[YesAuto Engine Technology] Three years ago, Carlos Ghosn, the “family head” of the Nissan Renault Alliance, and Mercedes-Benz Group President Zetsche sat at a desk. In less than a minute, they signed each other An agreement. From this day on, the cooperation between Nissan Renault and Mercedes-Benz has deepened, and from this day, Nissan’s engine includes Mercedes-Benz engine DNA. Since then, we have seen German-flavored 4-cylinder turbocharged engines on the Infiniti Q50 (hereinafter referred to as Q50) and Q60, and the cooperation does not stop there. Time flies. At the just-opening North American Auto Show, Nissan exhibited a new 3.0T V6 engine. Is it still the product of the cooperation between the two?
This time Nissan has brought the 2016 Q50 and the new Q60 model. The new 3.0L twin-turbocharged V6 engine is in its configuration list. The powertrain is temporarily only available for American consumers to choose. . Whether it will be introduced to my country in the future is still unknown.
This brand new 3.0L twin-turbocharged V6 engine is named VR30DETT in the internal engine number of Nissan. From the naming rules of Nissan's engine in recent years, it can be guessed that it is equipped with turbocharging and direct injection technology.
According to the information published on the spot, this engine is divided into high and low power versions. Previously, Francois Goupil de Bouille, vice president of Infiniti in charge of the European market, confirmed to the media in an interview that it will not be mass-produced. It will be equipped with the Q50 Eau Rouge concept car with a 3.8T engine and powerful performance like the GT-R. The new 3.0T engine The launch of the car seems to be able to comfort the disappointed hearts of car fans.
From the parameter point of view, the VR30DETT engine has no advantage in the maximum torque value compared with the Mercedes-Benz 3.0T V6 engine code-named M276. However, the advantage of the Nissan VR30DETT engine is that the torque platform is wider and the power output is higher, which is not the same as the cylinder diameter. The same design as the itinerary is not unrelated.
In the intake and exhaust section, it uses a dual variable valve timing system. Interestingly, the timing adjustment system on the intake side uses an electromagnetic mechanism, and the exhaust side uses a traditional hydraulic adjustment mechanism. In contrast, electromagnetic adjustment is faster and more precise. In the cold stage, the electromagnetic system is connected earlier, which is also helpful for fuel-saving performance.
With the increasingly stringent emission regulations, especially the gradual increase in the requirements for the control of emissions during cold start of vehicles, more and more manufacturers have begun to use the design of exhaust manifolds integrated in the cylinder head. In this way, during a cold start, the shortened exhaust manifold is beneficial to reduce exhaust temperature loss, so that the three-way catalytic converter can reach the most suitable operating temperature faster.
For turbocharged engines, the response speed of the turbo will become one of the important factors that affect the driving texture. Therefore, manufacturers have cooperated with suppliers to equip their products with turbochargers with increasingly smaller inertia. In addition, the use of electronically controlled pressure relief valves with more precise control is also one of the optimization methods.
On the turbocharger, there is an inconspicuous detail that is easily overlooked. This is that its high-power version of the engine uses an optical turbine speed sensor. In other words, besides the computer can obtain the intake status information through the traditional sensor, the addition of the optical turbine speed sensor can also help the computer to obtain more accurate turbocharger blade speed information. More comprehensive information helps the computer to calculate more accurate intake efficiency information, which is convenient for its analysis and control of turbochargers and pressure relief valves, thereby improving its response speed and increasing engine power output.
It’s not enough just to spin fast, the optimization of the cooling system is also crucial. Therefore, on the high-power version of the engine, it is equipped with two water-cooled intercoolers.
The fuel injection method of this engine adopts the mainstream direct injection in the cylinder. In addition, it has the ability of stratified combustion. During the intake stroke, the fuel injector sprays fuel for the first time, which is formed in the cylinder with the help of the intake vortex. Uniform lean mixture; during the compression stroke, the fuel injection nozzle at the end of the compression stroke injects fuel for the second time. At this time, the concentration of the mixture around the spark plug is large and easy to ignite, thus bringing the lean mixture in the gas cylinder, which is beneficial Improve the economy of the engine.
When the engine is cold-started, the engine has not yet reached its normal operating temperature. Even if the first fuel injection is used, the fuel atomization effect will be very poor, so the fuel injector only injects fuel at the end of the compression stroke.
to sum up:
The reason for not using the Mercedes-Benz engine may not only be attributed to the commercial level. According to the current performance parameters announced by Nissan, the maximum power of Nissan’s new 3.0T V6 turbocharged engine code-named VR30DETT has surpassed that of the Mercedes-Benz E-Class and S Mercedes-Benz engines with the same displacement on models such as the GLE-Class, GLE-Class, GL-Class, etc., so obviously the performance of their own machines is stronger, why not?