1955 Chevrolet on 2040-cars

Auto blog

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 announces 3 new recalls affecting 1.7M vehicles in North America [w/video]

Still embroiled in the ongoing ignition switch recall, General Motors announced today three more discrete recalls, affecting a grand total of 1,546,900 vehicles in the US. The Detroit News reports that some 1.7 million vehicles are affected overall in North America. The first and largest of the trio of new recalls concerns some 1.18-million Buick Enclave and GMC Acadia crossovers from the 2008-2013 model years, Chevrolet Traverse from 2009-2013 (pictured above) and Saturn Outlook vehicles from 2008-2010. All of the crossover utilities may have an issue with the wiring harness for their seat-mounted side airbags. Apparently, the vehicles are equipped with a Service Air Bag warning light that, if ignored, "will eventually result in the non-deployment of the side impact restraints." Those restraints include the side airbags, a front-center airbag if the vehicle is so equipped and seatbelt pretensioners. Dealers of affected vehicles will be instructed to remove driver and passenger side airbag wiring harness connectors, and then "splice and solder the wires together." The second recall affects 303,000 Chevrolet Express (pictured right) and GMC Savana vans from model years 2009-2014, and with gross vehicle weights under 10,000 pounds. Said vehicles do not comply with a head impact requirement for unrestrained occupants, and will need a reworking of the instrument panel material to be sent back on the road. It doesn't sound as though there's a quick fix for this one, as the GM press release states: "Unsold vehicles have been placed on a stop delivery until development of the solution has been completed and parts are available." Finally, the third recall affects 63,900 Cadillac XTS luxury sedans from model years 2013 and 2014. A brake booster pump may be susceptible to corrosion by way of the relay, potentially causing and electrical short, overheating, melting of plastic components and even engine fires. GM says it is aware of two engine fires in unsold XTS models and two cases of melted parts. Repairs for the issues affecting the XTS have not not mentioned by GM in the release. The Detroit News is also reporting that along with news of the triple-recall, GM is taking a $300-million credit to help pay for the repair costs, and to deal with the ongoing costs associated with the ignition switch recall. In an attempt to explain just what GM has been doing in the face of these very serious issues, newly minted CEO Mary Barra has addressed the issues in a new video.

Submit your questions for Autoblog Podcast #321 LIVE!

We're set to record Autoblog Podcast #321 tonight, and you can drop us your questions and comments regarding the rest of the week's news via our Q&A module below. Subscribe to the Autoblog Podcast in iTunes if you haven't already done so, and if you want to take it all in live, tune in to our UStream (audio only) channel at 10:00 PM Eastern tonight.
Discussion Topics for Autoblog Podcast Episode #321
Unibody Ford Ranger replacement