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[SILVERadoTACOMA]

GM's finally fighting back?

Let’s start with the Sierra Denali’s power and drivetrain. There’s been considerable gnashing of teeth from domestic pickup fans because Toyota’s remade 2007 Tundra was the first and only half-ton to offer a six-speed automatic gearbox and the most powerful gas engine in a standard duty pickup. The small block 5.7-liter iForce DOHC V8 engine in the Tundra is rated at 381 horsepower and 401 lb-feet of torque. But Tundra’s brief reign as power king is over, because the Sierra Denali checks the Tundra’s tranny with its 6L80E six-speed shifter and checkmates the iForce with GM’s mighty Corvette-inspired 6.2-liter L92 Vortec V8. The quasi big block pounds out 403 horsepower and 417 lb-feet of torque. The L92 and 6L80E are GMC exclusives this year but all GM light duty pickups will start to replace their four-speed 4L80E transmissions with the 6L80E in the 2008 model year, as build capacity increases. The Vortec meets other iForce powertrain advances head-on to also offer variable valve timing (another Sierra Denali first for a pickups with pushrod engines) for both the intake and exhaust valve timing. VVT helps bump up torque on the low end and horsepower on the high end. More on this later.

Now, let’s give these figures some perspective through a virtual drag contest against the Toyota. Edmunds.com timed a 2007 Toyota Tundra Double Cab 4x4 with the 5.7-liter iForce with almost identical results. For both trucks the quarter mile and 0 to 60 times are the same, but the Sierra Denali finished .2 miles per hour faster than the 93.7-mph scored by the Tundra. Where it gets interesting is that the Denali is geared for better fuel economy targets while the Tundra is geared for better towing performance. The Denali’s final drive ratio is a stocky 3.42:1, to help push up its CAFE scores, but the 6L80E’s broad range compensates by using an extremely low 4.03 first gear and VVT to ensure quick starts off the line. The tested Tundra had a much lower 4.1 rear axle ratio, as it was optionally equipped with a trailering package to tow a hefty 10,400-lbs - 1,700-lbs more than the Denali - and it used a 3.33 first gear for launch. One final consideration, the Denali ran the track shod with 20-inch chromed dubs while the Edmunds Tundra used 18-inch wheels.

Huge drawback.... I'd be willing to bet this baby comes in at 45K +

http://www.pickuptruck.com/html/2007...est/page1.html