CGI block, longer B50 life highlight upgrades to new International MaxxForce 7
October 1, 2010
DENVER, Col. - With Navistar International declaring it will be vigorously pursuing medium-duty market share, the performance of its new MaxxForce 7 engine will have much influence on whether the comp...
DENVER, Col. –With Navistar International declaring it will be vigorously pursuing medium-duty market share, the performance of its new MaxxForce 7 engine will have much influence on whether the company achieves its goal of capturing half the total Canada/ US market.
Navistar senior vice-president of North American sales operations, Jim Hebe, promised the truck and engine manufacturer would achieve 50% market share during a series of dealer training sessions held across the US and Canada in recent weeks. A portion of the 2010 Assault on Medium-Duty Boot Camp training sessions were dedicated to educating International sales reps on the new MaxxForce 7, which will power most International TerraStar and DuraStar medium-duty vehicles.
Jim Balkonis, technical marketing manager with International, said one of the engine’s biggest advantages over its competition is its block is now constructed from compacted graphite iron (CGI), much like its big bore brothers, the MaxxForce 11 and 13.
“The heart of the engine starts with the engine block,” Balkonis said. “If you have a weak engine block, you’re going to have a low B50 rating on your engine.”
He noted the CGI block adds 75% more tensile strength, 40% better stiffness and 200% improved fatigue compared to conventional gray iron. The use of CGI, combined with the use of a ductile iron bedplate for improved perimeter reinforcement, have enabled Navistar to increase the B50 life of its MaxxForce 7 from 350,000 miles to 500,000, meaning 50% of all MaxxForce 7s will still be running strong at the 500,000-mile mark.
Also new is a floating core EGR cooler the company says will result in greater reliability than the fixed EGR cooler used by competitors.
“We identified that as a point that we needed to improve on our engines,” Balkonis said, noting most EGR failures are caused by thermal expansion and contraction in extreme temperatures. “The floating core EGR allows for expansion and contraction.”
Navistar has also gone to a new generation EGR valve, moving from a one-way power with spring return design to a power-open/ power-close design that the company says will eliminate spring fatigue and breakage. Balkonis said every other manufacturer in the industry is still using a spring return, single actuation EGR valve design, which is prone to failure.
Also unique to the MaxxForce 7 are dual sequential turbochargers, which Balkonis says provide improved performance by eliminating turbo lag. A small, fixed geometry turbo helps launch the vehicle and a larger turbo takes over at higher speeds.
Anticipating that competitors will point to replacements costs as a reason for using a single turbo, Balkonis pointed out it costs just $180 more to replace both turbos than to replace the single variable geometry turbocharger found on a Cummins.
Balkonis also spoke of the advantages of vertical integration, most notably that the engine doesn’t have to be designed for use in a wide variety of OEM chassis. This allows for little enhancements like combining the water-in-fuel sensor with the fuel cooler, Balkonis noted.
When comparing warrantees, Balkonis said the MaxxForce 7’s three-year basic warranty is a full year longer than the standard coverage offered for the Cummins ISB and Hino’s JO8E. While he acknowledged both competitors offer protection for unlimited miles while the MaxxForce does not, he said the 150,000 miles covered by the basic MaxxForce warranty will be more than enough in most medium-duty applications.
“The bottom line is, we have a third more time coverage on our basic warranty. How many medium-duty applications get to more than 50,000 miles per year?” he asked.
The most obvious difference between the MaxxForce 7 and other medium-duty engines is its EPA2010 emissions compliance strategy. Unlike Cummins and Hino and every other player in the market, International engines will not use selective catalytic reduction (SCR).
All NOx emissions will be eliminated in-cylinder and through what Balkonis described as the “five core fundamental principles of diesel engine combustion”: control strategies; mixing capabilities; air management; exhaust management; and fuel management.
He countered claims from competitors that International engines won’t be able to comply with stringent NOx emissions standards without exhaust aftertreatment: “You can tell when someone is scared, because they go after your credibility,” he said. “They say ‘Oh, it won’t work,’ when their lead engineers know that it will work. It just took time, money and passion to develop this technology. This is the best solution for the customer…it doesn’t come in and out of compliance based on the responsibility of the driver.”
In concluding, Balkonis said the MaxxForce 7 “has the ratings, the durability, the serviceability, longer standard warranty coverage and it runs clean all the time.”
Available in International Dura-Star and TerraStar medium-duty vehicles, the MaxxForce 7 comes in four ratings: 220 hp, 560 lb.-ft. torque; 240 hp, 620 lb.-ft.; 260 hp, 660 lb.-ft.; and a new 300-hp version with 660 lb.-ft. of torque.