Shifting into the future

| November 30, 2006

The 435-horsepower D13 in this VT 660 performed like a bigger engine.

The I in Volvo’s new 12-speed automated I-Shift transmission stands for “intelligent,” and with its many features and smooth, solid feel, the name fits.

Designed for Volvo’s D11, D13 and D16 engines, the I-Shift transmission weighs only 600 pounds but can handle the D16′s 600 horsepower and 2,050 pounds-feet of torque. Its brawny, simple construction looks reliable and tough. The I-Shift is mechanical but fully automated, has no clutch pedal and goes 250,000 miles without servicing.

Like car automatics, the I-Shift lets drivers idle-crawl, which makes parking with an automatic transmission a lot easier and safer. It can all but stop the truck without mechanical brakes, and it skips gears, shifting up or down as necessary. At the driver’s behest, the I-Shift continually measures load, speed and rolling resistance and picks the right gear.

Engine and transmission are from the same family, and understand each other better in this age of “smart” machines, the company says.

This proved true in both my ’07 Volvo engine road tests involving the I-Shift, one with a 435-horsepower D13 in a VT 660 and one with a 500-horsepower D16 in a VT 770.

An old-school, standard-shift man and admittedly skeptical about automatic transmissions for big trucks, I first chose to drive a standard-shift Eaton-Fuller 18-speed double-over gearbox. Its location behind the 600-horsepower, 2,050 pounds-feet torque D16 in a bright yellow VT 880 might’ve persuaded me as well.

The 880 was confined to the former racecar test track on Georgia’s Hutchinson Island. The track is flat, and Volvo’s course included 90-degree turns, “S” curves, sharp bends and straight sections. Like the 660 and 770, the 880 and its loaded, 53-foot dry van weighed about 75,000 pounds. On one straight section, in upper sixth gear at 10 miles an hour and 1,000 RPM, I floored the accelerator, in response to thickening CB scuttlebutt about power and performance loss in ’07 engines compliant with EPA regulations. The D16 nonchalantly grabbed its 37.5-ton payload and surged forward, its big-diesel, heaven-and-earth-moving feel and sound plainly evident. Our speed and RPM doubled in about four seconds: an informal test, but in the United States and now Sweden as well, 600 horsepower and 2,050 pounds-feet of torque in 2007 are as strong as they were in previous years.

Volvo uses exhaust gas recirculation and diesel particulate filters to bring its engines’ nitrous oxide and soot emissions into compliance with the EPA’s ’07 limits. The D11, D13 and D16 engines were all designed around the regulations, so the EGR, DPF and ultra-low-sulfur fuel the engines use have not caused power loss or performance drop.

“Any loss of power from ultra-low-sulfur fuel will only be felt in pre-’07 engines,” says Product Marketing Manager Bo Hammerlid. “The ’07 engines are designed to compensate for that power loss.” Volvo’s only change is the ’07 D16 which produces 2,050 pounds-feet of torque, while the ’06 D16 produces 2,250 pounds-feet. But Volvo says fuel economy in its ’07 engines is 3 percent higher than it’s ’06 engines.

Southeastern Georgia has no natural hills to test an engine’s mettle, but the U.S. Highway 17 bridge joining Hutchison Island with mainland Savannah has steep slopes and is long enough to show pulling power going up and engine brake performance going down. My first test drive was in the Red VT 660 powered by a 435-HP D13. The other test truck would follow. My chaperone/information source for this test was Drivetrain Product Manager Ed Saxman.

In unusually cool, dry weather for September in Georgia, we slowly rounded the steep, sharply curved ramp that merged onto the bridge near the bottom. For safety’s sake I took the ramp at about 20 miles an hour. Once we swung into the straight merge lane on the bridge, Saxman said, “Floor it,” so I did that and steered: no worries about shifting smoothly at low speeds with a heavy load to get speed up on a steep hill. The transmission downshifted two gears while I checked traffic, and we accelerated up the hill.

Conservatively, the bridge is about a 5 percent grade and a quarter to a half mile long on both sides. The D13 and I-Shift combination got us to about 38 miles an hour at the top. Back down the other side, Saxman pointed out the Eco-Roll feature at work. As the 660 coasted, the I-Shift went to neutral and the engine briefly idled. At just a few miles an hour faster, the D13′s powerful Volvo engine brake momentarily kicked in, keeping the truck within set speeds. Eco-Roll is not a “poor man’s overdrive”: with Volvo’s enhanced I-VEB engine brake, the I-Shift’s Eco-Roll maintains driver-set speeds up- and downhill, even with heavy loads.

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