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'Killing a Duramax' Gale Banks YouTube series methodically tunes a diesel to death

Learning or perfecting a skill by watching YouTube videos is known as attending YouTube University. GM Authority picked up on one of the video site's more fascinating courses, hosted by Gale Banks; in a fair world, he should be referred to as Professor Banks when it comes to diesel engines and truck tuning. A few months after GM introduced the updated L5P 6.6-liter Duramax diesel V8 in the 2020 Chevrolet Silverado HD and GMC Sierra HD that ships with 454 horsepower and 910 pound-feet of torque, Banks decided he wanted to methodically tune the engine to death. The purpose of the resulting series, called "Killing a Duramax," is to push more power out of the engine in order to discover which parts break and when — or, as Banks puts it, force-feed the Duramax "until the crank hits the street and the heads hit the hood." With that knowledge, Banks can figure out all the weak points on his way to building what he calls a "Superturbo," that being a supercharged, twin-turbo race engine with more than 1,000 hp. What makes the series fascinating is Banks' knowledge, paired with the company's comprehensive iDash engine monitoring system that keeps tabs on a glut of parameters every step of the way. So for instance, you get Banks explaining the differences between inches of mercury and barometric pressure, how those are different from the water content of the air measured in grains, then showing those readouts on the iDash, then explaining in detail how they affect the air density in the Duramax system. The stock Borg-Warner variable turbo gets a lot of airtime — Banks accuses it of being "out to lunch" because he feels it's the weakest link on the engine. That turns into a turbo teardown and a deep explanation of performance pitfalls, such as when air pressure on the turbine begins to diverge from the boost pressure coming from the compressor. Banks says he can keep close tabs on where power's coming from, because the iDash monitors the horsepower contribution provided by the ambient air, the turbo, and the intercooler separately. The major changes so far are a stouter Precision 7675 turbo and TurboSmart wastegate (episode 5), a twin intake (episode 6), a custom liquid-cooled intercooler from a marine engine, a new GM oil cooler and synthetic oil (episode 10), and new injectors (episode 11).

2017 GMC Acadia comes into focus

The future slate of crossovers from General Motors reportedly ride on the company's new, scalable Chi platform. With short- or long-wheelbase configurations possible, the chassis conceivably allows the automaker to be more adaptable in the configuration of its CUVs. Cadillac already appears to be testing Chi for the luxury brand's future SRX/XT5, and here it is again under heavy camouflage underpinning the next GMC Acadia. Unfortunately, the Acadia is so well concealed here that it's extremely difficult to pick out any of the styling changes, though the squared-off fenders and faint GMC logo peaking through the tape on the front wheels reveal what this vehicle is. Up front, the grille appears to sit somewhat lower than the current model, and the vertical LED running lights are easy to pick out. The orientation of the taillights through the camo suggests wraparound units not too dissimilar from the current Acadia (or is that Saturn Outlook?). The next-gen Acadia is expected to debut in 2016 as a 2017 model year vehicle. The powertrain options may include the current 3.6-liter V6, a four-cylinder and possibly even a turbo V6, and GM's new nine-speed automatic might also be for offer. With a year before the reveal, take a look at these photos for a first look. Featured Gallery GMC Acadia Spy Shots View 12 Photos Image Credit: KGP Photography Design/Style Spy Photos GMC Crossover gmc acadia

2019 GMC Sierra AT4 First Drive Review | Off-road overkill

The road ahead is dirt with a rut here and a rock there. Brush keeps a respectable distance on the right side, the edge on the left gradually falls away into the valley below. The grade is nothing your treadmill couldn't duplicate and traction is pretty good. Honestly, a couple in their Subaru Crosstrek could pop up here for a picnic. The 2019 GMC Sierra AT4 we're driving is therefore complete overkill. But at least it looks the part as it trudges up this uncharacteristically verdant mountain with San Diego in the distance to the north and Mexico to the south. Its special, dechromed AT4 grille has a purposeful appearance, but tastefully lacks the show-off machismo of Ford and Ram's off-roading models. The red tow hooks are a nice touch and the dark-accented 20-inch wheels wrapped in all-terrain rubber are just the right size beneath a suspension that is raised an extra 2 inches from every other Sierra. That would be one of the key elements that differentiates the AT4 as the Sierra's off-roading model – GMC's answer to the Chevy Silverado's Trail Boss trims. In fact, their mechanical enhancements are identical. Besides the 2-inch lift, the suspension features off-road-tuned Rancho monotube shocks. There's also a locking rear differential, a two-speed transfer case, skid plates and those tow hooks. The 5.3-liter V8 with Dynamic Fuel Management is similarly standard, but unlike the Silverado Trail Boss, the Sierra AT4 offers the 6.2-liter V8 good for 420 horsepower and 460 pound-feet of torque as a roughly $2,500 option. That's the engine we have and it delivers the expected punch, complete with a satisfyingly snarling exhaust note. However, as observed in back-to-back drives with these two available engines during the Silverado launch, the 6.2 certainly isn't necessary. The 5.3-liter is seriously capable and the bigger engine is largely for those who want to have the biggest number possible emblazoned on the fender. It's overkill, which in this particular environment, is fitting. Besides the available engine upgrade, the AT4 also goes beyond its Trail Boss counterpart by dipping into the Sierra Denali's tool box. Its MultiPro tailgate is standard equipment, allowing for six different configurations, the most notable of which include a means of more easily reaching into the bed and a drop-down step that eases entry into the bed. GMC's considerable touting of that last element is rife with hypocrisy given GM advertisements that mocked Ford's similar feature.