SIX months late according to the EPA and competitors, but right on time by its own estimation, Caterpillar has introduced its full line of truck engines for highway use. The new C7, C9, C11, C13, and C15 engines meet the standards set for exhaust emissions that were imposed by the Environmental Protection Agency on October 1, 2002. The new engines, which use proprietary Caterpillar ACERT combustion and exhaust treatment technology instead of exhaust gas recirculation, were shown during the Mid-America Trucking show in Louisville, Kentucky, March 19 to 21, 2003.
Caterpillar claims that fuel economy for the new engines is equal to that of its 2001 model engines and three to five percent higher than engines using exhaust gas recirculation. By the time the new ACERT engines reach full production in October 2003, Cat will have more than 10.2 million miles of testing available for them.
The new technology utilizes an efficient combustion process built around flexible fuel injection. Electronic controls with proprietary algorithms provide engine settings for the lowest possible oxides of nitrogen emissions and highest fuel economy. Engines in the heavy-duty line use conventional turbochargers with electronic waste gates. These are coupled with hydraulic-assist valve controls for flexible air management.
The small displacement C7 and C9 engines use conventional single turbochargers. The heavy-duty C11, C13, and C15 engines use two standard turbochargers coupled in series to split the work once done by a single turbocharger. Reducing the total stress on each of the two turbochargers increases component life and using already proven waste gate technology enhances intake system reliability. The entire system is designed to provide a carefully metered flow of cool, clean air for engine operation with the result that emissions are lowered while fuel economy and throttle response are improved, Cat says.
The air intake system is designed to control air volume based on engine speed and load. The engine adjusts airflow as needed to allow higher boost levels and the flow needed for high performance and fuel economy. It uses variable valve actuation controlled by engine electronics.
The new C11 and C13 have a redesigned cylinder head built for variable valve actuation. The new head is designed to allow engines to be built with an optional compression brake. All heavy-duty Cat engines will be available with the optional compression brake by 2004. The heavy-duty engines, including the C15, use the same mechanically actuated electronically controlled unit injector system already in use on Cat engines.
The C7 and C9 engines use the same hydraulically actuated electronically controlled unit injector fuel system that has been used on all Cat medium-duty engines since 1997. This electronic system injects small amounts of fuel at the appropriate times to achieve low emissions and high fuel economy.
The injection and air management systems control the combustion process to reduce NOx emissions, while a diesel oxidation catalyst is used for exhaust aftertreatment to reduce particulate levels. Exhaust aftertreatment has been used on Caterpillar medium-duty engines for several years and was introduced to the heavy-duty line in October 2002.
The C7 replaces the 3126E as Cat's primary medium-duty engine. It is available with horsepower ratings from 190 to 330 and torque output from 520 to 860 lb-ft. For ratings above 210 hp, the C7 uses single piece steel pistons. The C7 becomes available in June 2003.
The C9 and C11 engines are designed for vocational and regional applications. The C9 is rated at 335 or 350 hp with 1,050 or 1,100 lb-ft torque. It is a four-valve per cylinder engine and is currently available. The C11 has horsepower ratings from 305 to 370 and torque ratings from 1,050 to 1,350 lb-ft. Production of the C11 begins in December 2003.
For heavy-duty applications, the C13 replaces the current C12 engine. The C15 remains the largest truck engine in the Caterpillar line. Horsepower ratings for the C13 range from 335 to 505, and torque ratings run from 1,350 to 1,650 lb-ft. The C15 tops the ratings list with 435 to 550 hp and 1,350 to 1,850 lb-ft torque. The C13 and C15 are available in October 2003.