By: Mike Magda © PickupTruck.com, 2004 Posted: 01-27-04 23:10 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. Dodge also brought along comparable diesel models from Chevy and Ford for side-by-side tests in hauling 5500 pounds of payload and towing a 13,500-pound trailer. Drivers could quickly switch between vehicles and cover a short mountain course to compare pulling power, ride & handling, interior ergonomics and even such esoteric features as visibility with tow mirrors. With aggressive but manageable low-end torque, the Dodge matched its best-in-class claims against all the competitors. A radar speed gun was positioned below the summit of San Marcos Pass so drivers could record top speed in each vehicle, and the Ram never lost. Dodge engineers invited the press to try other tests while towing, such as side-stepping clutch at idle while parked uphill. The Ford and Chevy often coughed and died but the Dodge recovered with enough torque to pull up the hill under zero throttle. The new Cummins “600” engine simplifies life for the heavy-duty lineup and gives Dodge a strong foundation for an important segment in its overall truck strategy. The venerable V-10 has been dropped from the Ram 2500/3500, although you can get it in the 1500 as part of the wicked 500-horsepower SRT-10 package. The base engine in the 2500/3500 is the new 345-horsepower Hemi, but 73 percent of all Ram heavy-duty customers spend the extra $5,760 to get the diesel option. Dodge used to offer a standard and High Output (HO) diesel engine, and the HO engine was not available in California. Now the Cummins “600” is the only diesel in the Dodge lineup and it’s certified for all 50 states. “California was always under-represented for us,” says Frank Kelgon, vice president of the Dodge truck product team. “Our market share and volume went up but California was stagnant because of the diesel limitations. There’s now a tremendous opportunity for us in California with the “600” diesel.” Cummins’ development of the new Ram “600” diesel is a showcase of technology that will be found on all future diesel engines as emissions standards tighten. A Bosch common rail fuel system capable of handling upwards of 23,000psi (around 4000-5000psi at idle) is the hardware, but a very sophisticated engine management computer makes the fuel-delivery decisions. With electronically controlled fuel injectors and such high pressure in the fuel lines, an injection strategy can be developed to deliver optimum power and a more complete combustion to reduce emissions. Instead of pushing one large spray of fuel into the cylinder on the compression stroke, engineers can program the computer to send small “pilot” injections before and after the main injection. By varying the timing and volume of the pilot injections as well as the main injection, engineers can fine-tune the engine for various loads and rpm. To achieve this precise level of engine management, the computer code went from 350,000 bytes of information to over 550,000 bytes. Cummins also used an advanced computer program to test fuel maps and other engine-management strategies. “This design is based totally off our ability to model an engine on the computer,” says McAvoy. “We can look inside the cylinder and combustion process and achieve a simpler approach to cutting emissions.” The reduction in harmful emissions was achieved without adding exhaust gas recirculation (EGR) or after-treatment equipment. In fact, the “600” engine has only 43 new parts. But when 2007 rolls around, expect the next Cummins engine to have cooled EGR as well as particulate aftertreatment filters or traps. In developing the new “600,” Cummins and Dodge made numerous other improvements or changes to the engine: • Air inlet redesigned to block hot engine air from entering, reducing the intake charge by 30 to 40 degrees. • Intake resonator re-engineered for increased airflow • Larger compressor on Holset turbocharger • Engine cooling improved with new fan assembly and mounting fan shroud to engine for more efficient airflow through radiator • Upgraded intercooler • Upgraded exhaust valves • Tailpipe increased to 4-inch diameter • Improved sealing and gasket materials • Oil-change intervals are now 15,000 miles (vs. 7,500 for competition). • Holset turbocharger gets bigger compression side • Switch to electronic control of wastegate • Upgrades to exhaust manifold • Revised intake ports in cylinder head • New piston bowl geometry • Different spray pattern from injectors The new Cummins “600” now gives Dodge the current edge over the competition from Ford and Chevy/GMC. Just days after Dodge released its numbers in December 2003, Chevy announced the 6.6-liter Duramax would be boosted to 310 horsepower and peak torque of 590 lb ft. GM added a new turbo charger, reworked the engine computer and installed an electronically controlled EGR. Ford did not announce any changes its 6.0-liter Powerstroke, leaving it at 325 horsepower and 560 lb ft. Diesels and heavy-duty pickups are important to the manufacturers, especially at a time when Nissan and Toyota are poised to steal market share in the light-duty truck market. Heavy-duty trucks hardly ever need cash incentives and often sell for sticker price, and 2500/3500 accounts for a third of overall Ram sales. Customers are usually very loyal to their favorite brand, and many light-truck consumers look up to heavy-duty owners for advice and direction when shopping for a pickup. Dodge now has over 28% of the heavy-duty diesel market, recently passing GM and setting its sights on Ford’s dominating share. Considering that Ford sold nearly twice as many F-series pickups last year as Dodge Rams (845,586 units vs. 449,371, according to Automotive News), Dodge’s presence in the heavy-duty market is quite remarkable and continuing to improve. Now that Dodge can boast best-in-class numbers, that share is expected to increase.