Check Drive: 3L Duramax diesel impresses in towing, off-roading in GMC’s 2020 1500 Sierra
When GM got down to design the 3.Zero-liter Duramax diesel, the automaker wished to create a no-compromise engine, says John Barta, assistant chief engineer and the staff lead on the brand new engine.
What Barta and staff have delivered is fairly shut. After a couple of hours driving each a GMC Sierra 1500 Denali and a Sierra 1500 AT4 geared up with the engine via the Rocky Mountains close to Jackson, Wyoming, this engine can be on the high of my listing relating to out there choices for GMC’s mild obligation pickup.
With the 3L Duramax, GM has delivered a low-noise, high-mpg engine that, whereas not essentially the most highly effective (relying on what you think about a real measurement of energy, extra on that in a bit), can pull quite a bit with a whole lot of confidence.
Growth and specs
Earlier than we get into the drive, let’s recap a bit. The brand new 3L Duramax is the primary inline-six turbo diesel GM has ever provided in half-ton truck. Gasoline financial system is an estimated 23 mpg metropolis, 30 mpg freeway, and 26 mpg mixed. The engine produces 277 horsepower and 460 lb-ft of torque. That peak horsepower, which doesn’t kick in till 3,750 rpm, is simply sufficient to offer GM the nod for many energy in a light-weight obligation diesel engine, edging out Ram’s 260 hp produced by the brand new and improved 3L EcoDiesel.
Nevertheless, the EcoDiesel delivers 480 lb-ft, sufficient for Ram to make declare to most torque within the section.
GM first introduced the 3L Duramax approach again in January 2018 and it was initially deliberate to be out there on 2019 mild obligation truck fashions. That by no means materialized attributable to what Barta stated have been early provider points that disrupted manufacturing of the engine. The provider points have been adopted intently by additional delays brought on by difficulties with clearing emissions exams.
The delays mounted up, Barta says, and somewhat than tack the engine on because the 2019 fashions have been being sunsetted, GM selected to easily formally introduce the engine for 2020.
Now that historical past is out of the best way, let’s discuss driving. My first expertise with this engine got here with a brief—and I do imply quick—off-road impediment loop in a 2020 Sierra 1500 AT4 geared up with the 3L Duramax.
The primary impediment within the course was a steep mound coated in massive rocks. On the best way up and down, I obtained an opportunity to check out the Hill Begin Help and Hill Descent Management options, respectively, included with the AT4 trim. Nearing the height of the rocky summit, I introduced the truck to a cease with the brake pedal and after a second let off. Hill Begin Help did it’s job, maintaining us from flying again down the 30-40-degree incline. After cresting, I moved ahead, dropping the nostril of the truck towards a tunnel of kinds dug out of the bottom and coated by a number of reduce and stripped bushes. I ended the truck and once more let off the brake. Once more, no motion because of Hill Descent Management. I gently pressed the accelerator to get the truck shifting once more and inside a second or two, the truck regained momentum and sank down into the tunnel.
It was a pleasant demo on a big rock characteristic, certain, however it’s additionally one thing that can put you a bit extra comfortable when towing as nicely. One other comforting characteristic is the view of the path in entrance of you from the sprint of the AT4 because of a digital camera mounted on the entrance finish of the truck. It makes maintaining your strains on the path a lot simpler.
So far as climbing the hill went, the truck dealt with it with little bother and with no touchiness within the accelerator. The AT4 has a Traction Choose System with a devoted off-road mode (Tour, Sport and Tow/Haul are the others.) A twist of the knob into off-road mode, and a button press to place the truck into 4LO and you may throw fairly a bit on the Sierra 1500 AT4 and it gained’t blink.
The AT4 additionally brings a 2-inch elevate equipment, Rancho shocks, an automated locking rear diff, 18-inch wheels (20 optionally available) and further skid plates. And whenever you add within the eye-opening pep off the road and the extra torque that the 3L Duramax brings to the desk, all of it quantities to a truck that may be very enjoyable to drive via mud and gravel.
After rising from the muddy impediment course, I hopped right into a barely cleaner AT4 Duramax and was in a position to run the truck via a fast observe reduce right into a grass discipline with some mild hills. As a result of dimension of this loop, I used to be by no means in a position to safely get the truck as much as greater than 40 mph, however I did discover the grip of the optionally available Goodyear Duratrac tires and the boldness within the truck’s stance whereas taking a couple of tight corners at velocity.
However the greatest takeaway from the fast journey was the pep on this 3L engine’s step. With this engine, the AT4 actually jumps off the road. And due to the 10-speed transmission, shifting between gears is almost indiscernible.
