Testing the Three Most Powerful Pickups Ever Made
In our first “King of the Hill” article (Feb. ’11), we teamed up with Mike Levine of PickupTrucks.com and headed to Denver, Colorado, with an ’11 Ford F-350 and an ’11 Chevy Silverado 3500. Ford’s 400hp version of the 6.7L Power Stroke powered the Super Duty and the Silverado was fitted with GM’s retooled ’11 397hp 6.6L Duramax.

We drove the trucks from Detroit to Denver and gathered fuel economy data on the two four-door dualies. When we got to the base of the Rockies, we loaded up a tandem-axle, dual-wheel trailer with 18,900 pounds and headed over the top of the Continental Divide to see which truck had the most power.

With our resident truck engineer Harry Rawlins at the wheel and Mike Levine collecting data at a rate of 10 times per second, we staged each truck on our 8,800-foot elevation starting line at the Dillon Colorado onramp for I-70 East. From a standstill, Rawlins floored the throttle and held it there till the truck crested the top of the grade at nearly 11,000 feet.

Round 1: Duramax Beat Power Stroke
That Ford vs. Chevy test was enlightening to say the least. Although the two trucks were rated with similar power, the Duramax put more power to the ground at high elevations. The Silverado ended up trouncing the F-350 by more than 2 minutes during our 8-mile climb.

Our staff speculated about how the Chevy outran the Ford. Was it the turbo? The engine calibration? Or something else GM had mastered during 10 years of building the Duramax? We decided either the Power Stroke’s dual-compressor turbo wasn’t spinning fast enough (to move the air the engine needed at altitude), or GM’s Duramax was in fact making more power than the claimed 397 hp. In truth, both theories were somewhat correct.

But Something Was Missing…
While we were consumed with figuring out why the Duramax outran the Ford, our readers seemed more interested in knowing how a 6.7L Cummins-powered Ram would do in the same test. For six months, all we could say was, “The Ram isn’t rated to tow 18,900 pounds.” But then, this spring, Chrysler announced it would release a high-output (800 lb-ft) version of its heavy-duty truck, and that version would be available with a new trailering package that increased the Ram’s pulling capacity to up to 30,000 pounds. That was great news for Cummins fans, and it also meant we’d have to hold a King of the Hill rematch.

Cummins’ 800-Lb-Ft Combatant: Ram 3500
Beginning with the mid-’11 models, the Ram 2500 and 3500 are now available with a high-output 800-lb-ft 6.7L Cummins. The new engine calibration still offers 350 hp, but the Cummins’ mighty torque curve is allowed to come out and play a little more. Also new for Ram is a Max Tow package that elevates the towing capacity of a four-door, four-wheel-drive 3500 to 29,000 pounds.

The new high-output package takes the added torque from the Cummins, couples it with a new converter, and sends it through a 68RFE transmission that now benefits from an ATF-to-water transmission fluid cooler. The Max Tow package then ups the ante with a rear axle that’s fitted with 4.10 gears to give the Ram the strongest off-the-line launch in the industry. We suspect the 4.10s were also chosen to reduce the stress on the transmission.

Other Max Tow upgrades include a stronger AAM 1150 rear axle updated with larger bearings and a stronger limited-slip differential—and there’s even a new cast-aluminum differential cover that’s said to reduce gear lube temperatures by 20 to 30 degrees. The Max Tow package also fits the truck with a larger power-steering cooler.

Cummins fans are no doubt nodding their heads as they read this, saying: “That’s the stuff we’ve been adding to our trucks for years—and towing way more than 20,000 pounds.” And in many cases, they’re absolutely right. Keep reading to see how the new Ram stacks up against the diesels from Ford and GM.

Looking For a Rematch: Ford F-350
General Motors supplied both the Ford and Chevy in our first King of the Hill shootout. While we stand behind the results of the first comparison 100 percent, some readers feared GM might have given us a ringer of a Chevy and a dog of a Ford for the test. As much as we tried to dispel these concerns, we knew we’d never be able to make everybody happy till we held a rematch. And this time we’d be sure to get an F-350 straight from Ford Motor Company in Dearborn, Michigan.

On paper, the F-350 in this test should have the exact same performance as the last one we tested in Denver. Its 6.7L Power Stroke is still rated with the most horsepower in its class (400 hp) and the same torque as the new Ram (800 lb-ft). Officially, there have been no changes to the 6.7L Power Stroke, but according to our aftermarket sources, there are nearly 24 calibrations for the 6.7L. It seems Ford is fine-tuning its new diesel, and every ’11 Super Duty we’ve driven seems to run better than the last. The F-350 you see on these pages is the strongest one we’ve tested to date.

