This chart shows the V-6 reaches...
This chart shows the V-6 reaches peak horsepower around 3,700 rpm and peak torque from about 1,700-3,200 rpm. The illustration is from an early version of the 4.2L, which is now rated at 270 hp and 420 lb-ft of torque-right on target to compete with gas
Performance
The V-6 is rated at 270 hp and 420 lb-ft of torque, and the V-8 is good for around 325 hp and 500 lb-ft of torque. These numbers are not set in stone and may rise by the time the engines reach production. In a performance test using a Durango fitted with the Cummins V-6, the SUV reached 60 mph in 9.6 seconds. That's faster than a Durango with the 5.9L gas engine. The 1/2-ton Ram 1500 with the Cummins V-8 hit 60 mph in just 8.8 seconds, which is approximately two-tenths of a second slower than a Ram when fitted with a Hemi 5.7L gasser.
The performance curve for...
The performance curve for the 5.6L V-8 shows about 325 hp and 500 lb-ft of torque. The horsepower peaks at 4,000 rpm, and the torque is realized just under 2,000 rpm and starts to drop off soon afterward. The torque curve will probably be flatter with the final version of the V-8.
Miles Per Gallon
In a test of a Durango SUV with the 4.7L gasoline V-8, engineers measured a combined city/highway rating of 15.3 mpg. The diesel V-6 achieved 22.1 mpg in the same test, a 44 percent improvement. The diesel V-8 in the Ram 1500 did even better with a 49 percent improvement. It scored a combined city/highway rating of 21.7 mpg, compared to a Hemi that was rated at 14.6 mpg. In highway driving simulations, the diesel Durango made 25 mpg and the Ram 1/2-ton sipped just 24.6 mpg of diesel.
Common Rail Fueling with Piezo Injectors
Super-fast-acting piezo injectors are part of the reason the new V-engines are so efficient. By using crystals that change shape in .02 milliseconds when charged with electricity, the injectors are able to actuate much quicker than those driven by solenoids. This improves the accuracy of (up to seven) injections during the power stroke and the exhaust stroke when the particulate filter needs to be heated to clear out trapped particles. The downsides to using piezo injectors are the added cost, the need to use ultra-low sulfur diesel fuel, and slightly raised nitrogen oxide emissions.