The 16 percent grade was where we separated the men from the boys. Inclinations this steep expose even the slightest powertrain and platform weaknesses. And there was almost no time for a truck to recover and mask any shortcomings in its powertrain or driveline during the brief 800-foot run. Most of the gas trucks couldn’t make it out of first gear. The diesels only made it to second gear, except the Sierra Denali 3500HD, which made it to third.
Three-Quarter-Ton Gas Trucks Towing 10,000-Pound Trailer
If any test turned our opinion around about Ford’s 6.2-liter V-8, it was the 16 percent grade. We haven’t embraced it like Ford’s old 6.8-liter V-10 because we didn’t think it lived up to that engine’s legacy -- until we put it on this hill.
The 6.2-liter V-8 ran up the hill a full 5 seconds and almost 5 mph faster than its next closest competitor, the Silverado. Its rpm seemed to pick up faster than the Hemi’s or the Vortec’s, and it was so fast that it shifted into second gear during one run, though it lost about 1,000 rpm and immediately downshifted. During the other sprints, the F-250 remained exclusively in first gear to top of the hill approaching near redline. The whole run the F-250 howled like a muscle car, not a three-quarter-ton truck with a combined weight of more than 17,000 pounds.
The Chevy 6.0-liter Vortec V-8 edged out the Hemi-powered Ram for second place up the hill by just 0.68 seconds, proving that shifting finesse and a wider range of gears can make up for moderate power deficiencies when a truck is being worked hard. It remained in first gear all the way to the top, crossing the finish marker at over 4,500 rpm and almost 25 mph.
The Ram 2500 always started out faster than the Silverado truck up the hill but couldn’t keep the power coming as steadily to the top. It wanted to, but the transmission seemed to hold it back. We can’t wait for this truck to get a future version of ZF’s eight-speed automatic. Still, after all of the grades, we remained very impressed by the Hemi’s overall performance at Milan Dragway and on the 7-percent and 16-percent climbs.
Three-Quarter-Ton Diesel Trucks Towing 10,000-pound Trailer
Hill-hold assist was one of our favorite features starting out on this grade. The GM and Ford trucks held their ground during the split-second pedal swap, thanks to the hill-hold assist feature. The Ram, which lacked the assist, started to roll back immediately even though we quickly moved from the brake to the accelerator.
Halfway up the hill, the Chevy 2500’s traction control briefly kicked in to squelch some instability caused by the grade’s rough surface and quickly butted out after the skipping was under control.
The Ford F-250 had difficulty with its traction control system, which kicked in to simmer down rear axle tramp at the start of the run.
While the F-250’s rear end hopped, the Ram 2500’s backside squealed, as its tires couldn’t hold traction on the takeoff. We had to feather the accelerator very carefully to avoid losing grip entirely. There was no stability control to cut fuel or apply the ABS for assistance. Because of this, the Ram 2500 finished about 5 seconds behind the Chevy Silverado 2500 and 4.1 seconds behind the Ford F-250.
Compared with the Ford, the Chevy’s traction control system was much less intrusive and seemed to do a better job helping the truck stay planted on the asphalt.
One-Ton Diesel Trucks Towing 12,000-Pound Trailer
Right off the line, the Ford F-350 dually spun its back tires and bounced each start up the grade. When this happened, the traction control system intervened and cut fuel to the engine to try to regain traction -- the F-350 SRW manages traction via defueling plus antilock brake application -- which caused the truck to lose turbo boost. Time and speed was lost over the first 200 feet as we tried to exit this acceleration-wheel-hop-traction-control loop. For most of the way up the hill, the F-350 also shifted between first and second as it struggled to find the optimal gear ratio for the climb, finally settling into second just before the top.
The Sierra 3500 doesn’t have traction control, so we didn’t lose turbo boost, plus its new rear suspension and wider, asymmetrical leaf springs did a fair job keeping the truck planted. It was a half-second faster than the Ford and 6 seconds quicker than the Ram.
Even though the Ram 3500 wasn’t fast, it had relatively smooth launches despite that fact that it also lacked traction control. They were better than the three-quarter-ton Ram 2500’s starts and suffered less wheel hop than the Ford and GMC. The one-ton Ram rolled back a few inches at the start, but once it found traction it chugged up the hill and made it to second gear by the crest, though it seemed to lose power in the midrange, around 2,500 rpm.
The Ram 3500 did cause some concern for us after our final test run, when its transmission temperature spiked from 212 degrees to 255 degrees, almost 60 degrees higher than the Ford and GMC pickups.