Reigning Champion: GMC Sierra 3500
Of the Big Three, General Motors’ diesel program has come the farthest in the last decade. Twelve years after Dodge brought us the 5.9L Cummins and six years after Ford debuted the 7.3L Power Stroke, GM finally built a diesel engine enthusiasts could be proud of. When launched, the 6.6L Duramax joint venture between GM Powertrain and Isuzu resulted in a product unlike anything pickup truck buyers had ever seen. The aluminum-headed V-8 offered 50 hp more than the automatic transmission-equipped 7.3L Power Stroke and 65 hp more than the automatic-equipped Dodge. Though the torque numbers were closer to 505 lb-ft for the Power Stroke trucks with the automatic (525 lb-ft for the manual-transmission version) and 460 lb-ft for the 5.9L Cummins (505 lb-ft for the manual-transmission version). Since day one, the Duramax has clearly been a horsepower engine and—10 years later—it still is.

For those of you paying attention, the Duramax-powered truck in our test is technically an early ’12 GMC Sierra 3500. We’ve been told it represents the same powertrain performance as the current ’11 model-year Duramax-Allison combination, though there have been some tweaks to its emissions monitoring systems. In essence, this truck should make the same power as the Chevy Silverado 3500 we tested in “King of the Hill” (Feb. ’11) and the GMC Sierra 2500 we tested in “2011 Diesel Truck of the Year” (July ’11).

19,400-Pound Measuring Stick
There are a number of ways to test the power output of a pickup truck. As Diesel Power readers, you’ve seen us chassis-dyno vehicles, race trucks on the dragstrip, and even tow trailers down the dragstrip. But when we teamed with PickupTrucks.com last year, we brought you a new test of power to the equation—and this one is as real world as it gets.

Rather than simulate a load on a dyno or calculate a truck’s horsepower potential on a dragstrip, Titan Trailers in Waterville, Kansas, lent us three of its 30-foot-long Ruff Neck tandem-axle, dual-wheel, dovetail gooseneck trailers that each weighed 7,000 pounds. Then we hauled all three trailers to Pioneer Sand in Northglenn, Colorado, where we added an additional 12,000 pounds of stone to each one. When we rolled out of the landscape supply yard, each truck was grossing nearly 29,000 pounds, and each driver would require a Class A commercial driver’s license.

There are dynos in the United States that are likely capable of simulating towing a 19,400-pound trailer—but nobody drives a dyno. So what better test could there be than hitching up to a serious load and heading out to tackle the steepest and toughest tows we could find?

Truck Specifications

Make / Model 2012 GMC Sierra3500HD DRW 2011 Ford F-350 DRW 20111/2 Ram 3500 DRW Configuration


Cab Type Crew Cab Crew Cab Crew Cab Trim SLE XLT SLT Big Horn Color Fire Red Dark Blue Pearl Metallic Mineral Gray Metallic Powertrain


Engine 6.6L V-8 6.7L V-8 6.7L I-6 Horsepower 397 hp at 3,000 rpm 400 hp at 2,800 rpm 350 hp at 3,000 rpm Torque 765 lb-ft at 1,600 rpm 800 lb-ft at 1,600 rpm 800 lb-ft at 1,500 rpm Compression Ratio 16.0:1 16.2:1 17.3:1 Transmission Allison 1000 six-speed auto 6R140 TorqShift six-speed auto 68RFE Orion six-speed auto Rear Axle Ratio 3.73 3.73 4.10 First 3.10 3.97 3.23 Second 1.81 2.32 1.84 Third 1.41 1.52 1.41 Fourth 1.00 1.15 1.00 Fifth 0.71 0.86 0.82 Sixth 0.61 0.67 0.63 Tires LTX M/S LT235/80R17 Michelin LT245/75R17 General Grabber TR LT235/80R17 General Ameritrac Capacities and Weights


Fuel Capacity 36 gallons 371/2 gallons 35 gallons GVWR 13,000 pounds 13,000 pounds 12,300 pounds GCWR 29,200 pounds 30,000 pounds 29,000 pounds Curb Weight 8,140 pounds 8,420 pounds 8,040 pounds Trailer Weight 19,400 pounds 19,400 pounds 19,400 pounds Gross Combined Weight Rating 94.3 percent 92.7 percent 94.6 percent Price as Tested


MSRP $55,710 with $995 destination $56,900 with $975 destination $58,200 with $975 destination

2,000-Mile Road Test
The first thing you need to know about these three trucks is this: They are all impressive when towing twice their own weight. Moving down the highway at 65 to 80 mph with nearly 30,000 pounds being hefted by each engine and transmission is like piloting your very own freight train. Each of the trucks completes this task admirably, and all three pickups will do this job well for their owners. There were, however, some differences that stood out immediately as we headed west on I-70.

