Ram Trucks heralded the arrival of its newest engine, the 3.0-liter Hurricane High Output straight six, with the promise of more power, more performance, and more efficiency. High-octane fans were skeptical. They likely have been hoping for a Hellcat, not what they perceived as a housecat, for the newest Ram.
At the top of the current heap of Ram 1500 trims is the RHO, a 540-horsepower truck that’s equally capable of hauling two-by-fours and catching air launching off a desert hill. The first reviews of the RHO are out, and it turns out this kitty has claws.
I put the truck and its new engine to the test as a competitor in the Rebelle Rally, driving it hard in the sand, dirt, rocky trails, and silt of the California and Nevada desert for eight days straight. In every instance, the RHO exhibited plenty of oomph with zero disappointment and certainly better fuel efficiency than the previous V8-powered TRX trim. Here’s how the engineers made it happen.
Hurricane-force turbo
With two fewer cylinders than Ram’s now-discontinued fire-breathing TRX, the RHO is lighter on its feet than the T. Rex. Doug Killian, Chief Vehicle Synthesis Manager for Ram, told Popular Science that the team started with the recipe for TRX and riffed from there.
“The RHO chassis does share some fundamental points with TRX,” Killian says. “It’s still fundamentally the TRX chassis in terms of hard points and components.”
That said, the RHO has its own personality, making it a dynamic performer in the desert that competes with Ford’s F-150 Raptor. Drivers will feel the difference between the Hellcat and the Hurricane in its weight balance. The RHO is 150 pounds slimmer than the TRX, and its weight is distributed differently: the RHO is 180 lighter in the front and 30 pounds heavier in the back, Killian says. As a result, the newest truck is quicker in the turns and more nimble.
“The truck is more tossable,” Killian says. “It’s easier to set up into a drift. The turn in is quicker, allowing for transitions faster on a dirt track. It’s more fun in those environments because it’s easier to get sideways.”
That’s due in large part to the size of the engine. The engine block itself is smaller, and it’s made from cast aluminum instead of iron, Killian explains. And, of course, the layout as a straight-six versus a V8 makes room for the dual turbochargers to improve efficiency. Each high-flow turbocharger forces air into three cylinders and the system works together as one for the best throttle response. Opting for smaller, 54-millimeter turbos instead of one larger turbo means less inertia, which translates to turbo lag reduction.
Software-tuned drive modes
A meeting with Stellantis High-performance Off-road Vehicle Development and Validation Engineer Toon Tan proved helpful to run the RHO at its optimum capability. While the pickup comes with nine modes (Auto, Tow, Mud/Sand, Rock, Snow, Sport, Baja, Custom, and Valet) Tan told me the truck was engineered to read the terrain, and even newbie off-roaders could run it in Auto mode most of the time.
It’s true that on fairly consistent surfaces, I could almost hear the truck thinking and adjusting accordingly. However, I found that selecting the Mud/Sand mode, turning off traction control and stability control, and running the RHO in four-wheel high gave me the best results when scaling dunes in southwest California. Every once in a while, I’d choose Baja mode, which sends 75 percent of available torque to the rear, giving the truck better grip on loose surfaces.
During development, the engineering team used a repeatable place to test, much like sports cars are proven in hot laps on a track, Killian says. But instead, the track is dirt and sand. Engineers were busy adjusting code, not tweaking the mechanics in this modern truck. Measuring lap times, corner exit speeds, and driver feedback on throttle responsiveness told the team when they found the optimal recipe.
“We’re exercising the drive modes differently,” Killian told me. “It’s essentially an engineer calibrating on a laptop interfacing with our control system. It’s not mechanical; it’s more an electronic calibration exercise.”
The RHO represents a unique slot in the sport truck segment. It’s different from Ram’s brawny Rebel trim, and it’s not a TRX. So ignore the horsepower statistics and focus on its holistic performance, Killian says.
“The RHO brings its own high-performance off-road driving experience and it fits that niche really well,” he asserts. “It’s not just the numbers; it’s when you feel these things together. We’ve hit a real resonant note here.”
After eight days on tough trails and slippery sand, the RHO prevailed with some desert striping on the paint but no worse for the wear. This twin-turbo truck is an absolute blast.
Source link
