GM also offers the Vortec 6.0L V-8 in its new HD pickups. The gas engine has a new cam profile for better low-end torque production, and the 6L90 six-speed automatic behind it has been strengthened with equipment that includes a new output shaft and four new attachment bosses to the transfer case adapter.GM also offers the Vortec 6.0L V-8 in its new HD pickups. The gas engine has a new cam pro GM's engineers also brought a Power Stroke-equipped '11 Super Duty F-250 SuperCrew for back-to-back comparisons. Our initial seat-of-the-pants impression was that there wasn't much difference between the two in terms of power delivery and ability to tow the 41/2-ton trailers. But then the GM guys instigated a couple of impromptu towing drag races, with the Silverado and Super Duty sprinting side-by-side to the top of a hill. The Chevy always got the hole shot and was first to the top, lopsided victories that make the Duramax's power advantage seem even bigger than it is on paper. The difference between the two became even more pronounced as we headed down that hill. GM has developed an (optional) exhaust brake system that uses the variable-geometry vanes in the single turbocharger to create exhaust backpressure. With cruise control engaged, the exhaust brake and the cruise control maintain the desired speed. When not in cruise, the Allison transmission and the exhaust brake work together to keep downhill speeds in check. We found that a light tap on the brake pedal was all it took to engage the GM's brake, while in the Ford it sometimes took two or three pushes on the pedal. And when exhaust braking did start, it wasn't as nicely matched with the truck's downshifts as was the case with the Allison. There's not much in here that screams "work truck," is there? The heavy-duty GM pickups are just as well-appointed inside as their light-duty brothers. We like that GM's trucks are fully instrumented and offer high-end options like navigation systems. We don't like having to hunt around on the instrument panel for things like 4WD engagement. In one truck we drove, the heater and A/C control was blocked by the transmission lever when it was in Drive. Ergonomically, these trucks still need some help.There's not much in here that screams "work truck," is there? The heavy-duty GM pickups ar But really, the fact that we're talking about exhaust brakes at all takes us back to our original point: All of these trucks, regardless of make, are well-equipped to handle just about any chore you want to throw at them, while offering interior appointments and comfort unheard of in this category just a few years ago. But until we undertake that three-way comparo, we have to acknowledge that GM's HD offerings, at least on paper, are head of the class. Tech Specs 2011 Chevrolet Silverado HD & GMC Sierra HD Drivetrain Available engines: Vortec 6.0L V-8, 360hp and 380 lb-ft.; Duramax 6.6L diesel V-8, 397 hp and 765 lb-ft. Available Transmissions: Hydra-Matic (6L90) 6-speed auto (w/ Vortec), Allison 1000 6-speed auto (w/ Duramax) Chassis Front Suspension: Long-short-arm independent w/ torsion bar Rear Suspension: Semielliptical 2-stage multileaf spring Brakes: 4-wheel disc w/ ABS Min. Ground Clearance: 8.2 in (2500 4WD crew cab) Capacities 2500 Series Max. Payload, 4WD: 3,580 lb (gas reg. cab long-bed) Max. Conventional Towing, 4WD: 13,000 lb (diesel & gas, all configs) Max. 5th-Wheel Towing, 4WD: 17,500 lb (diesel reg. cab long-bed) 3500 Series Max. Payload, 4WD: 6,308 lb (gas reg. cab long-bed dualie) Max. Conventional Towing, 4WD: 17,000 lb (diesel reg. or ext. cab dualie) Max. 5th-Wheel Towing, 4WD: 21,700 lb (diesel reg. cab long-bed dualie) « | 1 | 2 | View Full Article By Drew Hardin Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!