First Drive : 2004.5 Dodge Ram HD
By: Mike Magda ©, 2004
Posted: 01-27-04 23:10

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The performance numbers for the reengineered 5.9-liter “600” Cummins diesel engine in the 2004 1/2 Dodge Ram 2500/3500 are not only awesome, they’re the best of any heavy-duty pickup:

  • 600 lb-ft of torque at 1600 rpm
  • 440 lb-ft at 1000 rpm; at least 555 lb-ft from 1400 to 2900 rpm
  • 325 horsepower at 2900 rpm

Want another number just as incredible?

  • Oxides of nitrogen (NOx) levels: 2.5 grams per horsepower per hour (g/bhp-hr);

Engine builders can easily boost horsepower. The aftermarket does it with bolt-on kits. Crank up the turbo, pump up the fuel line pressure, smooth out the intake airflow, reduce the backpressure, and then slap the motor on a dyno and smile. But increase power and reduce harmful emissions at the same time…well that takes some serious numbers crunching. Cummins and Dodge engineers not only gave the Ram engine 45 more lb-ft of torque and 20 more ponies over the 2003 High Output (HO) version, they lowered NOx levels by 40 percent.

The 2004 diesel standards are just the first step. Cummins and all other diesel manufacturers are required to do it all over again for 2007 when federal emissions laws get even tougher. Particulates—which remained unchanged for the 2004 regulations—must be slashed 90% to 0.1 g/bhp-hr. The new NOx limit will be 0.2 g/bhp-hr, although manufacturers will have until 2010 for their entire fleets to comply. Between 2007 and 2009, they’ll be able to certify their engines at 1.1 g/bhp-hr, but after 2010, diesel engines will be nearly as clean as gas engines.

The good news is that stunning advancements in diesel technology have made it easier to design cleaner, quieter and more fuel-efficient engines in heavy-duty trucks. If the current trend continues, owners won’t have to give up torque, towing capacity or payload when the next round of regulations go into effect.

“We had no intention from the beginning of sacrificing horsepower or torque to meet emissions standards,” says Paul McAvoy, senior technical advisor at Cummins, when reminded of how severely horsepower levels were reduced in the ‘70s when emissions regulations and fuel economy standards were first imposed.

Under the hood of the Ram 2500/3500 pickups, the new Cummins 5.9L “600” engine is a gem of consistency. Dodge recently assembled a variety of cab configurations and GVW ratings for the press to drive in the mountains outside of Santa Barbara, California. From the surprising and spirited acceleration of a 4-speed-automatic 2500 2WD regular cab to the dominating towing ability of a 3500 crew cab with a 6-speed manual, the Cummins never disappointed. To those experienced in driving the previous generation Dodge Ram heavy-duty, the improvements were quite noticeable in overall power, suspension stability and interior comfort. To those with seat time in the new 2500/3500 trucks but with the previous Cummins engine, differences in noise reduction and throttle response were most apparent.

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