The first time we put the 800-lb-ft Ram into gear, the extra torque felt obvious. We found ourselves checking to see if the transfer case was in low range. Yet when we got up to highway speeds, a few things became clear. The first was that even though the Ram matches the Ford (and beats the GMC) in torque production, towing this much weight at highway speeds is a test of horsepower—not torque. The Ram showed its 50hp deficiency attempting to keep up with the Power Stroke and Duramax everywhere we went. The other lesson we learned from the Ram was that putting 800 lb-ft through a transmission requires big internal components, or firm shifts, and it’s clear to us the 68RFE’s architecture has to work a lot harder and shift a lot harder to survive at these power levels and tow ratings compared to the Allison and TorqShift. With 19,400 pounds in tow, these trucks spent a lot of time at wide-open throttle—and that meant a lot of shifts in the Ram felt like the 68RFE was pushing the limit of its capabilities.

Acceleration and Brake Testing
Our first destination for the trucks was Chrysler’s Arizona Proving Grounds in Yucca. This 3,800-acre facility began life as the Yucca Army Airfield during World War II. Ford bought the land in 1954 and built more than 50 miles of private roads to conduct hot-weather testing—away from the public’s eye.

Every diesel pickup Ford’s ever built has been tested here. Chrysler purchased this place in 2007, and now it’s where the next-generation Rams will prove their worth.

We used the Proving Ground’s Vehicle Dynamics Area to test each truck’s acceleration with and without a trailer. The Super Duty, Sierra, and Ram were all fitted with a GPS-based, data acquisition system from Racelogic. The trucks were tested in both directions, and the speeds were averaged together to compensate for the wind.

As the afternoon sun burned on and we collected our data, our seat-of-the-pants hunch was proving correct. Though the new 800-lb-ft, high-output Cummins is a rocket ship off the line, it can’t keep up with the new Duramax and Power Stroke diesels.

Our tests show that with the trailers hooked up, there’s less than a second between all three machines—but the Ford is the quickest through the quarter-mile. But to show you how close the Ford and the GMC are, when we raced to 55 mph, the GMC was quicker than the Ford. Cummins fans can take some comfort in knowing that the Ram was quickest off the line, but the longer the race went, the further it fell behind the Ford and GMC.

Accelerating this much mass through the quarter-mile in less than 30 seconds is impressive, but bringing it to a stop quickly can mean the difference between life and death. To prove this point, we conducted a series of panic stops from 40 mph. The results showed that the Ford was clearly the best at slowing nearly 15 tons.

Some of you may also be interested to know how well the trucks would stop in the event of a trailer-brake failure. Though we’d never recommend towing without properly functioning trailer brakes, you can see from our test data what each truck is capable of in the worst-case scenario.

Acceleration Testing

With Trailer
Without Trailer
1/4-Mile Time 1/4-Mile Speed 0-55 mph
1/4-Mile Time 1/4-Mile Speed 0-60 mph Ford F-350 25.63 seconds 55.13 mph 26.21 seconds
17.56 seconds 83.03 mph 9.53 seconds GMC Sierra 3500 26.00 seconds 56.24 mph 24.41 seconds
17.22 seconds 84.97 mph 9.23 seconds Ram 3500 26.39 seconds 53.46 mph 28.41 seconds
17.81 seconds 81.63 mph 10.40 seconds *The times shown are the average of runs made in both directions of travel

40-0 mph Brake Testing with Trailer

With Trailer Brakes Without Trailer Brakes Braking Distance Increase Without Brakes Ford F-350 94 feet 143 feet 52.1 percent farther GMC Sierra 3500 114 feet 165 feet 44.7 percent farther Ram 3500 105 feet 164 feet 56.2 percent farther

Low-Altitude Desert HillClimb Results

Run 1: (Ambient Temperature at Start of Test: 101 F to 103 F) Run 2: (Ambient Temperature at Start of Test: 90 F to 94 F)
Time Time Ford F-350 11:58.9 minutes 11:50.8 minutes GMC Sierra 3500 12:15.4 minutes 11:11.3 minutes Ram 3500 13:20.2 minutes 12:54.2 minutes

SAE J2807 Towing Criteria
The automotive industry agrees on a number of standards that all manufacturers follow in order to build and sell comparable products to their consumers. There are guidelines for all kinds of things, but one standard that has never been agreed upon is how a vehicle’s tow rating capacity can be determined. At this point, that responsibility has been left to each vehicle manufacturer.

