Cummins Inc. showcased the results of a four-year joint program with the U.S. Department of Energy (DOE) at the recent Mid-America Trucking Show in Louisville, Ky. The Advanced Technology Light Automotive Systems (ATLAS) program was initiated to develop a commercially viable diesel engine for the half-ton pickup truck market that is capable of meeting future Tier 2 Bin 2 emissions regulations and Corporate Average Fuel Economy (CAFE) and stringent greenhouse gas (GHG) requirements out to the year 2025.
The demonstration vehicle, provided by Nissan North America, is a 2010 Nissan Titan originally equipped with a gasoline V8 engine. In addition to meeting fuel-economy and emissions requirements, the new engine needed to accomplish the same work as the large gas V8, so maintaining a torque output of 385 ft/lbs was necessary. The Cummins team chose a 4-cylinder ISF2.8 base engine to begin research, and from there, the evolution began.
"When we launched ATLAS, the team understood that they had to think outside the box to achieve our targets," said Michael Ruth, director/technical project leader, advanced light duty. "Specifically, we knew that weight reduction, advanced emissions control technologies, advanced thermal management and powertrain integration would be critical to meeting all of the requirements. The challenge was making those significant advancements while ensuring that the engine we produced would be commercially viable."
The end result after the four-year effort was a 362-lb, 2.8L engine with an aluminum block, head and oil pan, a magnesium valve cover and an engine-mounted emissions control system. The ATLAS engine, including the on-engine aftertreatment system, weighs in at approximately 80 lbs lighter than the original all-aluminum gasoline V8.
The Highway Fuel Economy Test (HFET) and FTP-75 Test (city) cycles demonstrated fuel economy over 35 mpg and 25.5 mpg, respectively. This is approximately a 53 percent increase in CAFE fuel economy at 28.9 mpg, as compared with the production gasoline V8 fuel economy of 18.9 mpg. The Cummins team not only surpassed all fuel-economy targets, but also achieved criteria emissions lower than the stringent Tier 2 Bin 2 GHG levels.
The ATLAS engine uses advanced technologies to meet the future regulations. One of the most notable features is the aluminum block. While not visible from outward appearances, the engine is a through-bolt design with a structural cradle above the oil pan and another above the cylinder head, "sandwiching" the block and head and enabling very high cylinder pressure capabilities.
A "dual loop" Exhaust Gas Recirculation (EGR) system with both low- and high-pressure circuits and switchable valve timing improve light load emissions output and allow for increased power density of the engine. The overhead camshaft is driven by belt-in-oil technology. This lubricated belt system is designed to last the life of the engine. The ATLAS engine also uses ceramic glow plugs, a High Pressure Common Rail (HPCR) piezo-style fuel system complete with a Bosch high-pressure pump and a VGT Turbocharger. The complete package is controlled by Cummins controls technology.
Another unique feature is the engine-mounted aftertreatment. In partnership with Johnson Matthey, an on-engine catalyst was developed that has Selective Catalytic Reduction (SCR) wash-coat technology applied directly to the particulate filter.
In addition to the state-of-the-art diesel technology, an 8-speed ZF 8HP70 kept the engine operating at an optimum speed, helping to achieve a more than 50 percent fuel-economy improvement over that of the gasoline V8. The remainder of the truck's original running gear was unchanged.
Although the ATLAS engine is a research project, it was subject to all of the design standards and rigorous testing that Cummins performs on all products to ensure that the customer is receiving the most dependable and durable diesel engine available. On-road testing, towing, cold weather and chassis dyno testing, to verify that the ATLAS 2.8L met the U.S. emissions standards it was being measured against, resulted in a successful proof of concept. SAE International recognized the ATLAS team with the John Johnson Outstanding Research in Diesel Engines Award for their work, as published in the SAE paper Thermodynamic Systems for Tier 2 Bin 2 Diesel Engines (papers.sae.org/2013-01-0282).
