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GM's New 2.5L Four-Cylinder Engine Will Be Standard in Malibu

September 19, 2011

General Motors said it expects the 2.5L to deliver an estimated 190 horsepower (140 kW) and 180 lb.-ft. of torque (250 Nm).
General Motors said it expects the 2.5L to deliver an estimated 190 horsepower (140 kW) and 180 lb.-ft. of torque (250 Nm).

MILFORD, MI - General Motors' Chevrolet division revealed the details of its all-new Ecotec 2.5L four-cylinder engine. The new power plant will be standard in the 2013-MY Malibu. The new engine will be available in the summer of 2012.

General Motors said it expects the 2.5L to deliver an estimated 190 horsepower (140 kW) and 180 lb.-ft. of torque (250 Nm). These performance figures reflect about a 12-percent horsepower improvement and a 16-percent boost in torque when compared with the current Ecotec 2.4L. GM also said it expects highway fuel economy to exceed 30 MPG, though final fuel-economy figures are still pending.

“The noise intensity is 40 percent less than our 2.4L direct-injected engine, which was named one of Ward’s 10 Best Engines,” said Mike Anderson, global chief engineer. “Engineers also tuned the 2.5L to deliver more of its torque at lower rpm, giving the Malibu a stronger feel at launch and during on-demand maneuvers, such as passing or accelerating on a freeway entrance ramp.”

GM said increasing engine efficiency was the top priority for the company’s engineers. The automaker said it achieved efficiency improvements by working to reduce engine friction via a range of technologies. Engineers were able to reduce friction by 16 percent across the entire speed range, using technologies such as a variable-displacement oil pump and an actively controlled thermostat. The automaker also used its proprietary computational fluid dynamics (CFD) analysis techniques to develop a new combustion system with a higher compression ratio.

The new system features better knock resistance and higher flowing intake and exhaust ports in the cylinder head. These two improvements boost efficiency, power, and torque, according to GM. The engine also features increased-authority cam phasing (i.e. a greater ability to position the camshaft with precision using the cam phaser) which helps minimize the trade-offs between efficiency, performance, emissions, and driveability).

The engine uses some technologies in the current generation of Ecotec engines. The new 2.5L engine features a high-pressure, direct-injection fuel system, dual overhead camshafts with continuously variable valve timing, electronic throttle control, and pistons with jet-spray oil cooling.

Here are some of the engine’s other features:

  • Balance shafts relocated from the block to a module with an integrated oil pump in the oil pan to reduce noise and vibration
  • A stiffer and stronger forged steel crankshaft that enables quieter and smoother engine operation at high rpm
  • Inverted-tooth chains for the camshaft and balance shaft drives for quieter operation  
  • A unique, two-piece oil pan design, with an aluminum upper section to provide structural support and a stamped steel lower section to dampen overall noise
  • A cast aluminum bedplate with cast iron bearing cap inserts to help increase dynamic stiffness and reduce noise and vibration
  • Key sound attenuation enhancements such as a structural front engine cover, structural cam cover, and lightweight composite acoustic intake manifold cover.

The new Malibu will be sold in nearly 100 countries on six continents. It is available in LS, LT, ECO, and LTZ models in North America. Malibu will be built in multiple locations around the globe, including the Fairfax, Kan., and Detroit-Hamtramck assembly plants in the United States, according to GM.

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