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Race Recap: 2013 Twelve Hours of Sebring, cakewalk up front, grindfest out back [w/spoilers]

This year's 12 Hours of Sebring wasn't exactly a foregone conclusion because we're still talking about racing, and anything can happen when the speeds are as high as the adrenaline and the desire. But we're still talking about Audi bringing it's two top-spec racers - and its huge budget and its nearly neurotic attention to detail - to a race that it uses as a test bed for The 24 Hours of Le Mans and as a way to open the endurance racing season with a victory.
Besides, 12 hours is a long time, especially at Sebring, and things didn't go all Audi's way. On top of that, although it was a pretty quiet race, behind the Audis things got even grimier, with plenty of battles, plenty of mechanical issues, and the new BMW Z4 GTE and Viper GTS-R being race tested. Oh, and that brand new chromed-out DeltaWing...

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.

Car Club USA: Louisiana Mudfest

There's nothing quite like mudding. Big tires, huge power, and crazy-wild gearheads that like to throw down on a mud pit almost as much as a thirty rack of Coors. In the latest, and some might argue greatest yet episode of Car Club USA, we head to Louisiana to throw some dirt at Mudfest. As Louisiana's one and only Mouth of the South puts it, "If you don't mud ride... go to Texas I guess." Joining The Mouth and friendly rivals The Most Hated Mud Sluts, we dive in. Beyond the obvious V8 blasting and tractor-tire spinning, those who know best describe Mudfest as, "Good cooking, good friends, good fun, and a lot of partying." It's a motorsport spectacle unlike any you're likely to find up North or out West, though no less impressive to behold. Follow along with the fun, the impromptu drag racing, the trash talking, and the mechanical madness. And find out why, at Mudfest, "if we don't tear it up, we ain't done it right." Each Car Club USA episode features a different car club or event from across the US, where passionate owner communities gather to share automotive experiences and embark on incredible adventures. From Main Street cruises to off-road trails, catch all the latest car club activity on Autoblog. Chevrolet Ford Jeep RAM Truck Off-Road Vehicles Car Club USA Videos autoblog black