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Submit your questions for Autoblog Podcast #313 LIVE!

We record Autoblog Podcast #313 tonight, and you can drop us your questions and comments regarding the rest of the week's news via our Q&A module below. Subscribe to the Autoblog Podcast in iTunes if you haven't already done so, and if you want to take it all in live, tune in to our UStream (audio only) channel at 10:00 PM Eastern tonight.
Discussion Topics for Autoblog Podcast Episode #313
2014 Chevrolet Silverado and GMC Sierra introduced

Chevy's 6.6-liter Duramax is pretty much all new

To say there's a heated battle in heavy-duty pickups is an understatement, with Chevrolet, Ford, and Ram constantly trading blows of increased torque, horsepower, and towing capacity. The latest salvo is the revised, more powerful turbo diesel 6.6-liter Duramax V8 in the 2017 Chevy Silverado. It has 910 pound-feet of torque, an increase of 145, putting it nearly level with the Ford Super Duty. Here's a closer look at where those gains come from. How exactly did Chevrolet add all that torque plus 48 horsepower? The automaker essentially took a fine-tooth comb to the entire engine. Chevy says it changed 90 percent of the V8, and the cumulative effect of those small changes adds up to big increases. As you might guess, the turbocharger is updated. The larger unit features electric actuation of the variable nozzle turbine (VNT), and what Chevy calls a double axle cartridge mechanism that separates the VNT moving parts from the housing. That helps with heat performance as well, with a claim that the exhaust side of the turbo can run continuously up to 1,436 degrees Fahrenheit. Helping that cause are six exhaust gaskets made of Inconel - an nickel alloy that contains chromium and iron – and upgraded stainless steel for the exhaust manifold. Despite having the same cast iron cylinder block, albeit with some minor enhancements, the engine has new cylinder heads, pistons, piston pins, connecting rods, and crankshaft, which have all been upgraded to handle 20 percent higher cylinder pressures. Alongside the increase in pressure, Chevrolet also increased the cylinder head's structure with a honeycomb design. The pattern features high-strength aluminum with dual layer water jackets that not only improve strength, but also optimize water flow for better cooling. For 2017, the cylinder head also benefits from integrated plenum that aids the engine in getting more air under heavy loads. The cylinder head isn't the only component to get a minor update, as the pistons have a larger diameter pin for improved oil flow. The same detailed improvements has been bestowed to the humble connecting rods (second in our hearts only to the inanimate carbon rod). The new design has the bolts oriented roughly 45-degrees to the rod instead of parallel. The angle split design, as it's called allows for easier passage through the cylinder.

GM resumes production of its 3.0-liter turbodiesel straight-six

General Motors temporarily stopped taking orders for trucks and SUVs equipped with the 3.0-liter Duramax turbodiesel six-cylinder engine in August 2021 due to a supplier shortage. Reports claimed the pause would last through 2021, but the engine is already back in production. Enthusiast website GM Authority learned from sources inside General Motors that the straight-six is once again coming off the assembly line at the Flint Engine Plant in Flint, Michigan. There's no official word on precisely what the problem was linked to and whether it was related to the on-going chip shortage that's wreaking havoc across the automotive industry. All we know is that the pause lasted for about two weeks. Called LM2 internally, the six is available in Chevrolet's Tahoe, Suburban, and Silverado 1500 and in GMC's version of these trucks. It's also an option in the Cadillac Escalade. It develops 277 horsepower at 3,750 rpm and a V8-like 460 pound-feet of torque at 1,500 rpm in every application, and it allows these big behemoths to post surprising fuel economy numbers. Fitted to a rear-wheel-drive Tahoe, the Duramax returns 21 mpg in the city, 28 mpg on the highway, and 24 mpg in a combined cycle, figures that make it more efficient than a Blazer. Demand for the diesel-powered trucks is relatively high. While the shortage undoubtedly took a toll on sales, the Duramax represented 8% of Suburban sales and 6% of Tahoe sales in May 2021. There are no other diesel-burning full-size SUVs available new so they have the market to themselves. On the truck side, Ram still makes the EcoDiesel available on some 1500 trims but Ford abandoned the segment. Related Video: Featured Gallery 2021 Chevrolet Tahoe RST View 24 Photos Chevrolet GMC Truck SUV Diesel Vehicles