Caput of Drivetrain Evaluation.

Bernardo Lopez Alvaredo 655x616 BMWBLOG: Why the shift from six-cylinder naturally aspirated engine to a new iv-cylinder turbo?

Dr. Lopez: We come across ourselves every bit office of the overall EfficientDynamics strategy and engine evolution is 1 portion that contributes to information technology. In the last years, the six-cylinder turbocharged won several awards and the new four-cylinder engine is the lilliputian brother of this powerplant. In a way this is the extension of this technology that was offset proven in the N55 half dozen-cylinder twin-scroll turbocharger.

BMWBLOG: Why the modify from N54 twin-turbo to N55 twin-scroll which is the base of operations for the new N20 four-cylinder?

Dr. Lopez: The system here is in a way more efficient, because you have basically the aforementioned functions, you separate the exhaust from two pair of cylinders and introduce into the turbocharged system. Of course, we reduced the volume you lot demand, then it has a lot of advantages, less weight, less parts.

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BMWBLOG: What is biggest challenge in designing this engine?

Dr. Lopez: Our aim is to satisfy client that accept been used to the half dozen-cylinder engine, so for usa the big goal in engineering was to deliver fifty-fifty ameliorate operation with lower fuel consumption, while delivering the same level of quality. The technology components are already known from the six-cylinder, so some were modified for the four-cylinder. The decoupling of vibrations was a new office that we had to blueprint for the four-cylinder.

BMWBLOG: Is this the first use of Valvetronic, Vanos, and straight injection in a BMW 4 cylinder?

Dr. Lopez: The Valvetronic was first introduced in 2011 in a four cylinder engine. The Valvetronic has ii functions here: one, to lower the fuel consumption, a function nosotros already had in the four-cylinder naturally aspirated engine. Typically yous work against the throttle, and so y'all lose efficiency there. Basically what you do is completely open the throttle, but then you demand a manner to regulate the corporeality of air that goes into cylinder, and then we introduce the Valvetronic then the valves detect the peak. when they open up fully you get the total mode, when they open a tiny fleck, y'all're in idling speed. The cylinders don't works against the pressure level departure that is build up by the throttle. It'southward an efficiency measure that we had starting in 2001 and developed the system further over the years, and now in the turbo system what information technology is interesting is that it non only delivers an efficiency component, but a performance component also. If y'all use a turbo engine in a system without Valvetronic you have to wait until the amount of air has gone from the throttle to the intake of the engine. With the Valvetronic you can regulate it very shut to the engine, so y'all have a improve response.

BMWBLOG: Compared to the half-dozen-cylinder engine, is there a difference in turbo lag?

Dr. Lopez: The goals we received equally the powertrain unit was that this engine should have no turbo lag at all and I believe we have done a pretty adept job with that ask. From our signal view, you exercise not notice any lag due to some of the things I previously outlined.

BMWBLOG: Would yous say that the twin-scroll has a longer lifespan than the twin-turbo? We accept seen many issues in the by with the N54 powerplant.

Dr. Lopez: We did expect at the whole package. If we have two independent turbo systems, of course y'all potentially accept more problems, then you besides demand more space in the machine, more parts and in the end it would accept lower efficiency. If you make it possible to penalize the whole frazzle energy without whatever loses to the turbocharger, you get better efficiency. From an applied science point of view, if you tin do it with a single turbocharge, it's better, however you have to take into account that the cylinders interact with each other, therefore twin-curl. In a mode, this is the perfect solution.

BMWBLOG: Has BMW tried to tune upwardly this engine to see its full potential?

Dr. Lopez: The specific ability of this engine is 90kW per liter which is already quite high. When nosotros are looking at the overall properties, lifetime for example, when you raise it likewise high upwardly you might get problems with the response or at least yous have to practice about the intake system. Of course, turbo systems can always be charged with more but and so you have certain risks of the turbo lag which you have to compensate with boosted measures that likewise add together other "costs".

Some questions were further asked by our sister-mag BimmerToday.de

BimmerToday: Was there a item attention paid to the engine sound?

Dr. Lopez: Yes. It is of course true that iv-cylinder engines have a unlike sound, and yous have to take special measures hither. We have a different arrangement of the residual shafts, which leads to less vibration. Then we have the dual mass flywheel and a centrifugal pendulum installed, so vibrations from the engine can be "erased". In sum, we go over the whole speed range with an audio-visual vibration beliefs similar to that of the six-cylinder, in some places even superior to.