International says its new big-bore diesel is ready to hit the road, in both 11- and 13-liter versions called MaxxForce 11 and MaxxForce 13. The engine is the result of a joint development by International and German truck- and engine-maker MAN Nutzfahrzeuge. It will be manufactured at a new plant in Huntsville, Alabama, starting in April, though early orders will see engines built in Germany and assembled in the U.S.

The engine uses exhaust gas recirculation (EGR), and International claims it will remain the base technology to meet EPA 2010 standards without using selective catalytic reduction (SCR) to achieve lowered NOx levels. It uses a diesel particulate trap, like most other 07-compliant engines, to reduce soot.

The 11-liter engine comes in three ratings – 330 hp/1250 lb ft, 370 hp/1350 lb ft, and 390 hp/1400 lb ft. The 13-litre model offers 410 hp/1450 lb ft, 430 hp/1550 lb ft, and 475 hp/1700 lb ft.

MaxxForce engines will be offered as options exclusively in International ProStar, TranStar, and WorkStar trucks. The company plans to begin rolling out MaxxForce-equipped trucks later this month, starting with a fleet of TranStar regional tractors, currently being assembled at the company’s plant in Garland, Texas.

Highlights of the new engines include a compacted graphite iron (CGI) block, said to be 70% stronger and 40% stiffer — with double the fatigue limit — than traditional cast iron. At 2244 lb, it’s 300 lb lighter than the Cat C13, with an installed weight some 500 lb less with all emissions hardware in place.

A programmable, 26,000-psi, common-rail fuel injection system capable of multiple injection events results in very efficient combustion, says International, with peak torque achieved just above idle at 1000 rpm. The multiple-event injection sequence reduces the clattering noise associated with diesel combustion, resulting in a quiet engine even at high speeds.

The Eco-Therm heat-management system features an innovative, multiple coolant circuit managed by an electronically controlled control valve. There’s no charge-air cooler or air-to-air aftercooler. Instead, there’s a two-stage heat exchanger, using coolant circulated through a radiator. In effect, there are two radiators — one for the engine cooling circuit, the other for the intake-air heat-management loop — enabling flexibility in managing coolant flow and temperatures to create ideal air-intake and exhaust-gas temperatures under a wide range of operating conditions.

Series turbochargers operate in unison, says International. The smaller primary turbo responds quickly to deliver air for immediate take-off at low engine speeds. The larger secondary turbo maintains peak power at high speeds and grade changes. Neither turbo is of a variable-geometry design. The second turbo is waste-gated. The system is said to deliver superior cold weather operation with faster warm-up.

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