2011 Ford F-series Super Duty turbodiesel
2011 Ford F-series Super Duty turbodiesel. Click image to enlarge

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By Jim Kerr; photos courtesy Ford

Ford’s 2011 SuperDuty trucks will soon be at the dealerships and powering them will be new gas and diesel engines. Both are completely new designs with increased power and better fuel economy. While the gas engine is powerful, the new 6.7-litre diesel engine is amazing: with 735 foot pounds of torque, the diesel will practically pull the truck’s maximum towing capacity of 11,068 kg (24,400 lbs) as if it wasn’t even there!

To perform this, the Ford engineers started with a clean slate to build the first Ford-designed SuperDuty diesel engine (previous engines were based on International Truck designs). The first noticeable change is the head design: the exhaust ports are located on the inside of the engine valley and feed through a short passage directly to the new turbocharger. After passing through the turbocharger, the exhaust gases flow through a single large exhaust pipe down the back of the engine to the converters and muffler. This design eliminates the snake pit of piping associated with getting the exhaust on a V8 engine back to a centrally mounted turbocharger and out the tailpipe. The simple design of the new system means reduced labour costs for any service work, which is good news for long-term owners.

2011 Ford F-series Super Duty turbodiesel
2011 Ford F-series Super Duty turbodiesel. Click image to enlarge

The turbocharger is also new. Built by Honeywell, the computer-controlled variable vane design spins a single exhaust turbine wheel, which drives a single shaft with two compressor wheels on it. Both compressor wheels provide boost but do it in stages because of the different sizing of the wheels and scrolls surrounding them. This single-sequential turbocharger provides much of the advantage of a twin turbo system in a much more compact package.

Instead of feeding air into the side of the cylinder head, this new design directs air through passages in the valve cover and down through the top of the cylinder head. The design is again compact and provides great airflow. The four-valve cylinder head has narrow individual rocker arms for each valve constructed so they can sit closely side by side; each roller lifter contains two small hydraulic adjusters that move two pushrods so each valve is automatically adjusted individually.

2011 Ford F-series Super Duty turbodiesel
2011 Ford F-series Super Duty turbodiesel. Click image to enlarge

Fuel injectors are mounted through the valve covers and steel lines connect the common fuel rails to each injector, a design that leaves the injectors accessible for quick service if necessary. It would only take a few minutes to remove an injector, lowering vehicle maintenance costs. Fuel pressure in the Bosch common rail system is supplied by a mechanical pump easily accessed at the front of the engine and fuel pressure peaks at 30,000 PSI, which ensures instant atomization for maximum power and efficiency. The computer can fire each of the electronic fuel injectors up to five times per combustion cycle and uses two pilot injection pulses at idle to keep engine noise low. Driving the truck, I found it so quiet that it was easy to forget there was a diesel under the hood. Only full throttle acceleration at low speeds allows some diesel noise into the cab.

Fuel economy was one of the engine designers’ priorities. Better airflow, less internal friction, aluminum components to reduce weight and attention to combustion chamber design all combine to provide surprising economy. I observed 30 miles per gallon (9.4 L/100 km) over a hundred miles of gravel, dirt and paved roads at speeds between 75 and 100 km/h with four passengers and a 1,000 pound cargo load!

2011 Ford F-series Super Duty turbodiesel
2011 Ford F-series Super Duty turbodiesel. Click image to enlarge

Serviceability appears to be incorporated into every aspect of this new engine. The top end of the engine is open and easy to access components. The oil filter has been located down low near the back of the engine for quick, clean service and the new oil drain plug is a special quarter-turn design. No more over-tightened drain plugs or stripped threads.

Durability was another key goal in this new engine design. Only time will prove it, but Ford has tested every component and operated the engine for hundreds of hours continuously at full load to test durability and ensure they meet their goal of 250,000 miles/400,000 kms without major component failure.

Ford’s SuperDuty diesel engine is setting new standards for power, refinement and economy. The only drawback is it is so quiet, you might accidentally want to fill the tank with gas instead of diesel.

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