A smooth transition

| June 01, 2006

Key Spec’s as Tested
Engine: ISX ISM
Horsepower: 500 410
Torque: 1,850 1,550
Truck: ’03 Volvo 770 ’05 Kenworth T600
Trailer: 53-foot van 40-foot drop-deck flatbed
GVW: 77,000 pounds 59,500 pounds
Transmission: RTLO-18718B, Eaton 18 speed RTO16910C-DM3, Eaton Autoshift 10 speed
Rear Axle Ratio: 3.73 3.90

Some folks are pessimistic about the new lower-emissions 2007 engines; forecasts of rising costs and falling performance and reliability are common. Just don’t say that to the engineers and scientists who design, build, test and deliver the engines.

The EPA and California Air Resources Board restrictions don’t scare them. They challenge them. And it looks like the challenge is being met.

“I like the idea of clean air,” says Cummins Technical Advisor Glen T. Haegle. “Just give me a reasonable target and time to get there, and let’s go for it.”

Cummins ’07 engines are ready to go, and I test drove them through a variety of road conditions in Indiana to see if the mandatory changes designed to lower emissions would mean changes to the way you’ll drive ’07 tractors or how they’ll feel in your hands.

“It will be hard to tell the ’07 engines from the ’06 engines by appearance,” says New Product Marketing Manager Mario Sanchez. The only visible changes, obvious only if pointed out, are a crankcase breather housing and exhaust recirculation line on the driver’s side and, on the passenger side, a cooling tube and electric actuating motor for the variable geometry turbocharger. Beyond that the new and old engines look the same.

“The basic engines have not changed,” Sanchez says. They have the same block, head, crankshaft, pistons, fuel system, turbocharger, connecting rods, camshafts, gears and flywheels.”

Nor will ’07 emissions compliance change a truck’s appearance. Exhaust systems will have Cummins Particulate Filters (CPF) similar in appearance and weight to the mufflers they replace.

Cummins’ 30 billion hours of testing has turned up no power or torque loss. “In fact, it’s expanding,” Sanchez says.

While appearance can be important, performance is what really matters in the end. So how do the ’07 engines compare to their predecessors? I went to the Cummins headquarters in Columbus, Ind., in March to test drive the ’07 ISX and ISM engines to find out.

The first test vehicle was a 2003 Volvo 770 condo with an ’07 ISX rated at 500 horsepower and 1,850 pounds-feet of torque, an Eaton 18-speed double-over and 3.73 rears. We hauled a 53-foot van. Including myself and technical advisor Pat Shook, who would accompany me for the ISX drive, the rig weighed about 77,000 pounds.

In this case, the CPF was vertically mounted behind the cab.

At the heart of Cummins’ exhaust gas recirculation and after treatment are its proprietary variable geometry turbocharger and CPF. The VG turbo controls the flow of gases through the engine: crucial to effective EGR. The CPF removes soot and ash from the exhaust.

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