Backside line, if you happen to’re going to go together with the AT4 package deal and also you’re planning on truly taking that truck off-road, give the 3L Duramax choice some critical thought. The engine feels a lot at residence with that package deal that it could make sense if it was the default engine alternative for that trim.
My final run with the 3L Duramax was in a Sierra 1500 Denali pulling a field trailer loaded right down to round eight,000 kilos.
Whereas eight,000 kilos is likely to be a quantity the Sierra HD vehicles, the 6.6L Duramax and its mammoth 900 lb-ft of torque sneer at, that trailer represents almost 90 % of the Sierra 1500’s towing capability when geared up with the 3L diesel. And whenever you throw in mountainous terrain and a 6-percent grade, you need to find yourself with a fairly stable thought of simply what this engine can deal with relating to pulling stuff.
I used to be accompanied on the towing check by Barta, who stated his design staff labored onerous in the course of the engine’s four-year growth cycle to optimize the run from the air consumption all the best way into the engine cylinder. Barta says the cooling know-how on the 3L Duramax can drop engine temperatures by as a lot as 100 levels Celsius.
“It’s a really quick distance into our turbo, and the turbo can increase as much as 29 psi proper into the the consumption manifold. By advantage of the clear sheet design that we needed to work with, we’re in a position to get that quick column of air boosted a lot faster than an engine that has longer runners from the turbo into the consumption,” Barta says. He provides that the inline-six design helps in that regard as nicely as a result of the “additional separation of two banks in a V6 (make it) naturally tougher to get boosting as fast to the cylinder than you’d like.”
Even loaded down, the 3L Duramax offers a comparatively fast leap off the road because of the engine’s 460 lb-ft of torque. The massive good thing about towing with this engine although is the exhaust braking. In contrast to the exhaust braking discovered on GM’s heavy obligation vehicles, the implementation on the sunshine obligation Sierra is built-in with the truck’s tow/haul mode and can’t be switched on and off independently of that mode.
The truck pulled the trailer effortlessly. By the point we encountered that 6-percent grade, the truck had gained a head of steam and was cruising at round 50 mph. I leaned into the accelerator to push the truck to 55 mph and watched because the rpms climbed. We cruised with little effort all the best way up the hill. It wasn’t till round 3,500 rpm that the truck shifted gears, and by then we had reached the crest of the grade.
“Our torque band and horsepower give an excellent driving expertise as a result of we give torque all through nearly all the rpm band,” Barta says. “We hit our max peak torque at 1,500 rpms at 460 lb-ft. After which the torque curve is almost flat nearly to 3100 rpm after which drops off after which at 3,750 rpm we hit our peak horsepower.”
Our run up the steep grade with eight,000 kilos in tow bore out Barta’s declare. And it’s that torque band that Barta says units the 3L Duramax aside from the 3L EcoDiesel contained in the Ram 1500, regardless of that engine’s larger peak torque.
“Our opponents at Ram have accomplished an excellent job at getting 480 lb-ft of torque at 1,600 rpms however their torque curve drops off and rolls decrease than that because the rpms rise. Due to this fact, their peak horsepower isn’t as a lot and I feel that torque curves can predict very nicely how your driving expertise goes to be,” he says. “The realm below the torque curve and the horsepower can let you know how your driving expertise goes to be. And if you happen to evaluate these two, we have now a bonus over Ram for all the driving vary or rpm band.”
Actually, Barta says that the engine might be able to an excellent larger tow ranking. However on condition that 95 % of GMC’s mild obligation pickup clients don’t tow greater than 9,000 kilos, Barta says the tow ranking is excellent. He says these clients that need or must tow trailers north of 10,000 kilos are predominantly excited about a heavy obligation truck.
“It actually boils right down to a chassis. Whenever you get to towing [more than 9,000 pounds], you want weight in your chassis,” Barta says. “You want the energy out of your springs and all the things from the tires and the bearings. A lightweight obligation truck isn’t designed to tow a 15,000 kilos trailer. And so they shouldn’t be.”
Priced identically to the 6.2L V8 and $2,495 over the 5.3L V8, the 3L Duramax turbo diesel is a particularly enticing new choice for GMC consumers. There are three kinds of of us that I feel ought to give this engine robust consideration:
1. People who favor gas financial system.
2. These within the AT4 trim and wish an off-road succesful truck.
3. Those that shall be towing with any form of regularity.
Actually, if you happen to fall into two of these three classes, the 3L Duramax is a should. It provides a dimension of functionality, consolation and confidence to GMC’s mild obligation providing that beforehand wasn’t there.