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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.

Best and Worst GM Cars

Oh yes, because we just love receiving angry letters from devoted Pontiac Grand Am enthusiasts, we have decided to go there. Based on a heated group Slack conversation, the topic came up about the best and worst GM cars. First of all time, and then those currently on sale, and then just mostly a rambling discussion of Oldsmobiles our parents and grandparents owned (or engineered). Eventually, three of us made the video above. Like it? Maybe we can make more. Many awesome GM cars are definitely going unmentioned here, so please let us know your bests and worsts in the comments below. Mostly, it's important to note that this post largely exists as a vehicle for delivering the above video that dives far deeper into GM's greatest hits and biggest flops, specifically those from the 1980s and 1990s. What you'll find below is a collection of our editors identifying a best current and best-of-all-time choice, plus a worst current and worst-of-all-time choice. Comprehensive it is not, but again, comments. -Senior Editor James Riswick Best Current GM Vehicle Chevrolet Corvette We were flying by the seats of our pants a bit in this first outing and my notes were similarly extemporaneous. When it came time to tie it all together on camera, I failed spectacularly. Thank the maker for text, because this gives me the opportunity to perhaps slightly better explain my convoluted reasoning. I chose the C8 Corvette because it's simply overwhelmingly good, and it's merely the baseline from which this generation of Corvette will be expanded.  While the Cadillac CT5-V Blackwing (more on that in a minute) is an amazing snapshot of GM's current performance standing and its little sibling so enraptured me that I went out and bought one, their existence is fleeting. Corvette will live on; forced-induction Cadillac sport sedans, not so much. So while all three are amazing machines when viewed in a vacuum, the Corvette stands above them as both a reflection of GM's current performance credentials and a signpost of what is to come. So, given the choice between the C8 and the 5V-Blackwing right now, I'd choose the C8. In 10 years, when the Blackwing is no longer in production and Corvette is in its 9th generation? Well, that might be a different story. Now, just pretend I said something even remotely that coherent when we get to the part of the video where I try to make an argument for the 5-V Blackwing as best GM car I've ever driven. Or just laugh at me while I ramble incoherently.

Submit your questions for Autoblog Podcast #323 LIVE!

We're set to record Autoblog Podcast #323 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.
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