Until now, Ford has equipped its trucks with Navistar diesel engines. Overall, Navistar products have been reliable, and provided sufficient power, but warranty issues created disputes between the two manufacturers, and became serious enough that a negotiated settlement was required.
It's not surprising that Ford turned to its own staff to develop an engine for the next generation Super Duty truck, even though engineers were faced with a number of challenges in its design.
- The engine had to produce enough power to satisfy Super Duty owners
- Decent fuel economy was a priority
- The ability to burn biodiesel would be a plus
- Long term reliability was a critical requirement
- The engine had to meet stringent emission standards
Unique Single-Sequential TurbochargerFord's end result is a 6.7-liter Power Stroke diesel with an industry first, single-sequential turbocharger that combines the benefits of twin turbochargers into a single unit. The result is fewer moving parts, less vibration and an elimination of some of the sounds of air movement typically associated with twin turbos.
In a typical turbo charged system, the exhaust manifolds are mounted on the outside of the cylinder heads, and the turbo is usually mounted behind the engine. That type of set-up uses piping to route the exhaust from the manifolds to the turbo, where it spins the impeller.
In Ford's system, the exhaust manifolds are located between the cylinder heads, where they connect together and run directly to the turbocharger, which is mounted at the top rear of the engine. Exhaust travels a much shorter distance, creating a better airflow through the turbocharger and increasing power.
With exhaust manifolds located between the cylinder heads, there's less surface area to radiate heat, keeping excessive heat from affecting other components under the hood.
Multi-Firing Fuel Injection SystemA normal diesel engine fires a single spray of fuel into each cylinder. Ford's multi-firing fuel injection system fires up to five sprays, depending on power needs, resulting in more power, easier starting in cold temps and a reduction of engine noise. The new engine has a three-part system that helps reduce exhaust emissions:
- A diesel oxidation catalyst converts hydrocarbons into water and carbon dioxide, and raises exhaust gas temperature to help other parts of the system work more efficiently.
- Selective Catalytic Reduction (SCR) helps convert nitrous oxide (NOx) in exhaust to water and nitrogen; diesel exhaust fluid mixes with exhaust to help the chemical reaction inside the SCR module.
- A Diesel Particulte Filter (DPF) traps remaining soot, which is burned away when sensors detect that the trap is full.
The engine block and heads are made from lighter weight materials, but are designed for strength in critical areas that are under stress and pressure (like the lower engine block and cylinder head combustion area).
Ford engineers tested the engine under a variety of conditions on a dynamometer before performing actual on-road testing (the equivalent of 250,000 miles). Their goal was to produce an engine that's both strong and reliable -- and not let customers be the ones to find its weaknesses.
Ford has not released horsepower or torque specs yet, but says both will be higher than the current engine's. Ford also promises increased towing abilities and a higher payload capacity, but with better fuel economy and the option of running up to a 20-percent biodiesel/petroleum diesel mixture. In addition, engineers were able to improve -in-cab sound levels by lowering the noises normally associated with diesels.
Time will tell how Ford's new diesel engine performs and holds up, but the automaker is definitely trying its best to insure a trouble-free roll-out.