Review: Jeep Wrangler Rubicon 392 – power meets off-road prowess
We’ve driven our share of muscular off-road machines. From the Ford Raptor to the uber-lush G Wagen and the Ram TRX, it’s all been fun. So what's next? How does a Jeep Wrangler Rubicon with a 6.4-liter monster under its hood sound?
At a glance
- Huge power from the big 6.4L engine
- Lots of changes to accommodate that power
- Missing suspension and braking tune for the muscle
- Pricey, but worth it compared to an aftermarket swap
Jeep, Dodge, and Ram have long been buddies, and now that Dodge is willing to shove huge 6.4-liter V8s into anything with wheels, it was only a matter of time before the other two got the SRT treatment. With Ram, it was the T-Rex pickup. With Jeep? The Wrangler Rubicon 392.
On its surface, this is just a Wrangler Unlimited with the Rubicon package into which a 6.4-liter V8 and power exhaust have been inserted. There’s more going on than that, though – a vehicle capable of taking an engine’s torque and converting it to 72:1 at the wheel is going to need some adjustments when that engine’s torque nearly doubles.
Yep. The Wrangler 392’s V8 outputs 470 horsepower and 470 pound-feet of torque (350.5 kW, 637.2 Nm). To account for this amount of power going to the wheels, Jeep changed out the Wrangler Rubicon’s ... well, almost everything.
The engine mounts to an eight-speed automatic transmission and full-time, active transfer case. That case has low-range gearing at 2.72:1 and is, as implied, engaged full time. Most of the time, driving will have the transfer case’s shifter in 4 Auto, which defaults to a 30:70 front:rear torque split for the axles. In 4 Part-Time mode, that split becomes 50:50, but biases towards front axle power in traction control.
Many parts of the 392 are taken from other models in the family. The engine and transmission, for example, are very similar to what’s in the Dodge Durango SRT. The Dana 44 front axle with its bigger brakes, thicker tubing, and cast-iron knuckles is straight off the Gladiator Mojave model. The Dana 44 rear axle is identical to the larger-braked version found on the electric Wrangler 4xe. Final drive gearing is 3.73:1 and includes mechanical lockers on both axles.
Going with those additions, Jeep also stiffened the framing with strategically placed stiffeners, changed the front crossmember to accommodate the larger crank pulley of the V8, and used stiffer engine mounts for the bigger block. To fit the engine itself, the Wrangler’s body had to be raised another inch so it would clear the engine and transmission’s bulk.
Since the big, throaty V8 is also thirsty for air (and fuel), Jeep made modifications to the Wrangler 392’s intakes. The hood, while definitely a Wrangler clamshell, has a lot of Dodge Hellcat in its look, with a bigger top intake and a big hump in the middle for extra supercharger clearance. That hump has "392" emblazoned on either side. Some secondary intake ports for backup and airflow allowance are also seen. Golden tow hooks, black leather for the interior, and some other cosmetic details finish detailing this as a special sort of Jeep.
One thing Jeep missed, we noted, was suspension tuning. The front end of the Wrangler 392 is heavy, and the suspension bottoms out in hard off-road driving much quicker than does the same setup on the Wrangler Rubicon with its standard V6 engine. That tendency to thump, and the off-putting forward jerk it creates, takes some getting used to. Some of this is due to the changes at the rear, where Jeep moved the rear suspension pieces an inch away (one inch down for lowers, one inch up for uppers) and then restricted jounce travel by two inches to compensate.
Front springs were increased by 10 percent, but the rear was dropped by 20. The rear roll bar was made stiffer in order to compensate and stiffen the chassis at the back. The Tennoco monotubes that come with the standard Rubicon package were swapped for monotube Fox 2.0 shock absorbers, which we think was a mistake. Fox 2.5’s with a reservoir would have been far better, considering the weight of this setup.
Jeep also seemed to think of braking as an afterthought with this rig. While the brakes are beefier, thanks to those axle changes, it still takes a lot of time – we mean a lot of time – for the Wrangler 392 to stop after hitting its 100.5 mph (161.7 km/h) speed limiter. It hits that speed limit in about nine seconds, by the way. So long as there is plenty of space to stop after doing 13-second quarter mile sprints, the 2021 Wrangler Unlimited Rubicon 392 is a blast to drag. Especially in the dirt. Oh, and you’ll have to supply your own launch control. It doesn’t come with that. Use your feet.
Instead, the Jeep Wrangler 392 comes with the same crazy good off-road capability as its other Rubicon brethren. It’s most comfortable in dirt, on rocks, and fording through streams. On pavement? Not so much. As the popular Jeep saying goes, "It’s an off-roader first, a highway driver ... maybe fifth." The gist? Don’t go trying to race track the Wrangler 392. You will flip it over.
Off the pavement, though, we had a wonderful time in the 392. It’s a beautiful machine for traversing our favorite harsh terrain and it reminds us, as is expected of a Wrangler Rubicon, why those harsh paths through the wilderness are called "Jeep Trails" in the vernacular.
In the end, the 2021 Jeep Wrangler 392 isn’t for everyone. Or even most. It’s for enthusiasts who love the sound of a throaty V8, want all of the power in the world at their command at any time, and who love high-speed off-road travel. The muscle of the V8 is great when tackling harsh terrain, but requires some nuance and control at slow speeds.
Pricing for the 2021 Jeep Wrangler Unlimited Rubicon 392 starts at US$74,995. That’s steep, but not when you consider what it costs to do an aftermarket swap with a 6.4L crate engine.
Product Page: 2021 Jeep Wrangler Unlimited Rubicon 392
Please keep comments to less than 150 words. No abusive material or spam will be published.