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The Dodge/Cummins Partnership: How It All Began.

With Cummins recent multi-year extension of its current agreement with Chrysler (announced earlier this year), some may wonder how the Cummins partnership with Chrysler began. The legacy of the Cummins/Chrysler relationship and the Cummins Turbo Diesel started in the early ’80s.

Early in 1981, Cummins began looking for partners to use its B Series engines in both on- and off-highway applications. Cummins pursued U.S. truck manufacturers and seemed to be pretty close to a deal with GM Truck, but GM decided to go in a different direction. Meanwhile, Cummins proposed the development of a 5-cylinder version of the B Series engine for Ford. However, Ford also decided not to proceed with Cummins as a supplier.

Meanwhile, the same year, Chrysler began actively searching for an appropriate diesel engine. Chrysler talked with several diesel engine suppliers, but for some reason, relationships did not progress. Chrysler was impressed with Cummins and the performance and fuel economy of its 4-cylinder engine, but was concerned about the inherent vibration qualities of an inline 4-cylinder engine. Chrysler determined that the 6-cylinder engine would be too big to fit in their trucks, so they asked Cummins to make a 5-cylinder engine. Cummins entertained the idea, but decided to decline. At this point, the relationship looked like it would not progress.

Chrysler and Cummins maintained contact over the next couple of years and as Cummins learned that Chrysler was considering the Navistar 6.9L for their Dodge trucks, Cummins started to do some serious rethinking. One of the original goals for the B Series engine was for it to be short enough to fit the GM midrange truck, which had a pretty short engine bay. With a little investigation, Cummins realized that its 6-cylinder B Series was the shortest 6-cylinder diesel in existence. That’s when interest really picked up. In 1983, Cummins asked Chrysler for a set of engine compartment drawings for the Dodge pickup to determine if its six-cylinder B Series engine might fit. The results looked positive, which sparked new interest from Chrysler. Cummins then sent Chrysler a non-running engine to install in a Dodge pickup. Chrysler evaluated the installation and felt there were some challenges, but no showstoppers.

The next hurdle was when Chrysler realized that they didn’t have enough resources within the company to take on the engineering task required to install the diesel in a gas pickup. Cummins offered to be Chrysler’s outside engineering contractor, and together Chrysler and Cummins created a new, unique system for Cummins to do the engineering, design and testing under the supervision of Chrysler Engineering. Putting a diesel engine in a gas pickup was no small task. The changes required included:

  • Moving the radiator yoke and radiator forward four-plus inches to make room for the longer engine
  • Changing the fuel system from gas to diesel including an in-tank pump, fuel-return line, fuel filter, heater, and water separator
  • Using a larger battery, cables and stronger battery tray
  • Using a larger-diameter exhaust system
  • Using a stronger drivetrain for the low-rpm high-torque engine: torque converter, clutch, automatic and manual transmissions, front and rear axles, prop shafts, 4WD transfer case
  • Adapting engine to transmission and clutch housing
  • Using a heavier front suspension to support much heavier engine and driveline
  • Increasing the cooling capacity: radiator, shroud, fan, fan drive
  • Adding an engine cooler
  • Adding a vacuum pump for brakes and heater controls
  • Certifying brakes for different weight distribution
  • Changing instrument panel for appropriate diesel function warning lights
  • Adding electric controls for intake manifold heater
  • Utilizing a larger starter
  • Utilizing a large enough alternator to support the electrical system
  • Rearranging items in the engine compartment to fit with the diesel engine
  • Designing the front-end engine accessories to fit
  • Designing many new wiring harnesses throughout the truck

Another challenge was the lack of space in Chrysler’s truck assembly plant. To work around this, Cummins set up a new facility in the Detroit area to dress engines and transmissions sequenced to the truck plant build schedule. The power plants were shipped in exact sequence for truck build in a just-in-time manner.

Although Chrysler knew that the Cummins engine had the best fuel economy, towing capacity and performance, Chrysler forecasted only 10,000 units the first year. Chrysler began taking diesel pickup orders in June 1988 – and by January 1989, they had 22,000 orders from dealers and had to stop taking orders. And the rest is history. Twenty-one years later, Cummins continues to be the exclusive diesel engine supplier for the Ram Heavy Duty, continuing the Chrysler/Cummins partnership and carrying its legacy into the future.

Summary provided courtesy of Turbo Diesel Register.

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