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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).

GMC Terrain adds AT4 trim, completing the set

"AT4 all of the things!" is GMC's new rallying cry, as the brand has announced that the off-road-themed trim level is coming to the GMC Terrain midsize SUV. The Terrain will join the just-announced 2021GMC Yukon and the 2021 GMC Canyon midsize pickup, both of which add an AT4 variant for the first time. The model designation was introduced on the Sierra full-size pickup for 2019, and spread to the Sierra HD and to the Acadia three-row crossover for 2020. AT4 content, however, varies widely by model. In the Sierra full-size pickup, the trim level brings a full slate of off-road gear including a two-inch suspension lift, a two-speed transfer case for the 4WD system, a locking rear differential, hill-descent control, Rancho shocks, skid plates, off-road tires, and more. The Acadia AT4, meanwhile, includes little more than standard AWD, black wheels and exterior trim, and all-terrain tires. It sounds like the Terrain AT4 will be closer to the Acadia in execution, with GMC promising a black-chrome grille and exterior design elements plus "confident capability and advanced technology." Hmm. The GMC Terrain AT4 doesn't arrive until the 2021 model year, which means this fall, so more specifics, including pricing, are still to come. But GMC couldn't wait to show the Terrain AT4, which completes the AT4 family photo seen above. Related Video:    

NHTSA upgrades probe into 1.7 million GM vehicles over wiper failures

WASHINGTON — The U.S. National Highway Traffic Safety Administration (NHTSA) said Tuesday it is upgrading an investigation into 1.7 million General Motors vehicles for windshield wiper failures. The auto safety agency opened the probe in November 2018 to see if GM needed to expand a 2016 recall of 2013 model year Chevrolet Equinox and GMC Terrain SUVs to cover additional vehicles. The engineering analysis probe covers 2010-2012 and 2014-2016 Equinox and Terrain vehicles. NHTSA could demand a recall after it completes the probe. NHTSA said it has reviewed 1,900 complaints and reports related to the issue in the 1.7 million vehicles. NHTSA said it has seen elevated failure rates in the 1.7 million vehicles, even though GM said the recalled vehicles have "double the warranty rate and five times the complaint rate." GM said it will "fully cooperate to support their investigation. We do not believe these windshield washer systems are defective." The wiper failures that prompted the 2016 recall were attributed to water and debris intrusion into the windshield wiper assembly ball joints, leading to excessive wear and eventual detachment of the ball joint. GM said it was installing an improved windshield wiper motor and transmission assembly and relocating a drain hole at the base of the windshield. Related Video: