Ram has overtaken rivals in the heavy-duty pickup segment. When properly equipped, their 3500-model trucks are rated to tow a segment-leading 31,210 pounds.
Enabling this stellar performance is an updated 6.7-liter Cummins diesel that puts out up to 385 hp along with a best-in-class 900 lb-ft of torque. But how trustworthy are these figures? Could they be bogus? The answer depends on how you measure.
Perusing the Ram 3500’s spec sheet reveals all of its vital statistics, from wheelbase and overall height to turning diameter and crankcase capacity. Eyeballing its engine output figures revealed a curious anomaly; the truck’s Cummins inline-six is rated SAE Gross using the organization’s J1995 standard. This is a different test procedure than what’s commonly used throughout the automotive business.
Car companies most frequently rely on the SAE J1349 when measuring horsepower and torque. Gary Pollak, program manager for technical projects at SAE International said, “[It’s] the spec that the industry uses.” Powerplants for passenger cars, light trucks, SUVs and similar vehicles are tested this way.
Potentially undermining Ram’s claimed figures Pollak said, “No vehicle manufacturer has an engine certified 1995.” Additionally, he noted that the folks at SAE want all manufacturers to use “comparable methods” when measuring engine output, which, at least for now, would be J1349.
Hop, Skip and Jump to Conclusions
However, just because Ram uses a different procedure does not mean its claimed figures are spurious. According to SAE, the J1995 standard is:
Intended for use primarily by engine manufacturers that supply engines to other companies for installation in applications where the engine manufacturer may not control induction and exhaust system design or the speed at which the powerplant runs.
Since Ram buys its diesel engines from Cummins, this rating standard makes sense. Everything appears to be on the up-and-up.
Clarifying their position, Nick Cappa of Ram Truck communications said, “Cummins is an engine-producing company, so when they punch out motors, they’re using them in a number of different applications and it’s not always going to have the same accessory drives,” or intake plumbing or exhaust routing, for that matter.
“We were the pioneers in the large displacement turbo diesels in heavy-duty trucks,” said Cappa. Ever since Chrysler introduced the original 5.9-liter Cummins 27 years ago, he said they’ve used the same exact test procedure, J1995, so it’s not like the folks in Auburn Hills decided one morning they were going to try to game the system by using a different procedure from the rest of their competitors.
Driving his point home, Cappa noted, “Our engineers truly feel the 1995 power ratings provide a more direct reference for comparing heavy-duty engine performance.” This is because these hard-working trucks can be outfitted in countless different ways, with equipment like dual alternators, power-takeoffs and so on, all of which leads to varying parasitic losses, which Cappa said are more accurately taken into account by the J1995 standard.
Thirty-Six Inches, Three Feet, One Yard
Three Feet is always 36 inches, whether you’re gauging it with a tape measure, yardstick or laser-powered rangefinder. Ram may be a strong proponent of the J1995 procedure, but its rivals aren’t necessarily in agreement; they think their measuring techniques are more accurate.
“We’re using 1349 for our engines,” said Mike Levine, truck communications manager at Ford, a standard they believe is more rigorous than J1995.
Levine said, “If you look at the HD customer, about 90 percent of them tow … So they’re looking for great low-end torque and they’re looking for high efficiency with the power to pull a heavy trailer.”
Ford’s 6.7-liter Power Stroke diesel V8 puts out 440 horses and 860 lb-ft of torque. Levine was eager to point out that these are best-in-class standard numbers. In comparison, Ram’s Cummins is offered in three different potencies. With a manual gearbox, it’s rated at 350 hp and 660 lb-ft; when equipped with the 68RFE automatic transmission, those figures increase to 370 and 800; finally, when paired with an optional Aisin self-shifting gearbox, drivers get 385 ponies and the full 900 units of twist.
It’s worth noting that in 2015 model-year Rams, the Cummins inline-six is an $8,305 option. Beyond that, you have to spend an additional $2,995 for the Aisin automatic transmission.
But back to test procedures. When asked if there was any estimable percentage difference between J1995 and J1349, Pollak said, “There’s so many variables, so much involved, it would be hard to make any kind of comparison like that.” Unfortunately, there’s no real way to stack them against one another.
“Each of them are equally valid, equally fine,” noted Pollak. However, “Unless you go through our certified power program … we have no oversight,” so conceivably an automaker could make nearly any claim they wanted. “And that’s one of the reasons we started our certified power program,” added Pollak.
But where does General Motors, the third biggest player in the heavy-duty truck segment stand on this issue? According to Tom Read, the powertrain communications man at GM, all of their engines, unless otherwise noted, are rated using SAE J2723, a third procedure, which is arguably the most trustworthy one.
Explaining what this is, Pollak said the J2723 test “is our certified power program.” It involves lots of official paperwork as well as a specially trained, third party individual that verifies the procedure as well as the resultant horsepower and torque figures.
Curiously, SAE certification can be applied to either J1349 or J1995, a manufacturer simply has to follow the rules outlined in J2723. Confused by all of these numbers? Good. There are even more below ...