LOUISVILLE, Ky. — International Truck and Engine has unveiled the specifications for its MaxxForce 11- and 13-liter “Big Bore’ engines — first announced at the Mid-America Trucking Show in 2005. Both will feature a high-pressure common rail fuel injection system, series turbochargers with interstage coolers, and an innovative heat management system called Eco-Therm.

The MaxxForce 11 is a 10.5-L in-line-six with preliminary ratings of 330-390 hp at 1900 rpm, with 1,250-1,450 lb ft of torque between 1000-1200-rpm. Dry weight of the engine is stated at 2,244 lb.

The MaxxForce 13 is an 12.4-L in-line-six with preliminary ratings of 410-475 hp at 1900 rpm, with 1,450-1,750 lb ft of torque between 1,000-1,200 rpm. The dry weight of the MaxxForce 13, according to International’s press material, is also 2,244 lbs.

Rated M: MaxxForce features include high pressure fuel
system, Eco-Therm technology, higher strength, and lower noise.

“These new engines provide clear advantages over traditional Class 8 big bore diesels,” said Jacob Thomas, vice president of International’s Big Bore Diesel Engines Business Unit. “We’re providing power and performance that drivers can put to work, and new levels of efficiency that owners can take to the bank.”

The advanced fuel- and air-management systems provide instant response to reach peak torque at 1,000 rpm, providing better acceleration on upshifts and fewer grade-climb downshifts – allowing the driver to maintain optimal engine speed for better fuel economy.

High-Pressure Common-Rail Fuel System:

The MaxxForce 11 and MaxxForce 13 engines’ high-pressure common-rail fuel system controls fuel injection with greater precision, introducing fuel into the cylinders at 26,000 psi, providing more complete combustion and improved fuel efficiency.

The advanced fuel system, twin-series turbochargers and patent-pending Eco-Therm heat-management system deliver an optimized balance of power, performance and emissions control. The smaller primary turbo responds very 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. An interstage cooler after the first turbo and an after-cooler following the second turbo reduce the temperature of the intake air increasing its density so that more air can be packed into the engine to achieve efficient, peak performance.

Eco-Therm Technology:

The innovative Eco-Therm heat-management system is made possible by unprecedented engine-truck integration on the MaxxForce big bore engines. It electronically controls coolant flow and temperature across the various coolers to achieve optimal intake-air and exhaust-gas temperatures under all conditions. Intake-air temperature control enables faster warm-ups and engine operation at peak efficiency in cold climates. By maintaining exhaust-gas temperatures at optimal levels, there is an enhanced level of passive regeneration of the diesel particulate filter that leads to improved fuel economy.

MaxxForce’s Other Features:

— Higher strength without added weight. The North American commercial truck market’s first compacted-graphite iron (CG Iron) cylinder block is up to 300 pounds lighter compared to the traditional gray iron that other engine blocks are made from. CG Iron is 70 percent stronger, 40 percent stiffer and has twice the fatigue strength of traditional gray iron. This provides longer service life and higher payload capacity.

— Low noise, vibration and harshness. The high-pressure common-rail fuel system, pronounced cylinder block ribbing and other design enhancements make the MaxxForce big bore engines startlingly quiet (3-5 dBA quieter) compared to current big bore engines. This results in exceptional driver comfort and experience.

Designed and engineered specifically for International’s Class 8 trucks, the MaxxForce big bore engines will be offered in ProStar line-haul tractors, TranStar regional-haul tractors, and WorkStar severe service vehicles beginning in late 2007.

As previously announced, the new MaxxForce 11 and MaxxForce 13 are the first outcomes of the collaboration between International and MAN Nutzfahrzeuge. Both global companies contributed to the design, development, engineering, sourcing, testing and manufacturing of the technologies, systems and components.

The MaxxForce 11 and MaxxForce 13 engines will be manufactured at a new International plant in Huntsville, Ala.