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.
