MaxxForce 11 and MaxxForce 13 big bore engines are engineered specifically for International Class 8 trucks using compacted-graphite iron (CG Iron) technology for a lightweight block. International developed proven base engineering from its collaboration partner, MAN, in Germany, for U.S. EPA emissions with high pressure common rail fuel injection, twin series turbochargers, exhaust-gas recirculation and aftertreatment technologies. Because CG Iron has greater inherent strength, thinner castings are said to achieve durability equal to that of an engine block cast from gray iron hundreds of pounds heavier. The MaxxForce 13 engine, for example, weighs 300 pounds less than one of the market's leading 13-liter engines. International says its advanced fuel- and air-management provide response to reach peak torque at 1,000 rpm for earlier acceleration upshifts and fewer grade-climb downshifts. This is said to keep MaxxForce big bores operating more in the lower speed range — where fuel economy is inherently better.