February 2007 4x4 News - Drivelines

As we've reported for the past few months, all the Detroit 3 truckmakers have had to retool their diesel engines in the wake of changing emissions regulations. Ford and General Motors have gone a step further and timed the release of new 3/4- and 1-ton trucks to coincide with the new powerplants.

It's already 2008 for Ford, as its new Super Duty trucks are labeled '08 models. The new Supers have been restyled on the outside, refined where the rubber meets the road, and even include a new model: the F-450. Intended for serious towing, the dualie-only F-450 utilizes the solid-axle/coil-spring/radius-arm front suspension from the medium-duty F-450 chassis cab and new, longer leaf springs in the rear. The F-450's max payload rating is 6,120 pounds for the 4x2, 5,720 pounds for the 4x4, figures about 300-400 pounds over the F-350 dualie. Its max tow capacity (with a fifth-wheel/gooseneck) is 24,500 pounds with either drivetrain, compared to 18,800 for the F-350 dualie.

The new Super Dutys are available with the 300hp/365-lb-ft 5.4L Triton gas V-8; the 362hp/457-lb-ft 6.8L Triton gas V-10; and the new 6.4L Power Stroke turbodiesel V-8, rated at 350 hp at 3,000 rpm and 650 lb-ft of torque at 2,000 rpm. To meet new emissions regulations, the Power Stroke is outfitted with Ford's "Clean Diesel Technology," which includes a high-pressure, common-rail fuel system, Piezo-electric fuel injectors and a diesel particulate filter in the exhaust. From a driveability standpoint, the diesel's acceleration has been improved over the outgoing engine through the use of two sequential turbochargers-a small, variable-geometry turbo that comes on at low engine speeds, and a larger, fixed-geometry turbo that works with the smaller turbo in the mid-range and takes over at high revs. According to Ford, the new Power Stroke is more than a full second quicker from 0 to 60 mph.

Designwise, the new Super Dutys feature a much taller grille than the old models, a styling feature that also improves engine cooling. The trucks come with some interesting exterior options, including a 300-pound-capacity tailgate step that folds out from the 'gate's top rail; and a polypropylene bed extender that, when not in use, separates into two pieces that fold into the bed sides. Trailer towers will also appreciate the new power-folding and -telescoping side mirrors.

The Super Dutys will be available in regular-, Super-, and Crew-Cab configurations, and with 6.75- or 8-foot cargo boxes, though regular cabs will get the long box only.

Like Ford, GM has given its Chevrolet Silverado and GMC Sierra HD pickups styling features that distinguish them from the light-duty trucks. And like Ford, GM has a new diesel engine in its quiver-a 6.6L Duramax turbodiesel V-8 that's rated at 365 hp and 660 lb-ft of torque. A single, variable-geometry turbocharger boosts the Duramax's performance throughout the rev range, while a diesel particulate filter scrubs the exhaust to help it meet the new smog laws.

Also interesting, though, is something GM doesn't offer this year: a big-block gas engine. The only other engine choice for the '07 HDs is a Gen IV 6.0L gas small-block V-8 that puts out 353 horses and 373 lb-ft of torque. It's a techy motor, with variable-valve timing that improves both low-end torque and high-rev horsepower. But it can't match the 450 lb-ft of grunt that last year's Vortec 8100 big-block offered. So buyers who need abundant torque will have to opt for the Duramax.

The HD truck chassis are equipped with short/long-arm front suspensions and torsion bars, and a solid-axle/leaf-spring setup in the rear with either two- or three-stage spring packs. The Z71 4x4 suspension option package will be available on HD models for the first time.

The HDs will be available in regular-, extended-, and Crew-Cab configurations, and with 6.5- and 8-foot cargo boxes.

Some of the features introduced on GM's new-generation light-duty pickups are carried over to the heavy-duty models, including the optional cargo-management system with adjustable tie-down points. The HDs also receive GM's two-tier interior schedule. Silverado LT, Sierra SLE, and the Chevy/GMC WT models get the "pure pickup" interior, while the higher-end Silverado LTZ and Sierra SLT get the luxe interior with a distinct instrument panel, heated leather seats, and special dash trim.