Justin Pritchard
During high school in the late ’90s, my friend Nick had a 1987 Chevy Sprint. It was old and circling ever nearer to a one-way trip to the crusher, and it was the slowest, noisiest, and nastiest car in the student parking lot for some months.
Every day at lunch, five of us would pile into this poor little thing. Then, one afternoon during a celebratory end-of-week burnout, the Sprint’s engine finally exploded, gushing fluids and hissing loudly to its smoky, gurgling death.
Today, this may explain why many folks in my circle are a bit unsure about them to this day. But recently, I put about 3,000 kilometers on GM’s latest three-cylinder powertrain during consecutive test-drives of the Buick Encore GX and Chevrolet Trailblazer RS.
Both these compact crossovers share a powertrain that consists of all-wheel drive, a nine-speed automatic transmission, and an optional 1.3L turbocharged three-cylinder engine under the hood. Jamie Dewhurst is the national marketing manager for Chevrolet cars and crossovers, and I asked him to explain what goes into a modern three-cylinder engine. He explained, “With 115 horsepower per litre, the 1.3L is about 15 per cent more power-dense than the 1.4L in the Trax, and is more power-dense than the outgoing LT4, which powered the 2019 Corvette Z06. There are also emissions benefits. The 1.3L produces eight per cent fewer CO2 (emissions) per kilometre than the Trax’s 1.4L (four-cylinder).”
I found the new engine and powertrain team to be a pleasant surprise, and one of the most valuable assets shared by both machines. With output rated at 155 horsepower and 174 pounds of torque, the optional 1.3L turbo engine hits harder than its tiny size suggests. Notice the torque output figure leading the horsepower figure by a fair margin? That’s characteristic of turbocharged engines, and is a signal to shoppers that they’ll benefit from strong pulling power at lower revs.
“The 1.3L turbo features a comparatively long stroke, 91.2 mm, compared to 79 mm bore dimensions,” Dewhurst said. “This bore-to-stroke ratio improves combustion and promotes excellent low-rpm torque production. It’s compounded with a low-inertia turbocharger, enabling the peak torque of 174 to be achieved at only 1,600 rpm, and sustained until 4,000 rpm. This is a distinguishing factor and something that the driver benefits from, because it is usable torque in the normal driving range. Add to this the fact that the 1.3L is over 20 pounds lighter and has more horsepower and torque than the 1.4L (and that) is the cherry on top.”
The new 1.3L turbo engine features a quick-to-respond Auto-Stop feature that reduces emissions during idling, as well as dual camshafts acting on 12 valves, with fuel supplied via direct injection. With that strong, low-end torque, a light-footed driver will experience smooth and pleasing forward thrust with a minimal squeeze on the pedal. Other than the odd grumble from the engine at very low speeds, drivers will hear and feel fairly little from under the hood when they’re in no particular rush, while still getting that pleasing throttle response. The gist? It’s a little engine that’s small but robust, and drivers can expect plenty of power for the daily grind. Interestingly, the engine’s generous low-rev torque enables two specific benefits that help further refine the entire driveline, too.
First, with more torque available at low engine speeds, the engine operates more quietly most of the time, since it doesn’t need to spin too quickly to provide ample get-up-and-go. From the driver’s seat, that means more acceleration with less noise. Second, generous low-end torque means the transmission spends less time shifting as you tackle hilly terrain, or in stop-and-go highway traffic. Fewer shifts means a smoother and more refined driveline.
Add it all up, and you’ve got an engine that never sounds or feels too busy. Even at full throttle, I found the engine noise to be tastefully restrained and pleasing enough to the ears that I didn’t mind the sound that does make it through the firewall. I’m not sure Lexus or Mercedes currently make a four-cylinder engine as quiet when worked as GM’s new turbo-three.
“Floating piston pins reduce stress on the pin, allowing for tighter tolerances and reduced noise, engine wear and improved durability,” said Dewhurst, who went on to describe a long list of engineering and design touches deployed within the engine to help bolster smoothness and efficiency. By carefully manipulating turbocharger control, targeting thermal management, and using a dual, independent cam-timing system, the engineers created the new 1.3L three-cylinder engine with refinement as a priority.
Extensive calibration and integration efforts between the engine and its transmission were carried out to make sure this powertrain team plays very nicely together. From the driver’s seat, that transmission smooths things out by shifting nearly invisibly at lower revs, and with precise full-throttle upshifts executed with a little breath between each gear, to help smooth things out even more.
While it isn’t fast, the turbocharging is excellent. Power arrives at low revs, and there’s consistent pull available across the rev range. This means the engine doesn’t feel like it’s running out of steam as redline approaches, and it never sounded or felt like it was struggling. It’s got smoother and quieter pulling power than I was expecting, and feels, sounds, and just acts like a high-end product no matter how you’re driving it. Go light on the throttle, and there’s plenty of response with minimal revs and noise, perfect for oozing up to speed peacefully. Operated more spiritedly, the torque gives a satisfying shove into your seat, and the clean shifting and tastefully-restrained growl from the three little cylinders is refined and well behaved.
On a final note, the AWD system can be toggled on and off with a switch. It’s an extra degree of control over the driveline that most crossovers don’t offer.
GM’s latest little powerplant is a nicely-executed piece of hardware that adds polish and spirit to the driving experience. And you’ll be seeing more engines like this soon.
Copyright Postmedia Network Inc., 2020
