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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 to get own model not shared with Chevy?

For years, GMC has existed as a brand without a single unique product, reconstituting Chevrolet trucks, SUVs and crossovers with more frosting in exchange for a few extra dollars. The Sierra is a Silverado, the Acadia a Traverse, and the Terrain an Equinox, although admittedly the latter pair are visually differentiated to a significant degree.
GMC could be set to expand beyond its Chevy-based roots, though. During last week's Detroit Auto Show press days, GM's product boss Mark Reuss was asked whether there'd ever be a GMC that wasn't taken from Chevy. "Oh, yes, you will," Reuss told the media. "The health of GMC is astonishingly good from a consideration standpoint." Reuss wouldn't elaborate on what the model could be, although we're quite happy to make some guesses. GMC has its bases fairly well covered, with a mid-size and full-size crossover, as well as a mid-size, full-size and HD pickup. We doubt GMC will be building a family sedan, sports car, or hatchback, so really, the only place we can see the brand going is into a smaller crossover.
Automotive News points out that the most recent small GMC showcar, the 2010 Granite concept (shown above), won't see production according to General Motors. That vehicle likely would have rode on GM's compact vehicle architecture, known internally as Gamma II, which underpins the Chevy Spark and Sonic, as well as the Buick Encore (and its overseas Opel/Vauxhall/Chevy counterparts).

Chevy and GMC trucks get CNG option pricing

Chevrolet and GMC have clued us in to pricing of the bi-fuel option for the 2015 Silverado and Sierra 2500HD CNG and 3500HD CNG pickups: it starts at $9,500; we're still missing the rest of the pricing inferred by the word "starts," however. If you remember from the Chicago Auto Show introduction, the 6.0-liter V8 puts out 360 horsepower and 380 pound-feet of torque when drinking gas, 301 hp and 333 lb-ft when inhaling CNG.
Chevrolet figures that a bi-fuel Silverado HD is worth $2,000 in savings if driven 19,500 miles on CNG and 7,500 miles on gasoline in the span of a year, a recoup rate easily attainable to high-mileage fleet owners. It can be specced on double- and crew-cab pickups with single rear wheels, not on dualies.
The 2015 Chevrolet Express and GMC Savana short-wheelbase passenger and cargo vans also get CNG options, starting at $10,825 for the three-tank system, and $12,090 for the four-tank system that can only be had on the cargo hauler. You'll find a bit more info on all of the permutations in the press release below.