The quickest, most powerful Jeep vehicle ever
NASREC, Johannesburg – Jeep® vehicles are known worldwide for their capability, utility and distinctive style. The all-new Jeep Grand Cherokee SRT8 combines these qualities with Street and Racing Technology’s (SRT) balanced approach to performance, resulting in the quickest, most powerful Jeep vehicle ever created, and the ultimate performance sport-utility vehicle.
Powered by a 6,1l HEMI® V8 producing 313 kW and 569 Nm of torque, which adds 25 % more power than the 5,7l HEMI-equipped Jeep Grand Cherokee, the Jeep Grand Cherokee SRT8’s performance numbers include 0-100 km/h in less than 5 seconds, 0-160-0 km/h in the low 19-second range, and 100-0 km/h braking distance of less than 42 m.
To create the first SRT vehicle with full-time four-wheel drive, SRT engineers developed a drive system that was lightweight, yet robust and reliable enough to handle massive amounts of power and torque from the Jeep Grand Cherokee SRT8’s powertrain. One part of the equation was to create a new transfer case, combining housing components from two existing units with the upgrades needed to make it SRT-capable.
SRT engineers opted to use the front half of a Jeep transfer case chosen for its capability and light weight. It was mated to the rear half of a heavier-duty case, chosen for its ruggedness and ability to house the electronic full-time four-wheel-drive system components. The transfer case output shaft was upgraded to handle high torque generated by the SRT 6,1l HEMI.
The result is the Jeep Grand Cherokee SRT8’s unique transfer case, which provides the necessary power-handling capabilities for the Jeep Grand Cherokee SRT8 while weighing 27 kg less than a Jeep heavy-duty case.
Under normal driving conditions, 5 -10 % of torque is directed to the front wheels, but as much of the 6,1 l HEMI’s torque as needed can be directed forward when additional traction or stability is required. Remaining torque is sent via a heavy-duty driveshaft designed for the Jeep Grand Cherokee diesel model, to a Dana 44 rear differential upgraded with a larger ring gear within a new axle housing.
Providing power and torque to the unique SRT four-wheel-drive system is a specially tuned version of the new 6,1 l SRT HEMI engine. Inspired by the original family of HEMI engines, the SRT 6,1l HEMI employs its namesake hemispherical combustion chambers that provide power and efficiency, while retaining classic HEMI visual cues, including the orange-painted cylinder block and black valve covers.
SRT engineers who developed the Jeep Grand Cherokee SRT8’s engine achieved more power by adding more cubic capacity, increasing the compression ratio, and redesigning the cylinder head, intake and exhaust systems for better flow and increased engine speed.
For more displacement, SRT engineers bored out the diameter of the cylinders in the HEMI by 3,5 mm each in order to increase the total displacement from 5,7l to 6,1l.
Compression ratio was also increased to 10,3:1 from 9,6:1, increasing engine efficiency and power. Engine breathing was increased with new higher-flow cylinder heads, a specially designed intake manifold and fresh air induction system, and exhaust headers with individual tubes encased in a stainless steel shell.
All are unique to the 6,1l HEMI engine. Larger-diameter valves and reshaped ports in the heads allow for maximised air flow. The intake manifold was designed with larger-diameter and shorter runners for higher-speed tuning. Exhaust is routed through a large-diameter exhaust system with four-inch chrome tips.
To further increase power, performance-oriented camshaft profiles were developed to allow more air in and out of the cylinders, as well as managing a higher engine speed. SRT engineers increased the HEMI’s peak power output engine speed by nearly 20 % to 6 000 r/min. Intake and exhaust valve stems are hollow, and are filled with sodium to help dissipate heat more efficiently.
The high-performance SRT 6,1l HEMI is strengthened with redesigned components, including a reinforced engine block, forged steel crankshaft, high-strength connecting rods, floating-pin pistons (cooled by oil squirters), and an oil pan modified to manage oil return to the pan sump at high engine speeds.
Power from the SRT 6,1l HEMI is sent through a special torque converter to an SRT-upgraded five-speed automatic transmission. Torque is then sent to front and rear differentials through a specially designed transfer case.
Ride and handling
The Jeep Grand Cherokee SRT8 is endowed with the signature SRT characteristic of world-class ride and handling across a dynamic range.
Chassis setup is aimed at balanced performance with SRT-tuned dampers, unique sway bars and specially tailored spring rates and suspension bushings. New front suspension knuckles feature a camber angle calibrated for optimum suspension performance.
The ride height of the Jeep Grand Cherokee SRT8 is lower than the Jeep Grand Cherokee, which lowers aerodynamic drag as well as the centre of gravity, and contributes to the vehicle’s stability and aggressive stance.
To meet or exceed handling and safety criteria, the Electronic Stability Program (ESP) was specially calibrated for the Jeep Grand Cherokee SRT8.
Further contributing to its aggressive stance, the Jeep Grand Cherokee SRT8 is fitted with unique forged 20-inch five-spoke aluminum wheels shod with high-performance tyres with dimensions are 255/45/20 in the front and rear, which also contribute to the Jeep Grand Cherokee SRT8’s stability.
The braking system of the Jeep Grand Cherokee SRT8 is designed to provide outstanding capability as a counterpoint to the vehicle’s awesome launch and acceleration.
All four wheels feature four-piston performance brake calipers developed by Brembo, finished in gloss black. While braking, these calipers clamp down on 360 x 32 mm vented discs up front, with 350 x 28 mm vented discs at the rear.
SRT’s credo demands functional exterior enhancements that contribute to performance and resonate with the brand character. The Jeep Grand Cherokee SRT8’s lowered, aggressive stance shows its unmistakable Jeep identity endowed with SRT DNA.
An all-new front fascia makes use of aero improvements to reduce lift and drag, while providing sufficient air flow to cool the 6,1l HEMI engine. The front fascia also helps increase brake-system cooling through integrated air ducts.
In the rear, an all-new fascia incorporates an aggressive centre cut out to accommodate dual four-inch exhaust tips.
Another functional enhancement is sill extensions, which help create downforce.
The Jeep Grand Cherokee SRT8 cabin is distinguished by power-adjustable, deeply sculpted performance front seats complete with uniquely patterned performance suede inserts to hold occupants during aggressive maneuvering.
Interior accents include a “carbon-fiber” technical finish on the leather-wrapped steering wheel, instrument-panel brow and shift knob, complemented by a “refined aluminum” finishing on the centre stack, shifter and door-switch bezels.
Full instrumentation includes a 300 km/h speedometer, tachometer and temperature gauges, all trimmed with a unique blue accent and located within a carbon fiber-trimmed binnacle. Oil pressure and temperature may be monitored through a specially configured display unit centrally located in the instrument panel.