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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).

GM recalls 3.8 million vehicles in North America due to braking issue

WASHINGTON — General Motors Co said Wednesday it was recalling 3.46 million U.S. pickup trucks and SUVs to address a vacuum pump issue that could make braking more difficult and that has been linked to 113 accidents and 13 injuries. The recall covers 2014-2018 model year vehicles, including some Cadillac Escalade, Chevrolet Silverado, Chevrolet Tahoe, GMC Sierra, Chevrolet Suburban and GMC Yukon vehicles. In late June, GM recalled 310,000 vehicles in Canada for the same issue. GM did not immediately explain why the Canadian recall occurred more than two months before it called back the vehicles in the United States. The recall was triggered because the amount of vacuum created by the vacuum pump may decrease over time, GM told the National Highway Traffic Safety Administration (NHTSA) in documents posted on Wednesday. The NHTSA opened a preliminary investigation into the issue last November, and said it had reports of nine related crashes and two injuries. It provided GM in July with additional field reports that prompted the automaker to open an investigation. GM said it could affect braking in "rare circumstances." The NHTSA said in a statement the "vehicles may experience brake boost failure, which would require increased brake pedal effort, leading to a hard brake pedal feel, and potentially increased stopping distance." GM said dealers will reprogram the electronic brake control module to improve how the system utilizes the hydraulic brake boost assist function when vacuum assist is depleted. GM said the vacuum assist pump, which is lubricated with engine oil that flows into the pump through a filter screen, can in some cases lose effectiveness over time, as debris such as oil sludge can accumulate on the filter screen. GM told NHTSA that prior model years used a different brake assist system design, and vehicles manufactured after 2018 were not equipped with the affected pump design. Separately, GM said on Wednesday it is recalling 270,000 additional U.S. vehicles in three smaller recalls, including 177,000 2018 Chevrolet Malibu cars with 1.5L turbo engines because an error in the engine control module software may result in the fuel injectors being disabled.

Bob Lutz builds the case for a mid-engined Corvette

Rumors of a mid-engine Corvette are like automotive industry folklore at this point. Every once in a while, news pops up that it might be happening or is under development, but nothing actually ever comes to fruition as something people can actually buy. The latest spy shots strongly suggest a mid-engine 'Vette is in the cards, yet again, possibly for 2018. Now, an op ed by former General Motors executive (and definite performance car fan) Bob Lutz in Road & Track gives the inside scoop on the history of one of these proposals and lays out how to make it happen today. According to Lutz, the company's engineers believed the C6 ZR1 was at the limit for front-engine, rear-wheel drive performance in that package, and the only solution was to move the powerplant behind the driver. Lutz even got then CEO Rick Wagoner on board. The scheme made it at least as far as clay models for mid-engine versions of the 'Vette and Cadillac XLR. Eventually, a lack of money got in the way, though, bringing the project to an end. Lutz puts a lot of faith in GM's current leaders, especially Mary Barra and Mark Reuss. He thinks the chances of a mid-engine 'Vette happening this time are better than 50 percent. The model, rumored to be named Zora, could offer over 700 horsepower in an ultra lightweight body and be priced at about $120,000 to "suck the doors off everybody." Head over to Road & Track to get some insights from this highly respected and entertaining auto industry veteran. Related Video: