2011 Chevrolet Cruze preview

2011 Chevrolet Cruze preview

General Motors is fearlessly downsizing its four-cylinder engines in the new 2011 Chevrolet Cruze, and looking, in most of the Cruze lineup, for turbocharging to bring small-four fuel economy without sacrificing peppiness and drivability. While a naturally aspirated, 1.8-liter four-cylinder engine will be standard on the base Cruze LS, the fuel-efficient star of the lineup—and the engine on offer in all the rest of the Cruze trims—is a new (to North America) 1.4-liter turbocharged four-cylinder engine that produces 138 horsepower.

GM says that the engine, which will also be installed sans turbo in the 2011 Chevrolet Volt, will offer best-in-segment fuel-efficiency (40 mpg highway in the Cruze Eco), and calls it "one of the most fuel efficient four-cylinder engines of its kind in the world"

But it's worth noting a few key design differences between the Cruze and the all-new 2012 Ford Focus that's waiting in the wings, for introduction just a few months after the Cruze.

For one, Ford is planning to offer a larger standard engine on the Focus—a 2.0-liter unit—featuring direct injection. That will be the only engine on offer at launch, but a version of the automaker's EcoBoost turbocharged four-cylinder engine—likely a 1.6-liter—is also expected to follow.

But is GM pitching the new 1.4T with a performance angle, as Ford will no doubt do for that EcoBoost option? It appears not. The assistant chief engineer for the Ecotec four, Mike Katerberg, explained that the 1.4T was tuned for everyday drivability more than power figures. "The turbo was sized really for two reasons; one is for maximum low-speed torque as opposed to top-end power," he said. "The intent was to make it look like a larger-displacement engine."

The engine produces its 148 lb-ft peak torque at just 1850 rpm, and as reported with a preview drive of the 2011 Chevrolet Cruze on companion site The Car Connection, the Ecotec 1.4T really does feel like a larger-displacement four—more like a 2.2-liter (the size installed in the Chevy Cobalt) in overall responsiveness.

As for why GM didn't opt to install direct injection in the U.S. version of the 1.4T, it was a conscious decision to hold down cost and complexity for the Cruze, a vehicle for which price will be very important. "In General Motors, we have a wide variety of fuel-saving technologies," elaborated Katerberg. "We do use direct injection on a number of other engines…but for what we were trying to accomplish with the Cruze, port fuel [injection] is the right choice."

GM's Mike Katerberg with 1.4T Ecotec

GM's Mike Katerberg with 1.4T Ecotec

In addition to direct injection, the Ford fours will all have aluminum alloy construction, which engineers have boasted for years cuts weight and aids warm-up for better fuel economy and emissions. On the other hand, GM uses a two-piece cast-iron block and structural aluminum oil pan, which it says helps air stiffness and curb noise and vibration, as does a dual-mass flywheel. The engine also incorporates a chain drive for easy maintenance, plus hollow camshafts to save mass and reduce rotational inertia, and a variable-displacement oil pump to reduce pumping loss when not as much flow is needed. It's all packaged neatly, with the turbo in the exhaust manifold, which aids emissions, coil-over-cylinder ignition, and roller finger followers with hydraulic lash adjusters to reduce friction. Additionally, the continuously variable cam phasing is a feature that was just introduced in this latest 'Gen 3' version this past year.

And, according to GM, the benefits of aluminum might not be as great with small cars anyway. In fact, there are packaging advantages in having an iron block. Using iron instead of aluminum, you can make a small-displacement four shorter by sticking with an iron block, according to Mike Katerberg, assistant chief engineer for the 1.4-liter turbo engine, and there's no concern for cylinder liners. "As well, you get the excellent characteristics of NVH out of iron."

And as for the thermal and weight advantages, Katerberg says: "We've done studies, that actually the smaller the engine, the closer iron and aluminum come together. We're utilizing thin wall technology, so really the mass is very equivalent to what an aluminum engine of the same displacement would be."