"All new.” Two words that have been casually tossed about for so long their literal meaning has been lost to the winds of hyperbole. So yesterday, when General Motors announced its “all-new” Ecotec 2.5-liter 4-cylinder engine, I tempered the news with my usual dose of hard-earned cynicism. “Let me guess," I said to myself, "a slightly redesigned block and cylinder head yielding an additional tenth of a liter displacement is teamed with new fuel injectors to produce a 6 percent increase in output and improved overall drivability. Oh, and wait -- we mustn't forget the 'all-new' designs molded into the plastic engine cover.”
As usual, I skipped past the soft-sell portion of the press release and zeroed in on the technical details, where I found myself wholeheartedly intrigued by the impressive list of technical specs and comprehensive refinements on display in this fully modern 4-banger-to-be.
Scheduled to arrive midsummer 2013, the new Ecotec will debut as the base engine in the Chevrolet Malibu. Early projections peg horsepower at around 190 and torque at 180 lb-ft -- about 12 and 16 percent more, respectively, than the outgoing Ecotec 2.4. Mileage is said to be more than 30 mpg highway, although the Environmental Protection Agency has yet to confirm those numbers.
The new Ecotec is touted by GM as one of the quietest engines in this segment. The manufacturer made a concerted effort to redistribute the noise, vibration and harshness that it couldn't banish entirely.
“Think of it as the difference between low-frequency coarse noise, such as a vacuum cleaner, versus a higher frequency precision noise, such as a sewing machine,” says Tom Slopsema, noise and vibration engineer. “We focused on reducing the overall engine noise level and placing the remaining noise in a higher frequency range. Specifically, the engine’s noise-frequency signature was targeted, with the aim of pushing radiated noises into a higher frequency range well above 2,000 hertz, which is more pleasing to the ear.”
While these are all welcome improvements, it's the top-to-bottom, stem-to-stern attention to minutiae that impresses me most. Check out some of the improvements the engineers made, likely while the accountants were at lunch:
1. Relocated balance shafts: Moved from the block to a cassette in the oil pan, the balance shafts are driven by a shorter, quieter chain to reduce noise and vibration.
2. In-pan oil-pump assembly: The oil pump has been moved from the front of the crank to the oil pan, where it is driven off the aforementioned balance shafts.
3. Camshaft drive with inverted-tooth chain: The camshaft drive chain uses a premium, inverted-tooth design that is significantly quieter than a roller-type chain. Also known as a silent chain, it virtually eliminates noise and enhances durability.
4. 2-piece oil pan: The 2-piece oil pan employs a stiff aluminum upper section to support the engine’s structure, and a stamped steel lower section to provide greater overall sound reduction.
5. Structural camshaft cover: Featuring increased ribbing and additional attachment bolts, the cover's increased stiffness helps to push the engine’s sound frequency above 2,000 hertz.
6. Acoustic intake manifold cover: Hey, if you say it works, I'll take your word for it. Then again, all of my personal vehicles have nothing but air and grease between the top of the engine and the bottom of the hood. Of course they're older models as, apparently, am I. Funny I hadn't noticed that till now.
7. Forged steel crankshaft: This is big. Anyone who has ever built a performance engine knows a forged crank is the way to go for durability and reduced deflection under stress. These same properties also reduce noise and vibration, the two primary enemies of smoothness.
8. Iron main bearing cap inserts: These stiffen the structure at the main bearings where the crankshaft rests. Same story as above: Stiffer equals quieter and smoother.
9. Isolated fuel rail: The injectors are suspended and the fuel rail is attached with rubber-isolated mounts. Although not new to the 2.5-liter Ecotec, injector tick can be annoying, and is often mistaken for a sticky valve lifter.
10. Structural front cover: The 2.5-liter's front cover was designed with extra ribbing and secured with extra fasteners for a stiffer, more rigid and quieter cover.
Will the average consumer notice these refinements and feats of technical wizardry? I have no idea. Probably not. Am I absolutely geeked that a car company, formerly in the habit of leaving engine designs in their lineup virtually unchanged for decades, is getting all proactive about NVH and efficiency? You can bet your sweet bippy I am.
