|2014 ECOTEC 2.5L I-4 iVLC DI (LKW) with stop/start. Click to enlarge.|
Ninety-seven percent of customers in the US who purchased a 2014 or 2015 Malibu—accounting for about 83,000 vehicles—opted for the 2.5-liter, 4-cylinder base engine (LKW) equipped with standard stop/start technology, according to GM. (Earlier post.) This marks the the most aggressive rollout of stop/start technology in the US by an American automaker.
The 2014 Malibu was the first in its segment with a standard engine featuring fuel-saving stop/start technology. Stop/start is featured along other technologies in the Malibu’s new 2.5L intake valve lift control (iVLC), powertrain along with direct injection, variable valve lift control and a new six-speed automatic transmission. All contribute to EPA-estimated fuel economy ratings of 25 mpg (9.4 l/100 km) in city driving and 36 mpg (6.5 l/100 km) on the highway—14% and 6% improvements, respectively, over earlier models.
The LKW 2.5L features a unique two-step intake valve actuation system designed to enhance efficiency and help lower emissions, while also enhancing low-rpm torque, for a greater feeling of power at lower speeds. When the 2.5L’s iVLC system operates in low-lift mode, the engine pumps only the air it needs to meet the driver’s demand. The system switches to high-lift mode at higher speeds or under heavy loads, providing the full output capability of the engine.
The start/stop technology shuts down the 2.5L engine to save fuel when the vehicle stops momentarily, such as stoplights, to save fuel and reduce emissions. The engine automatically starts within 337 milliseconds when the driver takes his or her foot off the brake.
An auxiliary battery powers electric accessories such as the climate system, power windows and radio during engine restarts.
In April, GM received an Innovation Partnership Award along with BorgWarner for collaboration in a newly developed solenoid valve that is part of the stop/start system applied in MY2015 vehicles, the Impala and the Malibu. (Earlier post.) Additionally, BorgWarner received a PACE award for the specific work the supplier accomplished on the solenoid valve.
The stop/start system in the Impala improves city fuel economy by 5%, or one mpg for an EPA-estimated 22 miles per gallon (10.7 l/100 km). The 2015 Impala is available for sale now.
The solenoid valve is a low-noise, high-flow, low-leak valve that achieves quick hydraulic pressure for smooth launches when the engine restarts. The technology helps deliver improved fuel economy and performance as part of a stop/start system.
Stop/start technology capitalizes on vehicle idling occurrences. According to Sustainable America, the average American driver spends 16 minutes each day idling in his or her vehicle. That adds up to four days a year going nowhere.
A 2013 report from Navigant Research predicted worldwide sales of vehicles with stop/start technology will grow from 8.8 million in 2013 to 55.4 million in 2022. (Earlier post.)
J.D. Power’s most recent Initial Quality Survey, which measures the quality of vehicles after 90 days of ownership, showed customers ranked the 2014 Malibu higher than any other vehicle in its segment.
The 2.5L has refined many components to provide a quiet, efficient engine. The engine’s noise frequency signature pushes radiated noises into a higher frequency range to maintain low noise levels. Other highlights include balance shafts to reduce noise through a shorter, quieter drive chain, as well as precision shaft-to-shaft reversing gears and light drag torque from driving the oil pump.
The oil pump is located within the oil pan where it is driven by the second balance shift, reducing noise and providing a small drag torque for quiet balance shaft gear operation The camshaft drive uses an inverted-tooth chain to reduce noise and enhance durability.
A unique, two-piece oil pan made of aluminum and stamped steel offers a stiff structure and noise reduction. Structural camshaft and front covers improve stiffness for less noise and excellent oil sealing An acoustic intake manifold cover, a forged steel crankshaft, an isolated fuel rail and iron main bear cap inserts all help reduce noise.