Way back in 1939, Dodge completely redesigned its truck lineup, building them in a brand-new facility that was, at the time, the largest truck factory in the world. It also made its own diesel engine, which it dropped into its heavier-duty models.
Diesel engines were rare in all trucks, and this one only lasted a few years. Then fast-forward to 1978, when Dodge offered its light-duty trucks with an optional diesel made by Mitsubishi, since Chrysler owned a stake in that Japanese automaker. It too was short-lived. Instead, lasting success came in 1989, when Dodge equipped its heavy-duty Ram trucks with an engine made by Cummins.
The diesel engine dates to 1893, when German engineer Rudolf Diesel patented his design for it. It was far more efficient than a steam engine, and compared to the rudimentary gas engines of the day, produced as much power but consumed far less fuel. His big stationary diesel engines were used in industry, but even when small versions were developed, there wasn’t a lot of interest from car builders.
Enter Clessie Cummins. Born in 1888 in Indiana, he was fascinated by machinery and reportedly built a small, working steam engine when he was just twelve years old. In 1908 he was hired as a chauffeur by a banker, who later financed Cummins so he could open an automobile repair shop.
1989 Cummins 5.9L diesel Photo by Stellantis
Cummins thought there was a future in the diesel engines other companies were ignoring. Shortly after he founded the Cummins Engine Company in 1919, he produced his first, a single-cylinder diesel making six horsepower. Once Cummins ironed out engineering issues with his designs – and later almost sold his company to General Motors – cars carrying his engines competed in the Indy 500; a truck powered by one made a publicity run from New York to Los Angeles on eleven dollars in fuel; and Cummins engines powered many of the military trucks in the Second World War. In 1939, when most vehicles were sold with a 90-day warranty, Cummins covered his engines for 100,000 miles (160,000 km). Clessie Cummins retired from his company in 1951 and died in 1968.
Dodge didn’t have a huge slice of the truck market, and it didn’t update its offerings very often. Its 1961 models lasted virtually unchanged until 1972, and that generation soldiered on for more than a decade. By the mid-1980s, sales were in sharp decline, and something had to be done. Dodge decided a new engine might shake things up.
The 1989 trucks looked the same as before, but the three-quarter- and one-ton trucks could now be optioned with a 5.9L Cummins inline-six diesel. GM and Ford offered diesels, but only the Cummins was turbocharged and had direct injection. It made 400 lb-ft of torque, while Chevrolet’s 6.2L V8 made a maximum of 248 lb-ft, and Ford’s Navistar-sourced 7.3L V8 produced 345 lb-ft of torque.
Cummins had been making the engine since 1984, and mostly sold it to companies that made farm and construction equipment. Dodge had to strengthen the truck’s frame and suspension, and improve its cooling system, to handle the heavy engine.
The 2007 Ram was delivered to customers with a tank of B5 biodiesel Photo by Stellantis
Dodge sold 17,000 copies of the diesel truck that first year, and could have filled another 10,000 orders if it had the extra production capacity. By 1991, it had rolled 100,000 diesel-equipped pickups off the assembly lines.
Prior to the diesel, Dodge’s truck sales had been in freefall. Rumour has it the automaker was considering getting out of the truck business overall. It still didn’t top its Detroit rivals for sales numbers overall, but within the first few years of the engine’s availability, half of all Dodge trucks made went out the door with a Cummins under the hood. Many credit the diesel for saving the automaker’s truck division.
The choice to go with Cummins wasn’t out of the blue. Dodge had made a few large trucks beginning in the 1930s, and in 1960 produced tilt-cab highway trucks that included engines from Cummins. It closed that side of its business in 1975. Ford and General Motors also had big-truck divisions, and both used Cummins diesels in some models as well.
Ram announces 865 lb-ft of torque for 2015 Photo by Stellantis
Dodge completely updated its pickup trucks for 1994 with unmistakable big-truck styling, and it proved popular enough that Ram sales tripled over the prior year. The Cummins remained, updated with a new higher-pressure fuel-injection pump to meet tightening emissions standards, and making up to 420 lb-ft of torque.
Then Ford updated its diesel to 425 lb-ft, and the torque wars were on. Cummins supplied the Ram with a new 24-valve 5.9L diesel for 1998, making up to 460 lb-ft of torque. Ford quickly countered with 500 lb-ft, and so Dodge’s diesel was tweaked to 505 lb-ft.
2018 Ram 5500 Chassis Cab Crew Cab 4×4 with 6.7L Cummins engine Photo by Stellantis
In 2007, Ram switched over to a new 6.7L engine, rated at 350 horsepower and 650 lb-ft of torque on its debut. To meet emissions regulations, it was Cummins’ first engine with EGR (exhaust gas recirculation) and a diesel particulate filter. Ram’s heavy-duty models still use a 6.7L inline-six today.
You can follow the power progression: Ram had 930 lb-ft in 2018, while Ford had 935 lb-ft. Ram went to 1,000 lb-ft in 2019; Ford tweaked to 1,050 lb-ft in 2020; and so Ram went to 1,075 lb-ft in 2021. While Ford hasn’t upped its engine yet, it’s likely just a matter of time. (GM, with a maximum of 910 lb-ft, tends to sit back and let the other two fight it out.)
In 2008, Dodge announced that its light-duty 1500 would get an all-new Cummins turbodiesel engine “after 2009.” It never happened. Chrysler declared bankruptcy in 2009 during the financial crisis, and emerged from it as part of Fiat. The Ram 1500’s 3.0L V6 EcoDiesel, introduced for 2014, came instead from Italian supplier VM Motori. But even so, the Cummins relationship, for heavy-duty at least, remains alive and well.
Keyword: Rearview Mirror: How Cummins diesels saved Dodge trucks