Jeep has introduced its new Grand Cherokee SRT8, powered by a 6.1-litre SRT Hemi V8 engine that propels the big Jeep to 60mph in under 5 seconds.

That’s quicker than a Porsche Cayenne Turbo or BMW X5, and is Jeep’s fastest and most-powerful model ever produced.

“Jeep vehicles lead the way in performance and versatility,” said Jeff Bell, Vice President, Jeep, Chrysler Group. “The all-new 2006 Jeep Grand Cherokee SRT8 adds a new dimension to performance and versatility – and value. With its SRT-engineered 6.1-litre HEMI® engine and specially developed full-time four-wheel drive system, the 2006 Jeep Grand Cherokee SRT8 provides stunning performance in an amazing variety of driving conditions.

“The all-new 2006 Jeep Grand Cherokee SRT8 marries Jeep capability with SRT performance to create a vehicle that will leave in its dust competitors that cost twice the price,” Bell added.

Powered by a 6.1-litre HEMI producing 415 horsepower (85 more horses and 25 percent more power than the US-only 5.7-litre HEMI-equipped 2006 Jeep Grand Cherokee) and 410 lb.-ft. of torque, the all-new 2006 Jeep Grand Cherokee SRT8’s performance numbers include 0-60 mph in under 5 seconds, 0-100-0 mph in the low 19-second range, and 60-0 mph braking distance of approximately 125 feet.

“When we set out to create the first Jeep-branded SRT vehicle, the 2006 Jeep Grand Cherokee presented us with an incredibly capable starting point,” said Dan Knott, Director – Street and Racing Technology, Chrysler Group. “With an infusion of SRT DNA, the 2006 Jeep Grand Cherokee SRT8 is the new benchmark performance SUV. It has the raw power to outperform the Porsche Cayenne Turbo, while providing exceptional ride and handling, world-class braking, race-inspired interior appointments and functional, performance-oriented exterior enhancements.”

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 horsepower and torque from the 2006 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 6.1-litre HEMI.

The result is the all-new 2006 Jeep Grand Cherokee SRT8’s unique transfer case, which provides the necessary power-handling capabilities for the Grand Cherokee SRT8 while weighing 60 pounds less than a Jeep heavy-duty case.

Under normal driving conditions, from 5 percent to 10 percent of torque is directed to the front wheels, but as much of the 6.1-litre 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 European Jeep Grand Cherokee diesel model, to a Dana 44 rear differential upgraded with a larger ring gear within a new axle housing.

“We wanted the acceleration that only four-wheel-drive can provide,” said Knott. “Our goal for the 2006 Jeep Grand Cherokee SRT8 was to have a well-balanced vehicle with a high fun-to-drive quotient. The SRT-developed electronic four-wheel drive system is perfectly suited to this.”

Providing horsepower and torque to the unique SRT four-wheel drive system is a specially tuned version of the new 6.1-litre SRT HEMI engine. Inspired by the original family of HEMIs, the SRT 6.1-litre HEMI employs the 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.

With the Chrysler Group’s clean and efficient 5.7-litre HEMI as a starting point, SRT powertrain engineers developed 85 more horsepower over the Jeep Grand Cherokee’s 5.7-litre HEMI by adding more cubic inches, increasing the compression ratio, redesigning the cylinder head, intake and exhaust systems for increased flow, and increasing engine speed.

For more displacement, SRT engineers bored out the diameter of the cylinders in the HEMI by 3.5 millimetres each in order to increase the total displacement to 6.1 litres from 5.7 litres.  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 (which allows water-fording capability of up to 19 inches), and exhaust headers with individual tubes encased in a stainless steel shell. All are unique to the 6.1-litre 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 (2.75-inch vs. 2.5-inch) exhaust system with 4-inch chrome tips.

To further increase horsepower, performance-oriented camshaft profiles were developed to allow more air in and out of the cylinders, as well as manage a higher engine speed. SRT engineers increased the HEMI’s peak power output engine speed nearly 20 percent to 6,000 revolutions per minute (rpm) from 5,000 rpm. Intake and exhaust valve stems are hollow, and the exhaust valve stems are filled with sodium to help dissipate heat more efficiently.

The high-performance SRT 6.1-litre HEMI is strengthened with redesigned components, including a reinforced engine block, forged steel crankshaft, high-strength powdered-metal 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 6.1-litre HEMI is sent through a special torque converter to an SRT-upgraded A580 five-speed automatic transmission. Torque is then sent to front and rear differentials through a specially designed transfer case.

The all-new 2006 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 2006 Jeep Grand Cherokee SRT8 is one inch lower than the Jeep Grand Cherokee, which lowers aerodynamic drag and contributes to the vehicle’s aggressive stance.

To meet or exceed handling and safety criteria, the Electronic Stability Program (ESP) was specially calibrated for the 2006 Jeep Grand Cherokee SRT8.

Further contributing to its aggressive stance, the all-new 2006 Jeep Grand Cherokee SRT8 is fitted with unique forged 20-inch five-spoke aluminium wheels shod with high-performance Goodyear W-rated four-season tires with run-flat capability. Tire dimensions are 255/45/20 in the front, and a massive 285/40/20 in the rear.

With an optional hitch package available from Mopar, the all-new 2006 Jeep Grand Cherokee SRT8 is capable of towing up to 3,500 pounds.

The braking system of the all-new 2006 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. Under braking, these calipers clamp down on 360 x 32mm vented rotors up front, with 350 x 28mm vented rotors in the rear.

SRT’s credo demands functional exterior enhancements that contribute to performance and resonate with the brand character. The all-new 2006 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 6.1-litre 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 cutout to accommodate dual 4-inch exhaust tips.

Another functional enhancement is sill extensions to help create downforce. The roof rack available on the Jeep Grand Cherokee is not available on the all-new 2006 Jeep Grand Cherokee SRT8.

Three exterior colours are available: Bright Silver, Brilliant Black and Inferno Red.

The all-new 2006 Jeep Grand Cherokee SRT8 cabin is distinguished by power-adjustable, deeply sculpted performance seats in the front complete with uniquely patterned performance suede inserts to hold occupants during aggressive manoeuvring.

Interior accents include a “carbon-fibre” technical finish on the leather-wrapped steering wheel, instrument-panel brow and shift knob, complemented by a “refined aluminium” finishing on the centre stack, shifter and door-switch bezels.

Full instrumentation includes a 180-mph (300 kph) speedometer, tachometer and temperature gauges, all trimmed with a unique blue accent and located within a carbon fibre-trimmed binnacle. Oil pressure and temperature may be monitored through a specially configured display unit centrally located in the instrument panel.

Available options on the 2006 Jeep Grand Cherokee SRT8 include a DVD-based Navigation system with turn-by directions and voice prompts, SIRIUS® Satellite Radio and a UConnect? hands-free communications system with Bluetooth? technology. This system recognises up to seven different Bluetooth-equipped cellular phones and responds to voice commands, utilising a microphone in the rear-view mirror and the stereo system’s speakers for hands-free conversations.

The all-new 2006 Jeep Grand Cherokee SRT8 interior is offered in Medium Slate.

No official word yet on whether the SRT8 will make it to the UK.