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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.

Next Corvette ZR1 to get 700 horsepower?

Word has it General Motors may offer as much as 700 horsepower in the C7 Corvette ZR1. Motor Trend reports the next Corvette Z06 will continue to rely on its naturally aspirated 7.0-liter V8 engine for thrust, but the lump will deliver substantially more power. How much more? MT says the engine could deliver up to 600 ponies. That's a jump of 95 horsepower over the current Z06, though no figures have been finalized as of yet. Right now, GM is reportedly waiting to see what sort of grunt it can glean from the next ZR1.
The automaker has already made it clear it will resurrect the LT5 name for the new supercharged V8, and if GM is already pulling 600 from the Z06, the big dog ZR1 would theoretically offer 700 horsepower. Either way, the range-topping Corvette will be suitably insulated from its less potent siblings. Stay tuned. We aren't likely to see the Z06 for at least a year, with the ZR1 trailing along at some point there after.

Callaway debuts its new C7 Stingray at National Corvette Museum

Callaway showed off its first tuned version of the 2014 Corvette Stingray at the National Corvette Museum last week, giving the rampant enthusiasts of America's sports car a look at the roughly 620-horsepower, supercharged rocket.
Unlike the Corvette SC610 we showed you back in January, this Stingray packs a fair bit more oomph. Horsepower is only up ten ponies, but torque has jumped from 556 pound-feet to "at least" 600 pound-feet. Neither horsepower nor torque is official quite yet, although Callaway is expecting to know just what its creation can do once testing and validation is completed later this month.
The 6.2-liter, supercharged V8 now boasts a new, three-element intercooler, which Callaway claims only allowed the inlet air temperature to increase by ten degrees Fahrenheit during dyno runs. Previous designs saw a 35-degree-Fahrenheit jump. The exhaust system has also been fettled with, and now is even less restrictive.