. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Casting innOVatiOns
I Navistar Launches First V8 CGI Block
n order to improve the fuel economy of its diesel engines, Navistar, Warrenville, Ill., needed to fi nd a way to make a lighter engine block. For more than
10 years the company had been re- searching and developing blocks using compacted graphite iron, which offers higher strength, stiffness and fatigue strength than gray iron. After success- fully completing prototypes and then production V6 engines in the last few years, Navistar launched the Maxx- Force 7 in 2010, the company’s fi rst V8 series production engine produced in CGI. In 2004, Navistar designed
and built a lightweight V6 en- gine with a CGI block, which resulted in an 80-lb. weight reduction compared to the baseline gray iron component. In 2007, the truck engine manufacturer began series production of its first CGI block for the new MaxxForce 11 and 13 big bore engines. “When we combined
all our accumulated design and development experience with technological advance-
ments in CGI machining, that material became our logical choice for the 2010 MaxxForce 7 cylinder block,” said Rob- ert Olszewski, manager of base engine design at Navistar. “We were sold on CGI’s superior strength and fatigue life, which positively infl uence engine performance and weight.” According to Olszewski, CGI offers
75% higher strength, 45% higher stiff- ness and double the fatigue strength
of gray iron, so engine designers are able to put more engine performance into a smaller package, which translates into reduced weight and better fuel economy.Engine designers at Navistar designed the MaxxForce 7 engine block specifi cally for CGI. “In our case, the block had to
deliver optimum total performance,” Olszewski said. “It had to have su- perior mechanical properties and be lightweight, easy to cast and machine, and affordable.” Special attention was given to the core pack- age, which met engine designers’ objectives and was casting- and machining-friendly, ac- cording to Olszewski. “All those consider- ations enabled us to meet not only our func- tional objectives but also the cost target,” he said. Navistar is sourcing the engine blocks from Cif-
unsa, Coahuila, Mexico. The metalcaster was challenged to meet Navistar’s dimensional requirements for the thin walls and mechanical properties of the engine blocks, which measure 22.3 x
11.7 x 21.4 in. (566.6 x 296.6 x 544 mm) and weigh 291 lbs. (132 kg). Cifunsa worked with SinterCast, Stockholm, Sweden, which supplies process con- trol technology for high volume CGI casting production. “Cifunsa has had a relationship with
SinterCast since 1997,” said Cifunsa’s chief executive offi cer Alberto Pinones. “They give us the consistency and reliability on process control, as well as a consistent microstructure and lower scrap rates.” CGI production is forecast to represent
2.7% of Cifunsa’s budgetary production this year, according to Pinones, who added that the metalcaster has plans to add new CGI projects in the near future. Pinones said Navistar is forecasting
Navistar’s MaxxForce 7 is a V8 engine with a compacted graphite iron block for medium truck and bus applications.
56 Metal Casting Design & PurChasing
an order of 250,000 blocks annually, with a chance of volumes to double, depending on how well the product does in the light- and medium-duty truck market.
METAL May/June 2010
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