Peak torque: 1,650
Axle ratio: 3:9
Top gear ratio .74
Rpm limit: 2,000
Additional pounds: 170
Read how other engines performed in Overdrive‘s test drives.
International’s research facility at Fort Wayne, Ind., sits far from any mountains, not ideal terrain for a test drive. Nevertheless, I was able to take an International 9200i day cab south down U.S. 24 to catch perhaps the only decent grades in the region.
Powered by Cummins’ ISX 450, rated at 1,650 pounds-feet of torque, with an axle ratio of 3.9 and a load of 70,000 pounds, the International pretty nearly flattened the 3 percent grades I pulled in a two-hour ride with Mark Conover, Cummins’ marketing strategist. The ISX 450 proved to be a real driver’s engine. As with other EGR engines, it disproved the common belief that EGR will cut horsepower to the ground, which would require dropping one or two gears to maintain power.
I played with the engine on the longest grade, letting it lug down after gaining speed from a red light at the bottom, shifting up to sixth before letting it lug back. I had plenty of torque to grab higher gears, but wanted to check low-end torque. I let the rpm drop to 1,150 before mashing the motor. It picked up very quickly and rose smoothly and steadily through the power band until about 1,450 in each gear. The 450 pulled through sixth, seventh and eighth easily and had plenty left to get us over the top.
On the flat, the ISX 450 demonstrated even quicker throttle response than some of its competing EGR engines, coming on within 100 rpm and climbing quickly to speed. Wherever I applied fuel, the response was the same – not only quick, but smooth up to 65 mph, where I stayed in cruise. On the downside of grades, the Cummins internal engine brake performed well and extremely quietly. Conover says the internal engine brake, which runs on its own cam and develops plenty of horsepower anyway, is even stronger thanks to the simple design of the Holset variable geometry turbo. While it is “variable geometry,” the vanes are stationary, air flow being controlled by a sliding nozzle ring.
Perhaps because the ISX looks so clean, the addition of EGR components is more obvious than on some of the other EGR engines. The cooler is nearly invisible behind the exhaust manifold, even though it runs the entire length of the manifold, but on the other side of the engine piping to the mixer is high and conspicuous. Drivers will have no problem getting to the dipstick or to other systems. The most obvious visual change in International’s under-hood design is moving the radiator surge tank to the right front quadrant of the compartment. The tank, which is pressurized, is part of International’s upgraded waterside cooling system.
John Fehring, engineering program manager, notes that the charge air cooler and radiator are now side by side and the radiator has been lowered about half a foot to accommodate the larger water-side capacity and to draw more air through the grill. “We have not simply accommodated EGR,” Fehring says. “We have taken the opportunity to make other improvements under the hood.”
For example, below the radiator two mega-brackets have been moved outboard to cut the torque on the rails and engine brackets as well as to accommodate the radiator. The position and strength of these brackets also eliminate vibration in the cab’s floor, serve as mounting for springs and bumper, and hold up the increased capacity cooling system. This innovation and the accessory drive pads and mounting locations reflect the smooth integration of the Cummins-International partnership.
Like other engine manufacturers, Cummins has held the line on service intervals and, after 6 million miles of real-world testing, expects no drop in engine life. Owner-operators may also find improvements in length-of-service intervals if they are now changing oil – as most do – at less than 40,000 miles, the benchmark for Cummins EGR engines.