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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).

2020 GMC Acadia refresh brings a new engine, AT4 trim level

It's mid-cycle refresh time for the GMC Acadia, and the updated 2020 model kicks off its changes with a new face. It has a square-jawed grille seemingly pulled straight off the Sierra full-size pickup, and the size is amplified by the slender new LED headlights on either side. At the rear, the LED taillights are taller and more chiseled. A new AT4 trim level adds more visual distinction with black trim and wheels, plus all-terrain tires to make it a little more capable off road. The AT4 also boasts standard all-wheel drive. Under the revised skin, the Acadia hides one of two carryover engines, or a new turbocharged 2.0-liter inline-4. This new engine makes 230 horsepower and 258 pound-feet of torque with the help of a twin-scroll turbocharger. To make it more frugal, it's able to deactivate two of its four cylinders. The turbo engine is standard issue on the SLT and Denali trim levels. The carryover engines include a naturally aspirated 2.5-liter 4-cylinder making 193 horsepower and 188 pound-feet of torque, and a naturally aspirated 3.6-liter V6 making 310 horsepower and 271 pound-feet of torque. The V6 is standard equipment on the AT4 trim. No matter the engine, all 2020 Acadias get a 9-speed automatic transmission. The new transmission also ditches the current Acadia's mechanical shift lever in favor of an electronic shifter with the Terrain's mix of buttons and triggers. It does free up space between the seats, but the button arrangement is still as strange as it was when we first saw it in the smaller crossover. There are a handful of other little upgrades to mention. The suspension has been revised for greater comfort; the infotainment has been revised with a bigger screen, USB-C inputs and customizable profiles; and wireless phone charging is now an option. The updated Acadia goes on sale this fall, and pricing will probably be announced close to launch.

Watch GM's new pickup crash its way to five-star NHTSA ratings

General Motors has just scored a big win with its Chevrolet Silverado and GMC Sierra pickup trucks, acing the National Highway Traffic Safety Administration New Car Assessment Program. The two full-size trucks had already netted a five-star Overall Vehicle Score in their crew-cab variants, but the new testing certifies them as five-star trucks in both regular and double-cab bodystyles, so GM's trucks offer top ratings across the board.
"Our incredibly capable trucks have been engineered to be some of the safest," Gay Kent, GM's general director of Vehicle Safety and Crashworthiness said. "We've designed the vehicle structure, strategically placed high-strength steel and developed the occupant restraint system to achieve high levels of safety performance."
The scores mark the Silverado and Sierra as the first pickups to net five-star scores since NHTSA beefed up their testing regime in 2011, a nice feather in GM's cap as it continues to slug out the pickup truck wars with crosstown rivals Ford and Ram.