Words by Mike Levine, Mark Williams and Kent Sundling, Photos by Ian Merritt
Our second major climb was the eastbound ascent from Dillon, Colo., to the top of Eisenhower Pass on Interstate 70, the highest point in the U.S. interstate system. The grade starts at approximately 5 percent for two miles and then increases to about 7 percent for the remaining six miles, to the entrance of the Eisenhower Tunnel — the highest vehicular tunnel in the U.S. It’s perhaps the toughest stretch of road a loaded truck will encounter on a major cross-country highway; we call it the Nürburgring of pickup trucks because nearly every bit of towing and braking hardware is stressed to the max for many miles at a very high altitude.
We started at 8,776 feet in Dillon and finished at 11,000 feet above sea level, climbing 2,224 feet over nearly eight miles and 7,500 feet higher than the finish on Davis Dam Grade.
We drove each truck up the grade in tow/haul mode and two-wheel drive. Runs during which the driver let off the accelerator, braked or both were not counted. The fastest time was used for our comparison. We ran each truck up the grade in sequence, two times total. Each run included five adult males inside, adding another 1,000 pounds to the trucks. The trucks were at a dead stop before each run. The driver ran wide open throttle from start to finish. We didn’t encounter any traffic on the road during the late-night climbs.
Topographical map of Eisenhower Pass based on GPS data collected by our VBOX and exported to Google Earth. The red line representing our timed course up I-70 starts near the upper right, in Dillon, Colo., and finishes 40,000 feet (7.6 miles) later in the lower left, near the entrance to the Eisenhower Tunnels at 11,000 feet above sea level.
Temperatures at the start of the runs in Dillon ranged between 54 degrees and 62 degrees, according to the trucks’ outdoor temperature readouts.
Like the Chevy Silverado 3500 that won the Rumble in the Rockies test, the Duramax-powered GMC Sierra 3500 was the fastest truck up Eisenhower Pass. It finished in 8 minutes, 46.8 seconds – 84 seconds ahead of the F-350 and 152.6 seconds ahead of the Ram 3500. The Sierra’s average speed cruising up to 11,000 feet was 51.70 mph, 7.2 mph faster on average than the Ford and 11.35 mph faster on average than the Ram. The GMC’s top speed was 68.77 mph for a few seconds before the grade changed from 5 percent to 7 percent.
The Ford F-350's best time up the grade was 10 minutes, 16.6 seconds, at an average speed of 44.51 mph. The top speed was 58.5 mph, and it happened just before the point where the grade increased from 5 percent to 7 percent.
Some may notice that the Ford was much closer to the GMC in performance this time around compared to the Rumble in the Rockies. We noticed that improvement, too, even before we looked at the numbers.
This chart shows each truck's speed climbing Eisenhower Pass against the clock at wide open throttle. The GMC Sierra 3500's fastest run was 526.8 seconds, the Ford F-350's best time was 611.1 seconds and the Ram's quickest climb was 679.4 seconds. The sloped lines represent each truck's position climbing the mountain.
This chart shows the speeds of the three trucks relative to each other over the 40,000 foot (7.6 mile) run to the top of Eisenhower Pass. Note how similar the speed patterns are for each truck as the grade changes throughout the climb.
It seems as if Ford has improved the Power Stroke V-8 diesel’s performance at high altitudes. Last year, we tested a Ford F-450 and an F-350 in the Rocky Mountains, and neither truck was able to exceed 2,100 rpm at wide open throttle up I-70 when towing a heavy trailer. But in this test, we repeatedly saw the Ford hit and hold rpm levels as high as 2,700 rpm – just below its peak horsepower, which is critical for pulling with confidence and strength over long distances. And, in general, driving through the Rockies, without instrumentation running, there were times the Ford Super Duty could pull away (slowly) from the Sierra while climbing grades. If we assigned a ratio to our impressions, the Ford outpowered the GMC about 25 percent of the time in the Rockies while towing.
How was this F-350 able to dig deeper than the other 2011 Super Dutys we’ve driven? We suspect that Ford has continued to refine the Job 2 engine and transmission calibrations (Job 3?) to improve high-altitude performance. We have asked Ford for a comment, but we haven’t received a response as of this writing. We stopped at a Ford dealer in Denver to identify the firmware version, but the service computer only said the firmware did not require an update.
We don’t think Ford submitted a “ringer” for this test. If there’s a firmware update for this truck, you could take your 2011 Super Duty in for service and have it flashed to the same version as this truck. Wherever the change comes from, it’s welcome.