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

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Auto Tech: Ford’s SuperDuty diesel

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By Jim Kerr

When it comes to pulling power, truckers know that diesel is king. So when a new diesel engine comes along, they check it out carefully. Ford’s new 2001 SuperDuty diesel is definitely worth checking out.

This 6.7-litre Power Stroke V8 turbocharged diesel engine shares one thing with the previous Ford SuperDuty diesels: the Power Stroke name. Everything else is new. Past Power Stroke diesels were based on a design introduced by International. With this new engine, it is all Ford and the engineers started with a clean slate.

The most obvious change is to the exhaust and intake manifolds. This 6.7-litre engine has the exhaust ports facing the valley area of the engine between the cylinder heads. The short exhaust ports now feed directly into the turbocharger, which is located between the cylinder heads. From the turbocharger, the exhaust gases exit through a single large pipe down the back of the engine and into the converters and muffler. This is a very simple and compact exhaust arrangement and has advantages in performance by providing quicker turbocharger boost and in easier serviceability because of simpler exhaust routing.

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

Although not a part of the engine, the exhaust system beneath the truck requires mention. This new system looks like a rocket booster and is part of the emissions system that most diesel engines require to meet the 2010 emission standards. It consists of several parts, including a particulate filter to trap carbon particles and a couple of converters to break down the exhaust gases. One of the converters uses Diesel Exhaust Fluid (DEF) to help break down the gases. This DEF, also called Ad Blue by Mercedes, is a liquid Urea solution and is stored in a separate tank beneath the truck box. The fluid is injected into the converter as needed to help convert the exhaust. The amount of DEF injected will depend on driving conditions, but a tank-full will normally last for one regular service interval.

Back to the engine, the turbocharger pulls in clean air from the air filter, compresses it, pushes it through the intercooler and then back through passages cast into the valve covers and down through the top of the cylinder heads. This unusual arrangement of air flow again simplifies the engine compartment, making service parts more accessible. The turbocharger itself is a twin compressor design in a single unit. Two compressor wheels are connected to a common shaft and both are driven at the same speed by the exhaust gases. The compressor wheels are shaped and sized differently and work progressively to provide boost over a wide range. This shows in the truck’s pulling power. With 735 foot-pounds of torque at 1,600 r.p.m., this engine is strong. I experienced its pulling power up a six-degree slope with a 42-foot trailer loaded to maximum towing capacity and the truck didn’t even hesitate. It accelerated up to speed and maintained it, even shifting into high gear at times on the slope.

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

The fuel system is a direct-injection Bosch design. Ram and GM trucks also use Bosch components, and this new Ford system uses a common rail design with fuel pressures that can go up to 29,000 psi. The injectors will fire several times for each power stroke, which may include a couple injection pulses as the piston is rising on the compression stroke and a few injection pulses as the firing cycle continues. Pre-injection helps reduce the “diesel knock” noise we are familiar with, while post injection keeps the cylinder pressures higher for more power. The system is also designed to operate on B20 Biodiesel if you desire.

While designing the engine, ease of service was kept in mind so maintenance costs are lower. The oil filter is easily accessible and even the oil drain plug is a quarter turn-type device. Fuel lines for the common rail system are located on top and the injectors can be removed without major engine disassembly. Even ancillary parts, such as the water-cooled exhaust gas recirculation system, is clear and free of other devices for ease of service.

The new SuperDuty diesel has no shortage of power, gets great fuel economy (I got 9.4 L/100 km!) and is designed for quick maintenance. Some may be leery of a new engine design, but thousands of hours of testing at maximum loads helped engineers find weaknesses and correct them before the engine went into production. The 2011 SuperDuty diesel really is a super engine.

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