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 numbers
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, working
with Isuzu, 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, Honda 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.
