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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.

GM delays 3.0-liter Duramax diesel in Silverado and Sierra pickups

Stricter testing protocols around the world are making it harder for automakers to predict launch timelines. GM is the latest to get caught in emissions nettles, the Detroit carmaker forced to delay the launch of its new Duramax 3.0-liter inline-six diesel for the Chevrolet Silverado 1500 and GMC Sierra 1500. That's what company reps told dealers in a memo seen by Automotive News this week. Dealers and buyers had been promised the Flint, Mich.-built oil-burner in early 2019, but AN wrote that the EPA certification hiccup has turned into a "slight delay." A GM spokesman told Motor1, "[We] did not attribute [the delay] to a single entity, as the truth is this is a collaborative effort between GM and several government entities. We will make the 2020MY Duramax available for dealers orders soon, and expect to deliver the first trucks to customers soon after emissions testing is complete." We know the new 3.0-liter Duramax diesel has 277 horsepower and 460 pound-feet of torque, outdoing Ford's 3.0-liter PowerStroke diesel by 27 hp and 20 lb-ft. But without final EPA paperwork, GM can't release the numbers that will show how the two engines stack up when considering fuel economy and tow ratings. The certification process has been sticky for a few other makers of late, especially since the Volkswagen Group situation in 2015. BMW had to delay the launch of four diesel models in 2016 over EPA testing. The new Ram 1500 dribbled out in a trickle last year for reasons thought to deal with EPA testing, coming as it did a year after the EPA investigated Ram's EcoDiesel engines in 2017 and 2018. More recently, WLTP testing in Europe caught out just about every automaker over there. Since we're almost halfway through 2019, the delay until the 2020 model year is only a few months. Still, GM told dealers to cancel any orders for the engine for this model year. Dealers will need to resubmit the orders once opening begins, but GM hasn't said when production will begin other than "soon." The company said that it will offer 2020-model-year replacement vehicles to customers and dealers. If prices hold into the next model year, the 2020 Silverado 1500 and Sierra 1500 with the inline-six diesel will come at a $3,890 premium over the 2.7-liter turbo four-cylinder, and a $2,495 premium over the 5.3-liter V8.

GM threatens predatory dealers with order cancellations, non-transferrable warranties

General Motors will launch a second salvo against misbehaving dealerships next week with a new set of policies aimed at curbing predatory markup strategies. With the new Chevrolet Corvette Z06, GMC Hummer EV SUV and Cadillac Escalade-V about to head into production, GM is putting its foot down yet again. Dealers that attempt to circumvent GM's markup restrictions by dealing directly with brokers or other resellers could find themselves in a particularly nasty spot, as the company is threatening to withhold future allocations and end the transferability of warranties when dealers facilitate the reselling of vehicles within 12 months.  While this may help curb some dealership chicanery, it's possible the real loser in such a deal could end up being the customer who unwittingly ends up with an un-warrantied vehicle. We suspect GM has accounted for that, but we'll have to wait until next week to find out exactly how these new policies will be enforced.