The all-new optional high-output turbo-diesel 6.7-liter Cummins inline-six-cylinder powering the all-new 2019 Ram 3500 is the first engine in the heavy-duty pickup class to reach 1,000 pounds-feet of peak torque. And although the engine's size is the same as the one it replaces, and it looks similar to the previous iteration, there are several changes and upgrades. In fact, it was almost 12 years ago that the Ram turbo-diesel motors went to 6.7-liters in size and provided a maximum rating of 350 horsepower and 650 pounds-feet of torque. Now, the max rating for the new 6.7-liter engine is 400 hp at 2,800 rpm and 1,000 pounds-feet of torque at 1,800 rpm.
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From what we gathered after talking to Cummins and Ram engineers, Ram's initial request was to be the first truckmaker to hit a four-digit number in torque. Cummins responded by getting it done within the same size constraints: a 6.7-liter inline-six-cylinder motor. First, Cummins engineers created the new block from compacted graphite iron, which gave them a stronger, stiffer block to better dampen vibration. It also shaved weight from the engine, another Ram request. When combined with several other weight-saving changes, the new Cummins engine weighs 60 pounds less than the one it replaces.
This new generation of the Cummins B motor also offers a new cast-iron cylinder head that includes new exhaust valves and springs and now roller rockers to drive over the lighter hollow camshaft. Further, the new Cummins also sports new, separate aluminum oil and water pump housings for weight savings as well. Additionally, the piston heads are lighter, stronger and offer lighter lower-friction rings with newly forged connecting rods and bearings. And the new fuel system includes more computer controls that feature a 29,000-pounds-per-square-inch fuel pump and fuel rail for more precise delivery.
Finally, an all-new stronger exhaust manifold is the mounting point for the upgraded variable-geometry turbocharger, which now has a laminated heat shield and a larger set of veins on the exhaust side of the turbo (the impeller size on the intake side stayed the same).
Of course, it stands to reason that with the stronger engine, Ram needed to improvement the transmission as well. The Aisin AS69RC six-speed automatic still has the same gear ratios but includes a brand-new dual-core processor controller with more than double the memory of the previous system. The new transmission benefits from stronger planetary gears and a new heat treatment system designed to significantly widen the range of optimum operating temperatures. Additionally, the torque converter has a dynamic dampening setup to smooth out the possibility of a hard 1st-to-2nd or 2nd-to-3rd shift because of the massive amount of low-end torque.
All these changes sound impressive, but we'll have to withhold judgement until we get a chance to drive the high-output version to see how well the new Cummins works with the new transmission and computer controls. That won't be until the end of February or beginning of March. We're interested to see if this new high-output setup is better than before as the previous version gave us some problems with a few hard shifts and sluggish pulling power off the line during our .
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