2011 Chevrolet Traverse Lt Sport Utility 4-door 3.6l 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.

Watch this week's Top Gear America used-car challenge

Top Gear America is back for the penultimate episode of the first season. Used car challenges were some of the highlights of the original UK edition. In our exclusive clip, Tom Ford, Antron Brown and William Fichtner run their $7,000 sports cars in a drag race. As expected, the trio chose very different cars for the challenge. Watch the video to see if a Subaru WRX's all-wheel drive can overcome a power deficit to beat a Ford Mustang and a Chevy Corvette. Brown and Fichtner also spend some time relaxing with an old Jeep Wagoneer. Like them, we're really hoping Jeep will bring back the Wagoneer nameplate. Brown also drives a Maserati Levante, proving that not all family cars need be boring. This week's guest star is actor, rapper and former host of Pimp My Ride, Xzibit. Top Gear America airs Sundays at 8 p.m. Eastern on BBC America. Related Video: Celebrities TV/Movies Chevrolet Ford Subaru Top Gear exclusive top gear america

Weekly Recap: Electric Rapide concept showcases Aston's future

Aston Martin showed off an all-electric Rapide S prototype this week and announced an agreement with investment firm ChinaEquity to explore development of a production version of the sports sedan. The car could arrive in about two years if the project advances, and it would be built in Gaydon, England. The concept car, called the "RapidE" was developed with Williams Advanced Engineering. The electric Rapide is meant to highlight British innovation, and it was revealed during a state visit by Chinese president Xi Jinping to the United Kingdom. Spec were not available for the concept on display. "The car we showed in London is a fully running concept but not yet defining [of] our choice of battery, motor, inverter, etc," spokesman Simon Sproule said. "Now that we have a clearer path for producing the car, we will be defining all the parameters." Aston Martin has been vocal about its electric ambitions this year, and Sproule told us at the New York Auto Show that an all-electric Rapide could cost $200,000 to $250,000 or more. "It's a study, but we're serious about it," he said. Some reports have indicated the electric Rapide could pack as much as 1,000 horsepower. Aston considers electric technology the strongest play for modernizing its powertrains and meeting emissions standards around the world. Hybrids and all-electric models can offer high outputs and strong torque delivery, which is in keeping with the Aston's image as a sportscar maker. Company brass prefer this option over dropping down to four-cylinder engines. And yes, V8s and V12s remain part of the plan. The electric push is part of Aston's future strategy to remake its lineup, which includes refreshing its sportscars, building a production version of the electric all-wheel-drive DBX concept shown at the Geneva Motor Show, and adding a four-door Lagonda. OTHER NEWS & NOTES Domino's serves up purpose-built delivery car Domino's revealed a purpose-built pizza delivery car based on the Chevy Spark. It's called the DXP, for Delivery Expert, and it can handle up to 80 pizzas. The pies stay warm thanks to an oven located behind the driver's seat, and the DXP is sauced up with a puddle-lighting feature that projects the Domino's logo outside of the car. Power comes from the Spark's stock 1.2-liter four-cylinder engine rated at 84 hp that gets up to 39 mpg on the highway. Chevy dealers will be trained to service the DXP.