LOUISVILLE, Ky. International Truck and Engine Corporation believes the integration it is able to provide between truck and engine is key differentiator in its market space and it used the continents largest truck show to showcase its line of 08MY International Star series trucks along with its new MaxxForce engines.

International revealed the power and torque ratings for its MaxxForce 11 and MaxxForce 13 Class 8 diesel engines, which provide up to 1,700 lb.-ft. of torque at 1,000 rpm. Theyre the most powerful in a family of six engines models that offer ratings in the ranges of 330 to 475 horsepower.

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

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 big bore design, which includes a high-pressure common-rail fuel system, twin-series turbochargers with interstage cooler, and a heat-management system, boasts an unprecedented level of integration with Internationals trucks, according to Jacob Thomas, vice president of Internationals Big Bore Diesel Engines Business Unit.

These new engines provide clear advantages over traditional Class 8 big bore diesels, Thomas said. Were providing power and performance that drivers can put to work, and new levels of efficiency that owners can take to the bank.
The advantages include fuel- and air-management systems that provide instant response to reach peak torque at 1,000 rpm. This means earlier acceleration upshifts and fewer grade-climb downshifts and keeps MaxxForce big bore engines operating more often in the lower speed range where fuel economy is inherently best, Thomas explained. Other 11- and 13-liter engines do not achieve peak torque until higher engine speeds, he claimed.

Our goal is best-in-class fuel economy, which is extremely important to Class 8 truck owners, said Thomas. Because even one-tenth of a percentage improvement in fuel economy can mean huge savings, the capability for unprecedented fuel economy is a key part of the basic design of these engines.

The MaxxForce 11 and MaxxForce 13 engines high-pressure common-rail fuel system controls fuel with great precision at very high pressure, according to Thomas. This yields more complete combustion and fuel efficiency, he explained.
The electronically controlled common-rail design introduces fuel into the cylinders at very high pressure and in several metered sequences with each combustion cycle. Other Class 8 diesel fuel systems also use high pressure but Thomas claimed they do not achieve high pressure at engine speeds as low as the MaxxForce big bore engines.

Meanwhile the engine’s 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, Thomas said.

Put it all together and the advanced fuel system, twin-series turbochargers along with the patent-pending Eco-Therm heat-management system deliver an optimized balance of power, performance and emissions control, according to Thomas. A 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. 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.

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