International Evolves In-Lines For '07
Steve Sturgess
Executive Editor
International says changes in its inline-six-cylinder engines to meet the 2007 emissions regulation are evolutionary. That means most of the hardware is unchanged, although additional EGR, a new wiring harness and faster electronic controls will be featured.
Additionally, a diesel particulate filter and a no-maintenance closed crankcase breather will also be included on all the 2007-compliant engines.
The engines are ranged under the MaxxForce product name, with the MaxxForce DT based on the familiar DT 466, and the MaxxForce 9 and MaxxForce 10 from the DT and HT 570 models. The new engines cover power ratings from 210 to 350 horsepower with torque from 560 to 1,150 pounds-feet.
Most of the current ratings will carry over, though there's a new higher 300-horsepower rating for the MaxxForce 9 and a top rating of 350 horsepower for the MaxxForce 10, up 10 horsepower from the HT570 it replaces.
Changes to the engines are mostly external, though there is a change to Mahle Monothern steel pistons from previously used articulated steel/aluminum pistons. Despite the material change, the new pistons are lighter. And they are more dimensionally stable, enabling closer tolerances in the wet-sleeve engines for improved combustion and oil control.
On the outside, the exhaust-gas recirculation system is configured with split coolers for the higher flowing exhaust. The engine-coolant-supplied EGR valve is located high on the engine and positioned between the two coolers. Variable geometry turbocharging is used and the engine ECU is now a 32-bit controller to provide faster response and to handle additional inputs for the aftertreatment diesel particulate filter that will be featured on all engines. This new controller is a single box unit, meaning far fewer connections than the previous two-box solution.
Better electrical connections around the engine are promised by the addition of a foam-molded harness. Phil Gronberg, chief engineer for the in-line medium engines, explained that the semi-rigid harness is conformed to fit the engine, putting connectors right at the components they serve. As well as improving first-time fit and quality, the harness also saves service problems from stretched wires, bent pins or the rubbing and chafing that happens with plastic-tape-wrapped harnesses.
Fuel injection is largely unchanged, with the G2 hydraulic electronic unit injectors (HEUI) feeding fuel to the combustion chambers at 2,400 bar (35,000 psi). The multi-event system has been used on International Green Diesel engines since 2004 but has a new wrinkle for '07 with a late post-injection of fuel to initiate active regeneration in the DPF. The added fuel, after combustion, raises the temperature in the exhaust stream so regeneration of the entrapped carbon can occur when needed. At the announcement, Gronberg said this could occur in as short an interval as every 200 to 400 miles, though it is highly dependent on the duty cycle. However, the '07 controls and optimization of transmission matching – with additional offerings of Allison and Eaton automatics – means fuel economy is unchanged for '07. There are even some applications where fuel economy has improved, such as P&D.
The '07-compliant engines will be available across the extremely wide variety of applications of International Class 6 and 7 trucks and Class C and D school buses. Trucks and buses built with these engines will be sold as 2008 model year vehicles.
Equipment continued...
