Used to be that turbos were used in performance cars, from the Saab Turbos of the late Seventies to BMW's current range of twin-turbo sixes.
These days, the little air pumps more often make smaller engines perform like bigger ones to give fuel economy. In brief, a turbocharger uses exhaust gases to drive a turbine that pumps more air into the intake manifold, so more gasoline can be burnt for greater power.
We write about this engine downsizing theme a lot, and we're hitting it again because our colleague Bengt Halvorson just looked at the 1.4-liter turbocharged four that GM fits to the upcoming 2011 Chevrolet Cruze compact sedan.
GM 1.4-liter turbo Ecotec - Chevy Cruze and Volt
2011 Chevrolet Cruze
2011 Ford Edge
Ford Four-Cylinder EcoBoost Engine
The plan for a four-cylinder EcoBoost engine has been known for some time, but these are the first specifics from Ford
From 2.2 to 1.4 liters
That turbocharged 1.4-liter Ecotec engine replaces the much larger 2.2-liter four in the Cruze's predecessor, the 2010 Chevrolet Cobalt. It puts out 138 horsepower, and its peak torque of 148 lb-ft peak torque comes at just 1850 rpm--meaning it's tuned for drivability rather than sheer performance.
That sounds a lot like Ford's line of EcoBoost engines, including a 3.5-liter V-6 that generates the 355 hp of a larger 4.6-liter V-8, and a 230-hp 2.0-liter four-cylinder EcoBoost engine that replaces a 3.0-liter V-6 in the 2011 Ford Edge.
No GDI for GM
In both EcoBoost examples, the engines are not only turbocharged but also use gasoline direct injection (GDI) for greater power.
But GM chose not to use direct injection on the Cruze's small turbo four. Mike Katerberg, assistant chief engineer for the Ecotec four, says it was conscious decision to hold down cost and complexity in a price-sensitive segment.
We were first
Katerberg also defended GM's use of an iron block rather than the lighter aluminum alloy construction that Ford employs. The smaller the engine, he says, the lower the weight savings, and iron offers both a slightly smaller block size and better noise suppression.
General Motors execs point out that GM actually used GDI before Ford did, in the 2007 Pontiac Solstice and Saturn Sky sports cars. And it continues to use GDI on other engines, Katerberg noted.
But GM doesn't particularly playing up the "Turbocharged!" angle of its new economy engine. It's simply labeled a "1.4T," with the letter suffix being the sole indicator that it's boosted.
Ford, on the other hand, has a consistent campaign built around its EcoBoost option. Just this month, it announced an accelerated schedule for rolling out more EcoBoost options, plus three new vehicles that will get EcoBoost engines by the end of this year.
Now trade journal Automotive News quotes GM's executive director of global advanced engineering, Uwe Grebe, as saying GM made a mistake by not labeling its downsized turbo engines--as Ford did.
Grebe told reporter Chrissie Thompson that General Motors is considering efforts that would let them catch up with Ford's EcoBoost marketing, although he declined to discuss the timing of any such effort.
Given GM's need to increase sales, a green label certainly couldn't hurt. We'll keep you posted when the company figures out how it wants to brand its fuel-efficient engines.