There’s currently a movement within the Society of Automotive Engineers (SAE) to standardize the process of determining how much a vehicle can tow, and that proposed set of criteria is called J2807. We introduced many of our readers to the rough-draft version of J2807 in “Society of Automotive Engineers International-Towing Capacities without the Marketing Hype” (Nov. ’09).

One of the proposed requirements for the SAE’s new standard is each vehicle must be tested on a set route that’s located north of Bullhead City, Arizona, on U.S. Highway 68. This nearly 12-mile run begins at around 600 feet above sea level and climbs a 5-percent grade. In the summer months, the outside temperature is almost always in the triple digits. So that’s where we headed to test the trucks to see how each could tow a trailer in the hot weather, and at a lower altitude.

We hooked each truck up to a 19,400-pound trailer and made two runs up the grade to Union Pass. Run 1 was made in the heat of the afternoon, when it was between 101 and 103 degrees out. Run 2 was made the following day, when it was 10 degrees cooler. Again, the results were close. The Ford had the advantage when it was hottest out. The GMC appeared to prefer cooler weather. The Ram pulled with all its might, but it was never really within striking distance of the other two trucks.

Rocky Mountain Torture Test Results

Run 1 (Temperature at Start of Test: 60 F to 62 F) Run 2 (Ambient Temperature at Start of Test: 54 F to 57 F)
Time Time Ford F-350 10:16.6 minutes 10:24.3 minutes GMC Sierra 3500 9:09.8 minutes 8:46.8 minutes Ram 3500 11:49.9 minutes 11:17.6 minutes

With the hot-weather testing completed, we headed back toward the Rockies with our three trucks and trailers for our high-altitude testing. The eight-mile climb from Dillon, Colorado, to the Eisenhower Tunnel is a 5- to 7-percent grade climb on the eastbound side of I-70 that begins at a staggering 8,800-foot elevation. From there, the winding interstate route curls up to an 11,000-foot pass. The temperatures in Colorado were 30 degrees cooler, but the air is so thin that it represents a whole new series of challenges for diesel truck engineers.

For this test, we loaded five guys into each truck and conducted our testing in the middle of the night. Each truck was staged in the same location and run up the climb at wide-open throttle towing the same 19,400-pound trailer. To set the bar, we ran the GMC up the grade first. Though the vehicle weighed almost 750 pounds more than the last Duramax-powered Chevy we tested here (due to the added weight on the trailer and the extra guy in the truck), the GMC still rocketed up the climb in less than nine minutes.

When it was time to test the F-350 (again, pulling approximately 750 pounds more than last time), the 6.7L Power Stroke was also faster than the last Ford we tested here. But it was still no match for the GMC.

But the truck everyone wanted to see make its first attempt at the Colorado climb was the new 800-lb-ft Ram. The 6.7L Cummins had a mighty launch coming up the highway onramp, but even before we pulled through the 11,000-foot-high finish line, it was evident to all of us in the truck that the Ram was out-gunned in this horsepower war.

The Winner Is
As we said in the beginning of this article, all three of these diesel trucks will tow an incredible amount of weight—and all of them will make their owners proud every time they hook up to a trailer. During our weeklong test, we literally covered thousands of miles and spent thousands of dollars to find out whether Ford, GMC, or Ram builds the most powerful diesel pickup on the planet. Though all of them are great trucks, it’s clear that the 6.6L Duramax-powered, Allison 1000-shifted, GMC Sierra 3500 put more power to the ground in more of our tests. So the reigning Diesel Power King of the Hill is still the champ.

Winner: ’12 GMC Sierra 3500.

Fuel Economy

Ford F-350 GMC Sierra 3500 Ram 3500 Total Distance Traveled Per Odometer 2,233.6 miles 2,193.0 miles 2,203.0 miles Total Fuel Consumed 241.9 gallons 247.4 gallons 270.9 gallons Total Amount Spent On Fuel $936.30 $958.46 $1,051.03 Fuel Economy 9.5 mpg 9.1 mpg 8.5 mpg

Want To See These Trucks on the Dyno?
Our two hillclimbs and quarter-mile drag races confirm that when it comes to towing a trailer with a dualie pickup, the GMC Sierra 3500 can out-gun the Ford F-350 and Ram 3500 nearly every time. But there’s more to the story…Check out DieselPowermag.com to see all three trucks makes pulls in Third, Fourth, and Fifth gear on a chassis dyno