Chevrolet is introducing a new powertrain option for the 2014 Impala executive sedan that offers an almost perfect balance between refinement, economy, and performance. The new 2.5 liter Ecotec unit benefits from an advanced valvetrain technology and noise reduction system.
Before we get to those though, let’s see what ind of power it delivers, because what is the point of a refined, frugal engine if it doesn’t have decent performance. Fortunately, it’s not bad. The impala’s 2.5 liter four-banger makes 196 horsepower (146 kW) and 186 lb-ft of torque (252 Nm). Now that’s what a 2.0 liter European engine makes these days. what the extra half a liter is for we don’t know.
The motor’s new valve system is a beauty though. It uses an all-new rocker arm that switches between low and high lift intake cam profiles. The mechanism is actuated by an oil control valve through a dual-feed stationary hydraulic lash adjuster. Optimal lift profile is decided by the car’s computer based on conditions such as engine speed and load.
The benefits of this system, put simply, is that you get the perfect valve action depending on your style of driving. It engages in a low-lift mode when you are just cruising around and don’t need much power, and switches to high-lift mode at higher engine speeds or under heavy loads, providing the full output capability of the engine. In a normal engine you get the same lift profile all the time, which obviously is not optimal.
Variable valve lift system is nothing new. It’s been used by Japanese and European car makers for years. It’s a good thing that GM is finally adopting these technologies.