1998 Gmc C1500 Sierra Extended Cab 6.5 L Diesel on 2040-cars

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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.

Supercharged 2015 GMC Yukon Denali sounds evil, runs 0-60 in 4.5 seconds

Speeding along in a sports car is undoubtedly a ton of fun, but some owners need the ability to carry a lot of people and their stuff and don't want to sacrifice the ability to put the power down. The tuners over at Hennessey have that demographic covered with their growling, supercharged power kits for the GMC Yukon Denali. The upgrades come in three forms for the SUV's 6.2-liter V8: HPE550 with 557 horsepower, HPE600 with 605 hp and HPE650 with 665 hp. This video showcases the full-bore version, and this Denali can definitely hustle in a straight line. The power bump comes courtesy of a 2.9-liter supercharger, intercooler and high-flow cylinder heads to add over 200 horsepower compared to stock, and the final result is a bellowing SUV that rears up off he line to throw the driver back into the seat. The sprint to 60 miles per hour lasts just 4.5 seconds. Check out this hasty hauler in action in the video above.

GM diesel pickups first to undergo extra EPA, CARB testing

The effects of Volkswagen's long-running diesel emissions evasion are starting to spill over to other automakers, but General Motors is taking things in stride. The 2.8-liter, four-cylinder Duramax in the 2016 Chevrolet Colorado and GMC Canyon is the first engine to get extra scrutiny by the Environmental Protection Agency and the California Air Resources Board, Automotive News reports. Rather than just the usual in-lab test, it's also being checked on the road. However, the extra evaluation shouldn't have any impact on when the trucks with his mill hit dealers later this fall. "We're in our final stages of the EPA certification, and our launch is on track," Chevy spokesperson Otie McKinley tells Autoblog. The four-cylinder diesel in the trucks makes 181 horsepower and 369 pound-feet of torque, and the automaker is touting low NOx production. In the announcement for the Colorado's specs, the company calls it "the cleanest diesel truck engine ever produced by General Motors." The tech includes exhaust gas recirculation to lower combustion temperatures and improve emissions. There's also a urea tank like on the bigger diesels for full-size trucks, and it gets refilled in time with oil changes. An indication on the instrument panel lets drivers know when that's needed, too. Even with the more demanding testing, the company doesn't seem too worried about the four-cylinder passing. "Part of our development process is on-road and off-road [laboratory] testing," Scott Yackley, Chevy Trucks assistant chief engineer, said to Automotive News. In the wake of the VW scandal, the EPA has pledged more rigorous testing. Before, on-road emissions evaluations were largely limited to heavy-duty vehicles, but the agency has decided to apply the checks more often to other models. There's also now greater cooperation with Canadian authorities.