Building on technology first introduced for the VT 365 medium-duty V-8 diesel truck engine, International Truck and Engine Corporation has introduced a new line of six-cylinder engines for its 4000, 7000, and 8500 series medium and medium-heavy trucks. The new engine line includes an update of International's proven DT 466 as well as an upgrade of the larger DT/HT 530 series to the new DT 570 and HT 570. The engines were introduced to industry representatives during the Society of Automotive Engineers annual conference in Fort Worth, Texas, on November 10, 2003.
Parts of the technology used in the new engines had previously been used with earlier International engines; however, the new engine line combines all the new features into a single design concept. All International engines now use a variable geometry Evrt turbocharger as part of the new air management system. The new turbocharger works in tandem with a newly designed second-generation electro-hydraulic fuel system to optimize turbo boost across the entire engine operating range. In addition, the engines use cooled exhaust gas recirculation to meet exhaust emissions standards set by the Environmental Protection Agency for 2004.
The most immediate result of the new designs is increased displacement for the DT and HT 570. Increasing the stroke of the 570 by 0.4 inch raises the displacement of the former 530 engines 40 cubic inches. In addition, horsepower ratings for all three six-cylinder engines are increased with the bottom of the range for the DT 466 rising to 210 hp from 195 hp and the low end for the 570 rising to 285 hp from 275 hp. Previously, the 466 topped out at 250 hp; the 466 engines now have three ratings above that at 260, 285, and 300 hp. The 300 hp version will not become available until the summer of 2004. Top rating for the 570 engines remains at 340 hp.
Torque ratings for the 466 rise as well. Previously, the DT 466 torque rating topped out at 660 lb-ft. The new engine has two new torque ratings: 800 and 860 lb ft. Torque ratings for the 570 engines remain the same as the earlier 530 engines. Additional equipment on the engines results in slightly increased weight with the 466 gaining 25 lb to 1,450 lb and the 570 increasing total dry weight to 1,560 lb.
The new family of engines provides improved fuel economy and performance akin to engines in sport utility vehicles, says Patrick Charbonneau, vice-president and chief technology officer for the International Engine Group. This improved throttle response results from the combined effects of the variable geometry turbocharger and the new G2 common rail fuel system. The turbocharger has movable vanes that pivot to adjust boost pressure in response to engine speed and load. Changing the boost pressure helps eliminate turbo lag across the entire rpm range. In addition, the new turbocharger allows engines to maintain peak torque longer than is possible for previous engines so that less shifting of either manual or automatic transmissions is required. The new engines have higher clutch engagement torque to provide more power for low speed acceleration. The turbocharger is electronically integrated with engine and fuel systems for optimum performance and fuel efficiency.
The G2 common rail fuel system is similar to technology first developed for the VT 365. It utilizes high-pressure injectors for efficient fuel management, but does so without high-pressure lines that could leak on the exterior of the engines. Injectors are physically much smaller than previous International fuel injectors. This smaller injector diameter provides room in the cylinder head for four valves per cylinder to allow the engine to breathe better. With two intake valves for a more complete air charge in the cylinder before injection and two exhaust valves to clear the combustion chamber of burned gases, the engine can produce more power with cleaner combustion at lower levels of exhaust emission.
Engine oil provides pressure
The injection system uses engine lubricating oil as a pumping medium. A dedicated pump, designed to meet the demands of high system pressures for emissions standards in 2004 and beyond, supplies oil to the common rail at 3,000 pounds per square inch. Inside each individual injector, this pressure is intensified to 21,000 psi for instantaneous fuel injection. The rail is a single piece casting mounted under the valve cover on top of the injectors, which holds down clamping forces to minimize the potential for leaks. In addition to providing pressure for fuel injection, the rail serves as a high-pressure oil source for the engine brake. Injectors for the new family of engines can use fuel containing up to 20% bio-diesel or run on low-lubricity aircraft fuel including Jet A or JP8.
A digitally controlled spool valve provides precise injector operation with faster throttle response. Injector timing controls use two sensors — one to determine crankshaft position and one for camshaft position. The result is more precise injector timing and efficient fuel delivery for lower emissions at high levels of performance.
The new engines are equipped with an exhaust brake and can utilize an integral engine brake. The Diamond Logic exhaust brake works in conjunction with the turbocharger to provide up to 150 hp of braking to the DT 466 engine and up to 185 hp of braking power for the DT and HT 570 engines. The exhaust brake closes the adjustable vanes in the turbocharger to create backpressure in the exhaust system as a braking mechanism. International's integral exhaust brake provides almost identical braking horsepower without adding more components to the engine.
The Diamond Logic engine brake, which uses the exhaust brake to perform some of the work, is available as an option. The engine brake provides 275 hp of braking power to the DT 466 and up to 325 hp of braking for the DT/HT 570 engines. It has a three position selector switch for low, medium, and high power brake settings. The brake operates a slave piston on top of the exhaust valves in each cylinder. The slave piston pushes down on the exhaust valves to release pressure from the cylinder during the engine compression stroke. Engines ordered with the engine brake are equipped with the exhaust brake as a standard component.
Other improvements to the new engine family include a 1/4-inch steel crankcase ladder frame to secure all seven main bearing caps in the DT/HT 570 engines. The bearing caps have been widened for increased strength, which, in turn, reduces noise from the engine. All engines in the new family have a corrosion resistant, powder coated oil pan with dual drain plugs. Providing two drain plugs allows fleet operators to install block heaters for cold weather starting if desired.
In addition to redesigning the six-cylinder engine family, International has made significant improvements at its Melrose Park, Illinois, engine plant. The changes began in October 2002 and have been completed in time for full production of the new engines beginning early in 2004.
To produce the new family of engines, International installed a new crankcase line at Melrose Park that exceeds the ergonomic and safety standards set by OSHA. The production line is designed for 85% uptime and working two shifts a day can reach plant capacity of 75,000 engines a year. Quality and productivity are monitored by workers entering data into a real-time quality management database for instant feedback on machined parts. The line has eight three-axis Computer Numerical Control stations along with in-line gauging to measure parts while the line is running.
The crankcase line has five metal removal operations, two washers, and one manual assembly station. It has a semi-automatic assembly system for automated installation of cam bushings that verifies the force used to install the bushings as well as verifies that they are placed with the correct orientation. Freeze plugs are installed automatically and subjected to a 100% leak test.
A retooled crankshaft line has five new operations including rough machining of the post and flange as well as end drilling operations. The line has two new washers and a two-stage micro-polisher.
Engines and parts are tracked throughout the assembly process. Radio frequency identification tags on the base engine and critical components gather data about each engine and tie the engine and its components to the engine serial number. With this system, International has positive control of the parts used to assemble each new engine.