Super-Efficient Ford

May 4, 2010 08:00 AM

Ford has finally done it. The 2011 Super Duty arrives at the farm gate this spring with an all-new Ford-engineered, -designed and -built diesel engine that gets more than 20 miles per gallon (mpg)—and it comes without a price increase for the diesel option.

Farmers are the biggest users and abusers of pickups. Throughout my years of farming, I've chronically overloaded every pickup. So when Farm Journal asked me to join other journalists in Arizona to test the 2011 Ford Super Duty models, I wanted to be sure these trucks would pay their way on the farm just like a tractor or combine.

Arizona's 7% grades provided a good place to tow, and we had plenty of opportunity to make the trucks grunt.

The first thing I noticed about this new line of Ford heavies is smooth acceleration all the way to redline. Smooth shifting, no turbo lag, no jerk from the new exhaust brake, less jerk from grade shifting—it's as close to a car feel as I've ever experienced in a heavy-duty truck.

Ford has long relied on Navistar to supply its diesel engines, but it broke that relationship because of quality issues and differences of opinion about diesel technology. The new homegrown 6.7-liter Power Stroke V-8 turbocharged diesel with 735 ft.-lb. of torque (at 1,600 rpm) and 390 hp (at 2,800 rpm) is B20-compatible. Your other heavy-duty option is a dual-spark-plug, 6.2-liter V-8 gasoline engine that delivers 405 ft.-lb. of torque (at 4,500 rpm) and 385 hp (at 5,500 rpm) with E85 compatibility. The 6.2-liter engine is an overhead-cam, large-bore/short-stroke design that delivers 90% capacity at 2,000 rpm.

Fuel mileage is the big news with this introduction. The outgoing 6.4-liter Power Stroke diesel was in last place in the miles-per-gallon race, but the 6.7-liter may prove to be the new leader with 18% mpg improvement (15% better on the gas model). After a drive of several hundred miles with a 1,000-lb. payload, the information screen displayed 20 mpg to 23 mpg readings.

The improvement comes by optimizing combustion and cooling in the new engine. The new diesel is reverse-flow, with an exhaust manifold in the valley below the dual-compressor-wheel turbo. There are two complete cooling systems and pumps on the diesel. Transmission, steering, intercooler and even engine cooling circulate through new separate radiators. It looks like a plumber's nightmare under the hood, but Ford claims that engine service is simpler, with less need to pull the cab for surgery.

The extra power allows higher axle ratios, similar to what semi trucks have done for better fuel mileage. The engine can even lug down to 900 rpm with the transmission torque converter still locked, thanks to a new damper.

Another part of the miles-per-gallon equation is that the torque converter will lock up sooner and stay locked up longer in tow mode, acting like a manual transmission. You can let the truck do the work in normal mode, shift yourself in manual mode or control what the highest gear will be
in progressive mode. In tow/haul mode, you can downshift by tapping on the brake as the revolutions per minute allow. The lower torque peak power of 1,600 rpm and double overdrive lets the diesel engine run slower.

Top towing. Ford again tops the towing field with the same trailer brake controller it introduced in 2005, but this time it can be adjusted in the dash display to work with electric-over-hydraulic trailer brakes and electric trailer brakes. For increased torque and horsepower on its single rear wheel (SRW) trucks, Ford added a larger ring and pinion in its Sterling rear differentials. The differentials feature E-Lock, which manually engages with the 4x4 switch. Dual rear wheel (DRW) drivetrains have larger U-joints.

The lower 3.97 first transmission gear offers great trailer launch ability and you won't miss the lower gears. The new automatic transmission can manually shift all six gears. Tow/haul mode holds engine revolutions per minute higher than usual before upshifting. This keeps the truck from getting bogged down when it's towing and it automatically downshifts the truck with a tap of the foot brake.

I drove an F-250 diesel Lariat Crew Cab 4x4 SRW with 3.55 rear axle. Towing 9,900 lb. up 7% grades didn't challenge this configuration, which has a max conventional trailer capacity of 14,000 lb. and max fifth-wheel capacity of 15,700 lb. I tested the Hill Start Assist feature, and it held the truck for a couple seconds.

I took an F-450 pickup with 4.30 axle ratio up the same hill with a triple-axle, 24,000-lb. gooseneck. I had great control on the way down with the automatic exhaust brake in tow mode, grade shifting and locking the highest gear to third with progressive shift mode. Turning tight corners, though, made the M80 Dana True Trac differential shudder.

Got gas? Ford uses the same low-first-gear transmission in gas as with diesel. As in the diesel, you'll find a nice spread of gears instead of just a double overdrive for improved fuel mileage. The Super Duty with the 6.2-liter gas engine can actually use all six gears.

The only axle ratio for the SRW is the 3.73, which is not the ratio we're used to for towing 10,000-lb. trailers. Towing a 9,900-lb. conventional trailer, the 6.2-liter howled near redline at 6,000 rpm. Without a trailer, it has a nice low-torque throttle sound, but under load the engine is louder in the cab than the diesel engine.

Using the progressive shift option on the all-new six-speed 6R140 automatic in tow mode allowed me to manage which gear holds the best revolutions per minute for proper torque range on the gas engine. It wasn't easy to evaluate a gas engine after driving a diesel, though. The 6.2-liter feels stronger than the 5.4-liter gas engine it replaces, with some of the improvement credited to the new six-speed automatic transmission gear spacing. 

The 6.2-liter throttle response is good with a trailer, but you know it's not the 6.8-liter V-10 gas engine, which is still available with DRW cab and chassis but only with last year's five-speed 5R110 automatic transmission.

The only other choice with a gas engine is to go with the 4.30 axle ratio, available only with 22,000-lb. gross combined weight rating for an SRW or DRW. All Super Dutys have Dana front axles and have inherited the independent trailer braking to control sway from the F150, along with electronic stability to control an empty truck on slick roads.

Service calls. The 2-qt. oil filter is less of a mess than the cartridge 1-qt. filter Ford has used since 2003. The new diesel exhaust fluid (urea) for the lower federal emission standard NOx rating is filled next to the diesel cap in the bigger fuel door. To drain the engine oil, just slip a ratchet over the plug and make a quarter turn to drain.

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