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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.

Chevy Colorado, GMC Canyon get updated tachometers due to graphical error

After James Bearing bought a Chevrolet Colorado, he noticed a discrepancy between the truck's spec sheet and the truck's tachometer: Chevrolet said 3.6-liter V6 in the little pickup produces 305 horsepower at 6,800 rpm, but the the tachometer indicates a redline at 6,500 rpm. So either he wasn't making as much power as he was promised, or the tachometer display was incorrect. Bearing said he asked Chevy about it but got no response. Until now. A General Motors spokesman said the rev limiter is indeed set for 6,800 rpm, but the tach graphics "are slightly off" in the Colorado and the GMC Canyon, and submitted an SAE horsepower certification to back him up. If you're wondering how such a thing got past quality control... well, let's just say you're not alone. GM is going to fix "the graphics on future trucks," which makes it sound like Bearing will just have to learn to live with the indicated redline he's got. He could always pretend he's driving a sleeper, with four more ponies waiting to be unlocked in the danger zone for those who dare. Related Video: Featured Gallery 2015 Chevrolet Colorado: First Drive View 38 Photos Related Gallery 2015 GMC Canyon: Quick Spin View 27 Photos News Source: Auto Guide Auto News Chevrolet GM GMC Truck gmc canyon

Could the GMC Jimmy come back as a Wrangler fighter?

Every three or four years, two cars go into heavy media rotation in stories about supposed new competitors. The headlines go something like, "X automaker working on a vehicle to fight the iconic Y." The Y cars are the Porsche 911 and the Jeep Wrangler. For this story, the X automaker is GM. And since GM already has its 911-fighter poised for debut next month, we speak here of the Wrangler. Car and Driver writes that GMC might take another shot at a Jeep challenger, this time by rebirthing a body-on-frame Jimmy SUV. For any who don't know, GMC sold an S-15 Jimmy from 1982 to 2005, a twin of the Chevrolet S-10 Blazer. Those SUVs started their lives as the Chevrolet S-10 and GMC S-15/Sonoma pickups. The Blazer name has returned to the light, albeit without its old-school rugged manners. There's still an opening on the GMC side, though, so C/D says the idea would be to work that old magic on the GMC Canyon pickup. The report is more chaff than grist for the rumormill, with liberal application of phrases like "looking to come up with," "could be," "could take," and "could arrive." Having said that, a potential Jimmy model could come in a few years, could use the same six-cylinder gas and four-cylinder diesel engines as the Canyon, and could start around $30,000. The Jimmy could wear GMC's new mud-and-guts AT4 trim name, or become a mud-and-guts trim for the Canyon just as the ZR2 is for the Colorado. It's not an entirely crazy idea, however, when a body-on-frame Trailblazer SUV based on the Colorado sells in Latin America, Asia, and Australia and does pretty well in the mud and muck. GM's been on the edge of going to war with the Wrangler for at least 12 years, when a Hummer exec said the HX concept would debut at the 2008 Detroit Auto Show and go on sale in 2010 as the H4. In 2015, The Wall Street Journal said GM was canvassing GMC dealers about something to get in the ring with the Wrangler. And all that was before every other automaker had to watch Jeep open a money-counting operation to handle its Wrangler profits, and dealers started charging $20,000 markups on Gladiators. In May, spy shooters caught a sensor-laden Jeep running at GM's Milford Proving Grounds in Michigan. Earlier this month, Bloomberg reported GM is considering a Hummer revival as an all-electric hardcore SUV. So we will not be surprised if GM rolls out a Wrangler fighter in the near-ish future. But we won't be surprised if GM doesn't, either.