Once upon a time, when working trucks were rude and crude and completely task-focused, all truck engine engineers had to worry about was making sufficient torque, hauling power, and anvil-tough durability. Then came ever-toughening emissions and fuel-economy requirements, followed by increasing demand for refinement as Americans traded cars for pickups and SUVs, for transportation and weekend recreation.
So the lives of those engineers keep getting more challenging. The competitive pressures for power and torque on one hand and luxury, comfort and quiet on the other remain intense, while fast-accelerating emissions and economy requirements must be satisfied.
To understand the technology directions being taken by today's truck engine engineers to meet these oft-competing demands, let's look first at two very different 6.2-liter gas V-8s.
General Motors' 6.2-liter V-8 is the largest Gen IV small-block engine found in 2010 GM light-duty pickups and SUVs. A compact cam-in-block (CIB) V-8 (with its valves driven by pushrods riding roller lifters on a single camshaft buried deep in the block), it boasts a lightweight aluminum block and new-for-2010 variable valve timing (VVT), which GM calls cam phasing. With a fairly high compression ratio of 10.5:1, it generates 403 horses, 417 pound-feet of torque, and EPA economy ratings of 13 mpg city and 19 highway in 2WD pickups.
The versions used in GMC Yukon and Cadillac Escalade SUVs also have Active Fuel Management (AFM), GM's version of cylinder deactivation, which shuts down half the cylinders (by disabling lifters) to save fuel during light-load operation. And GM recently announced an $890 million investment to build its next-generation small-block V-8s, all of which will use an "all-new advanced combustion system design," plus aluminum blocks, cam phasing, VVT and the U.S. truck market's first application of high-pressure gasoline direct injection (DI).