Comparing the Light Truck Diesels
Chevrolet has joined Ram in having diesel engines; both are built in-house, but Ram chose a ZF eight-speed automatic, redesigned somewhat by Fiat Chrysler, while GM uses a ten-speed automatic which it developed with Ford. The two engines have around the same displacement, just under 3.0 liters, but the Chevrolet echos Ram’s big Cummins diesels by having a straight-six form; while VM’s diesel is a V6.
The Chevy Silverado, with its 3.0-liter “Duramax” diesel, is rated at 23 city, 33 highway in rear wheel drive form, and, presumably due to punishing aerodynamics, at 23 city, 29 highway. (The 4-mpg penalty for AWD oddly matches Chrysler’s large cars.)
Power and torque ratings are 277 hp and 460 pound-feet, and, with four wheel drive, the diesel Silverado can tow up to 9,300 pounds, with an 1,870-pound payload. It’s an impressive set of numbers, especially since this is the first Chevrolet light-truck diesel since 1997 and its first ever in-line six diesel for full-size, light duty trucks.
The Duramax engine is inherently balanced, and uses an aluminum block for low weight; it has dual overhead cams and four valves per cylinder. Warm-up is shortened with active thermal management. Stop-start aids in fuel economy. The diesel option costs $2,495 on high-end trucks (the same as the 6.2 liter V8) and $3.890 on the lower-end LT and RST, over the turbocharged 2.7 gasoline engine.
Moving on over to the Ram, we see another 20 pound-feet of torque for a total of 480, the highest in any Class 1 truck; towing capacity dwarfs that of the Chevy, at 12,560 pounds (payload hasn’t been released yet). Horsepower, though, is below the Chevy’s, at 260 (vs 277). The VM diesel has direct injection, a new variable-geometry water-cooled turbocharger, and a dual vacuum pump system. The block is heavier than the Chevy’s, built of compacted graphite iron with a bedplate.
The last VM engine was impressive in use, but had some reliability issues which may make prospective owners pause; then again, it’s hard to judge reliability from stories told on the Internet, and it may have been no worse than any other engine, just more harshly judged because of its Italian origins. It was also the first generation of this series, and the second generation almost certainly was altered to deal with known problems.
This is a good time to be looking for a pickup of any type; competition is hotter than ever, and automakers are tapping the very latest technologies to squeeze the last bit of performance and durability out of their engines, in both test and real-world situations. Chevy and Ram both have competitive and convincing diesels now; they can only hope that Ford gives up some sales in return.
Clark Westfield grew up fixing up and driving past-their-prime American cars, including an F-body Camaro and Mopar V8s. He has ghostwritten auto news for the last few years, lives in Farmingdale, New York, and can be reached at +1.516-531-4021.