A Real Driver's Engine

International’s research and development facility in Ft. Wayne, Ind., sits conspicuously at the edge of the city, far from any serious mountains. Out here, finding suitable grades for a test drive requires a little research.

The International 9200i day cab I drove south out of Ft. Wayne, down Indiana 24, encountered perhaps the only decent grades in the northwest quadrant of the state. Powered by Cummins’ ISX 450, rated at 1650 pounds-feet of torque, the International, with its new dash and gauge package, pretty nearly flattened the 3 percent grades Mark Conover, Cummins’ marketing strategist, and I pulled in our two-hour test ride. With an axle ratio of 3.9 and a load of 70,000 pounds, this cooled exhaust gas recirculation (EGR) engine proved to be a real driver’s engine. The Cummins power unit contradicts the myths common among some fleet executives and others that EGR would cut available horsepower to the ground, making it necessary to drop one or two gears to maintain torque.

The Environmental Protection Agency’s new regulations put engine manufacturers under the gun to meet the stricter emissions guidelines by Oct. 1. EGR essentially cleans exhaust by capturing it and using it to displace some of the normal air intake. This cools the combustion process and retards the formation of NOX (nitrous oxides), gases that form smog when combined with sunlight and hydrocarbons.

I played with my engine on the longest grade, letting it lug down after gaining speed from a red light at the bottom, shifting up to 6th gear before letting it lug back again. I had plenty of torque to grab higher gears, but I wanted to find out just how much low-end torque Cummins had built in to the new engine. I let the rpm drop to 1150 before mashing the motor. It picked up very quickly, and rose smoothly and steadily through the power band, flattening out nicely at about 1450 and continuing to provide ample pulling power until the horsepower began work in its most efficient rpm range. Horsepower peaks at 2000 rpms.

On the flat, the ISX 450 demonstrated quick throttle response, coming on within 100 rpms and climbing quickly to speed. Whenever I applied fuel, there was this same quick response. Indeed response was not only quick, but it was also smooth up to 65 miles an hour, where I stayed in cruise. On the down side 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 Holsted Variable Geometry Turbo. While it is still called a variable geometry turbo, the vanes themselves are stationary, air flow being controlled by one nozzle.

Perhaps because the Cummins ISX is such a clean looking engine, the addition of EGR components is more obvious than with other EGR power units. 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 up high and quite conspicuous. There is also a very large pressurized surge tank on the passenger side in the right top quadrant of the engine compartment held by two brackets. But neither drivers nor mechanics will have a problem getting to the dipstick or to other systems under the hood.

John Fehring, Engineering Program Manager at Cummins, 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 draw more air through the grille.

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. They also serve as mountings for springs and bumpers and hold up the increased capacity cooling system.

This innovation, along with the fact that engine accessory drive pads and mounting locations come with every Cummins that International puts in its trucks, are examples of the kind of non vertical integration the Cummins-International partnership has accomplished. They demonstrate that EGR technology has proved to be an opportunity for other non-EGR improvements, according to Fehring.

Beyond performance, concerns about maintenance, longevity and fuel mileage remain in the minds of some owner-operators and fleet executives. Like other engine manufacturers, Cummins – with 6 million miles of real world testing – has held the line on service intervals and expects no drop in engine life.

Conover notes that some operations might even see increases in fuel mileage depending upon the engine they now drive. Owner-operators in particular may find improvements in length of service intervals if they are now changing at less than 40,000 miles, the benchmark for Cummins new EGR engines.

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