V8 for Jeep’s Most Powerful Wrangler

As the perfect antidote to growing government calls to ban ICE technology, Jeep has shoe-horned a whopping 6.4-liter gasoline V8 into the most powerful Wrangler it has ever produced.

As UK motorists balefully stare towards its government mandating of no ICE powertrains in new vehicles by the end of the decade, there’s the comforting knowledge that one of these last hurrahs for combustion technology should tide many of us through for the remainder of our driving lives. The 2021 Jeep Wrangler Rubicon 392 brings the sort of smile to the petrol-head’s face that only 466bhp and 470ft-lbs o

f torque can bring.

That muscle translates to a claimed 0-60mph sprint time of under 4.5 seconds although this will be less important to most SUV aficionados than its awe-inspiring ability to tackle the toughest of mountain trails. That’s because it boasts greater off-road capability with greater approach and departure angles, suspension articulation, maneuverability and water wading of up to 32-inches.

Also critical to performance off-road, there’s nearly 75% of the peak torque available from just above engine idle speed.  The performance of the V8 is based on a cast iron cylinder block and aluminum heads, accented with an active intake manifold, variable camshaft timing, twin spark plugs per cylinder, sodium-filled exhaust valves, hollow-stem intake valves and piston oil cooling jets. The Wrangler Rubicon 392 engine is fitted with a rear-sump oil pan, high-mount alternator and free-flowing exhaust manifolds.

There’s also fuel saver technology with cylinder deactivation that shifts to high-fuel-economy four-cylinder mode when engine loads are light, such as cruising on highways. A functional bonnet scoop feeds the engine with cool, denser, outside air, enhancing engine breathing and performance. There’s a ‘Hydro-Guide’ air intake system with a tri-level ducting system allowing a flow of 56-liters per minute away from the engine’s incoming air. This enables the Wrangler Rubicon 392 to wade through deep water even if a bow wave washes over the bonnet.

Should the bonnet scoop become restricted by snow, mud or debris, a secondary air path within the bonnet structure feeds the engine, making it possible for the car to reach top speed even with a fully blocked primary air path.

An active dual-mode exhaust engages automatically, opening valves in the pipe system under higher engine loads to reduce exhaust back pressure. The driver can also activate the system with the press of a button. The dual-pipe performance exhaust system is finished off with unique quad exhaust tailpipes.

Transmission

Its fully electronic, eight-speed automatic transmission features on-the-fly shift-map changing. System software relies on several input parameters to determine the appropriate driving conditions and adjusts shift patterns in response. The result is automatic shifting attuned to the performance requirements.

The powertrain calibration of the Wrangler Rubicon 392 includes Torque Reserve and AMax shifting, accessible when doing a drag-strip brake torque launch, that deliver maximum acceleration for solid-pavement launches. Torque Reserve manages fuel flow to the cylinders and controls spark advance or retard to balance engine rpm and torque. AMax shifting, a performance-enhancing strategy used on the Jeep Grand Cherokee Trackhawk, maximises forward torque by coordinating shift time and engine torque management.

The heart of the driveline is a Selec-Trac full-time, active transfer case with a 2.72:1 low-range gear ratio. The transfer case has four driver-selectable modes: 4WD Auto, 4WD High, Neutral, 4WD Low.

Naturally many chassis upgrades have also been made including frame rails, front upper control arms and cast iron steering knuckles, heavy-duty brakes, Dana 44 front and rear axles with thicker axle tubes and Tru-Lok electronic locking differentials. An electronic front sway-bar disconnect boosts the five-link front and rear suspension travel while the Wrangler Rubicon 392 comes with a 2-inch factory lift and is fitted with FOX aluminum monotube shock absorbers.

— Paul Myles is a seasoned automotive journalist based in London. Follow him on Twitter @Paulmyles_


Leave a comment

Your email address will not be published. Required fields are marked *