Cummins and Dodge established a partnership at the end of the nineteen-eighties that saved the latter’s trucks division from oblivion and established the former’s formable reputation as a manufacturer of the sort of diesel motors that every truck owner fantasized about.
Even though Dodge’s truck division has separated from its parent and RAM is now a recognized brand in its own right, that thirty-year partnership with Cummins is still going strong, and RAM continues to use Cummins motors to power its trucks.
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4th Generation Cummins 6.7 Liter
RAM first started using the six-point seven liter Cummins engine when the model switched over in two thousand and seven in order to comply with increasingly stringent emissions standards and as a way to increase the power that their HD trucks made.
After all, if there was one thing that RAM understood it was their customers, and they wanted to ensure that they had all of the extra power that their customers were increasingly beginning to demand and that they complied with the increasingly tough emissions standards that both the EPA (Environmental Protection Agency) and CARD (California Air Regulation Board) set.
However, it wasn’t until thousand and ten that RAM started using the fourth-generation six points seven liter Cummins motor in their HD (Heavy Duty) trucks. It would become the motor of choice in all of RAM’s HD trucks until two thousand and eighteen when another model change meant that RAM needed to use another new Cummins motor.
4th Generation Horsepower And Torque
Another of the lessons that RAM and Cummins had learned during their partnership was that different drivers demanded different things from their trucks. That demand led to Cummins designing, engineering, and manufacturing a number of different six point seven variants, which means that there wasn’t a set amount of horsepower and torque that the motor made. It varied according to the version of the motor that the truck used.
And to complicate matters even further, during the lifespan of the motor, Cummins managed to squeeze an additional thirty-five horsepower out of it and add an additional two hundred foot-pounds of torque.
The easiest way to differentiate the power performance figures is by comparing the most desirable HD model of two thousand and ten (the manual G56), which made three hundred and fifty horsepower and produced six hundred and fifty foot-pounds of torque with the top of the range two thousand and eighteen HD model, the Aisin Auto, in which the six-point seven Cummins made three hundred and eighty-five horsepower and a staggering nine hundred and thirty foot-pounds of torque.
And the two things that made all the difference between the power that the motor made during those years was the transmission that it was coupled to and Cummins’s unrelenting desire to continually improve their motor.
Towing and Acceleration
Thanks to its more than impressive torque generation and three hundred and fifty horsepower, the two thousand and ten G56 RAM will hit sixty miles an hour from a standing start in around eight seconds and comfortably idles at around fifteen hundred rpm (revolutions per minute) while doing seventy miles an hour with close to two thousand pounds of weight in its rear bed.
That means that you should comfortably get between sixteen and twenty miles from a gallon of diesel even when you’re running a fully loaded truck. And while we are on the subject of load, it’ll also carry up to five thousand one hundred pounds of weight in its bed, and can easily tow close to eighteen thousand five hundred pounds. Whatever you’re hauling in your trailer, the two thousand and ten RAM and its six point seven Cummins can pull it down the road.
Conversely, the last year of the RAM to use the fourth-generation six point seven Cummins the two thousand and eighteen will go from zero to sixty in around half a second less than the original fourth generation Cummins powered truck thanks to its additional thirty-five horsepower and the extra two hundred and eighty foot-pounds of torque that helps it to get off the line.
All of the extra torque also increased the towing and load capacity of the RAM and depending on the wheel configuration and whether you were behind the wheel of a 2550 or 3500 had a towing capacity of anywhere between eighteen thousand and thirty-one thousand pounds.
When you couple that with the five thousand pounds that it could carry in its bed, it means that if you wanted to up sticks and move your entire house across the country, all you needed to do that was the fourth generation Cummins powered 3500 RAM HD.
RAM Transmissions and the 4th Generation 6.7 Cummins
Okay, so we were being a little too inclusive when we mentioned the towing and weight capacities, as the only 3500 model that was actually capable of hauling and towing that kind of weight with the Cummins up front, was the version that was fitted with the ridiculously efficient and powerful Aisin transmission.
The problem was, and is, that a lot of diesel truck drivers don’t actually like the Aisin as it’s an automatic rather than a manual transmission and they think it lessens the control they have over the amount of power that they want the motor to make.
But whatever their collective opinion was, and is, there’s no denying that the Aisin transmission coupled with the fourth generation six point seven Cummins was a devastating combination.
4th Generation 6.7 Cummins Emissions
As we’ve already mentioned, two of the main reasons why Dodge decided to switch the five-point nine-liter Cummins that they were using in the RAM to the six-point seven was an increasing demand for more power from their customer base and tighter EPA and CARB emission regulations.
The six-point seven Cummins, as well as filling all of the additional power requirements that RAM’s customers wanted was also fitted within a DPF (diesel particulate filter) as standard, which meant that it met all the standards set by both governing bodies. And remember how we also mentioned that Cummins liked to tinker and improve their motors?
In the intervening eight-year period that the fourth generation six point seven was used to power the RAM, Cummins also added both EGR (exhaust gas recirculation) and SCR (selective catalytic recirculation) systems to their motor, to meet the additional emissions standards that were introduced during that time.