2011 Ford F-250 Super Duty Lariat

The new turbocharged and intercooled 6.7-liter Power Stroke diesel V-8. Not only does it generate output ratings that make competing oil burners look tame—390 hp and 735 lb-ft—but it also produces these numbers at very low revs (2800 and 1600 rpm, respectively). Moreover, it represents a clean-sheet—or, more accurately, a blank-computer-screen—design by Ford, and it can burn B20 biodiesel. After a long and sometimes rancorous relationship with Navistar, Ford’s previous diesel-engine partner, the automaker elected to develop the next generation of its Power Stroke diesel in-house. Bosch worked with the Ford team to develop the turbo system, which entails an innovative variable turbo: one turbine wheel (supplied by Honeywell) with vanes on both sides, operating sequentially. Another intriguing design element is the absence of external exhaust headers. Airflow through the heads is reversed, with air entering on the outside and the exhaust ports and turbocharger inside the engine’s V. This allows for shorter plumbing and improves turbo response time and cooling. Like other contemporary common-rail diesels, injection pressures are enormous—close to 30,000 psi—to enhance fuel atomization and promote more-complete combustion. Even so, reducing oxides of nitrogen and particulates to meet emissions regs for all 50 states requires a significant 30 to 50 percent of the exhaust gases to be recirculated, plus urea injection upstream from the catalytic converter and a particulate filter at its exit. In addition to several other inventive elements, Ford claims its new engine weighs 160 fewer pounds than the Navistar 6.4-liter V-8 it replaces, thanks to aluminum cylinder heads and the use of a compacted-graphite-iron block. The ride does in fact seem velvety—on smooth pavement. But the first significant bump reminds you that there are substantial masses of unsprung weight moving around down there. This is, after all, a big truck; no one is going to confuse it with a Mustang. Similarly, the steering, designed to deal with immense loads, is slow and not at all tactile. The effort is about right, but on-center feel is simply not a part of the deal.