The Cummins ratings for 2007 heavy-duty engines include three new ISX models — the 425 ST (Smart Torque), the 485 ST, and the straight ISX 600. The new ISM features enhanced fuel economy, the company says, and includes a new 410 hp
rating. ISM models start at 280 hp, with torque values from 1150 to 1550 lb ft.

The ISX 425 ST provides 1550 lb ft of torque rising to 1750 lb ft in the top two gears, where driveline stresses are lightest. This allows the spec’ing of lighter axle and driveline components. It also means drivers stay in top gear longer, maintain road speed better, and shift less often on grades, bringing better fuel economy.

With the ISX 485 there’s a choice of either straight or Smart Torque ratings – 1650 or 1850 lb ft, or an ST combination of both. For owner/operators and heavy haulers, there’s the new ISX 600 with 1850 lb ft of torque.

Eleven other straight ratings start at 400 hp and go to 550/1850. The six other Smart Torque models start at 385 hp ranging up to 500 hp. All Cummins ’07 engines use cooled exhaust gas recirculation (EGR), combined with high injection pressures, a particulate filter, and the Holset VG turbocharger now with electronic actuation.

Both the ISX and ISM will be available in limited production in fourth-quarter 2006, with full production beginning in January 2007.