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GM considering new powertrain options for large SUVs

Aside from the new General Motors offerings, there's not a whole lot of action going on in the fullsize SUV segment. That doesn't seem to be stopping GM from pushing the envelope in the market as Automotive News is reporting that the automaker is looking to introduce some new powertrain options into the Chevy Tahoe (and Suburban), GMC Yukon (and Yukon XL) and the Cadillac Escalade - all have been redesigned for the 2015 model year.
Now, we already know that GM and Ford are collaborating on nine- and ten-speed transmissions for a broad range of applications (including the big SUVs), but this new report says that GM is also considering other options as a way to one-up the competition and, of course, to optimize fuel economy. AN quotes Jeff Luke, executive chief engineer for GM trucks, as saying that "interesting powertrain technologies" are coming including a return of a hybrid SUV and possibly even a diesel engine. Although it sounds like the latter could come down to how customers respond to the 2014 Jeep Grand Cherokee EcoDiesel.

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.

370,000 new Silverado and Sierra pickups recalled over fire risk

General Motors announced late Friday that it will recall around 370,000 Chevrolet Silverado and GMC Sierra fullsize pickups from the 2014 model year over a possible fire risk. The recall covers select 4.3-liter V6 and 5.3-liter V8 models, which can evidently suffer engine compartment fires due to the overheating of exhaust components. GM notes that the fire issue may be preceded by a check engine light and an "engine power reduced" message on the driver information display.
Thus far, GM is aware of eight fires stemming from this problem (although only three of those incidents affected customer-owned vehicles), and all of the fires were reported in areas with "very cold weather." GM is urging owners to not leave their vehicles unintended while idling. No injuries have resulted from the fires in question.
The Detroit-based automaker has pledged to start mailing out recall letters on January 16. The fix, which involves software reprogramming, is estimated to be a 20-minute repair, and will be made free of charge.