Stop-and-go driving improved International Truck & Engine Corp. is revamping its popular line of T-444E V8 diesel engines to provide more power at low speeds for stop-and-go operations. Earmarked for medium-duty trucks and school buses, these enhanced T-444E diesels will offer wastegated turbochargers and engine warm-up device provisions for all engine ratings.
The new diesels, which began production in August of this year, offer increased horsepower, torque and engine performance curves to improve stop-and-go driving capability under heavy load.
The T-444E now comes in five ratings: 175 hp. with 460 lb.-ft. of torque; 195 hp. with 520 lb.-ft. of torque; 210 hp. with 540 lb.-ft. of torque; 215 hp. with 560 lb.-ft. of torque; and 230 hp. with 620 lb.-ft. of torque. These models can be spec'd on the International 4000 Series medium-duty trucks, International 3000 Series school buses and International 1652 stripped chassis.
In addition, the 175-hp., 195-hp., and 210-hp. T-444E models are specifically designed to meet the needs of low-emissions vehicle (LEV) users. According to International, those engines are fitted with catalytic converters and horizontal muffler and tailpipe systems to meet Clean Fuel Fleet Vehicle requirements.
International is now also offering the Allison 2000 5-speed automatic transmission with its T-444E engines, for medium-duty and bus fleets.
Combined with the enhancements to the T-444E, the Allison 5-speed overdrive transmission will help provide quicker acceleration. The deeper first gear and lockup in the higher gears will speed up acceleration, while the fifth-gear overdrive can lower engine rpm at highway speed.
Allison's transmission will be integrated with International's Diamond Logic electronic control system so that precise shift points can be developed specifically for the T-444E, making the vehicle easier for the driver to handle.
Overall, wastegating is key to the improved drivability of these engines, says Dan Ustian president of the company's engine-building subsidiary, International Engine Corp., because it allows more boost to engines at low speeds. The addition of engine warmup devices allows for faster cab warmup and window defogging in cold climates, he says.
"We listened to drivers' requests for more power at low speeds and answered with increased clutch engagement toque to help them get moving faster with heavy loads," Ustian adds. Clutch engagement torque has increased to 350 lb.-ft., a 6% improvement, on the improved T-444E engines.
