Jeep Grand Cherokee SRT8: First Look

By Motoring Channel Staff - 25/Aug/2006

Melbourne, Australia — The Porsche Cayenne Turbo may be experiencing anxiety attacks with the launch of the super quick SRT8 Grand Cherokee from jeep: "It has the raw power to out-perform the likes of a Porsche Cayenne Turbo at a fraction of the price," says Chrysler Australia's chief, Gerry Jenkins.

Priced at $85,990, you get a lot of 4x4 for the money, as it comes standard with things like dual zone automatic temperature control, leather interior, rear park assist system, rain-sensing wipers, a powerful Boston Acoustics CD stereo system plus huge 20-inch wheels and electronic stability control (ESP).

And for those drivers that would love to own what is allegedly the quickest production SUV on the market, the 6.1-litre Hemi V8 engine produces an earth-splitting 569Nm of torque. That's even more torque than HSV's new GTS, which is powered by a high performance 6.0-litre V8.

Chrysler hasn't provided a precise 0-100km/h time, but suggests that the low 5 second range is about right. We are predicting a 5.1 second 0-100km/h time, which would make the 4WD one of the fastest in the world, as the recently revised Porsche Cayenne Turbo S with completes the sprint in 5.2 seconds.

"When Jeep set out to create its quickest-ever model, it was with the race track rather than the mud track in mind," said Gerry Jenkins, the main man at Chrysler Group Australia.

"The SRT8 is not intended to be off-road capable. Instead, with this injection of SRT DNA, the new Grand Cherokee SRT8 establishes a fresh benchmark for high-performance SUVs. It has the raw power to out-perform the likes of a Porsche Cayenne Turbo at a fraction of the price. At just $85,990 it leaves in its dust competitors that cost twice as much.

"With the SRT8's addition to the Grand Cherokee line-up we now offer a broad range of engines to suit our customers desires including the highly efficient 3.0-litre turbo diesel powertrain," said Jenkins.

Despite it's heavy 2,270kg dry weight (that will rise to around 2500kg with passengers and fuel) Jeep's hulking new Grand Cherokee is such a quick vehicle because of its 4x4 traction system, which the company says was designed maximise the traction available to the driver, while being robust and reliable enough to handle the engine's mammoth torque generation.

As Jeep explains, an all-new transfer case is set up to deliver from five to 10% of torque to the front wheels in normal driving conditions, with the remaining 90-95% being sent to the rear axle fitted with a Dana 44 rear differential. But when driving on slippery surfaces, the four-wheel drive system can automatically transfer up to 100% of torque to the front wheels when additional traction and stability is required. The gearbox is a heavy-duty 5-speed automatic.

Augmenting the revised four-wheel drive system, the suspension is not of the typical 4x4 mould. Because the American company has built the Grand Cherokee SRT8 as a road-going performance vehicle, it features a suspension package more suited to sealed roads instead of being able to climb over large obstacles. The suspension layout, as Jeep explains, uses the same system from the normal Grand Cherokee (independent double wishbones at the front, live rear axle) and gets new Bilstein dampers, stiffer spring rates and larger-diameter anti-roll bars.

The hard hitting SRT8's ride height has been dropped by 25mm to reduce drag and lower the CoG to improve stability and handling. The dropped height also gives the vehicle a sporty image when paired with the vehicles 20-inch wheels, which are fitted with 245/45 ZR20 tyres. Other changes to the car's chassis include a modified electronic stability program (ESP) and more responsive steering - now taking 2.85 turns lock-to-lock, compared with 3.14 turns on the normal Grand Cherokee.

To deal with the vehicle's immense power and weight, the brakes went under intense scrutiny and have been upgraded to provide a potent counterpoint to the vehicle's unbelievable accelerating performance. Brembo was the only brake maker to offer kind of stopping power needed, and Jeep chose racing-style calipers equipped with four pistons working 360 x 32mm ventilated discs at the front axle, with 350 x 28mm ventilated discs for the rear.

Jeep's muscled-up new Grand Cherokee is equipped with the kind of chassis you'd expect on a sports coupe, and the engine is also reflective of the vehicle's aggressive attitude. Under the hood of the flying brick is an SRT 6.1-litre Hemi V8 engine generating 73kW more than the 5.7-litre version. The 90° V8 has two valves-per-cylinder (one intake, one exhaust) and like it's historical cousins from the '60s and '70s, the new engine makes use of hemispherical combustion chambers that provide a positive environment for burning fuel. Vitals statistics are as follows:

Power: 313kW @ 6000rpm
Torque: 569Nm @ 4800rpm
0-100km/h: "Low 5s"
Top Speed: 245km/h

The Chrysler SRT engine features an orange-painted cylinder block and black valve covers, and compared to the 5.7-litre Hemi V8 it gets redesigned the cylinder head, raised compression ratio, increased capacity, and reinforced internal components (forged steel crankshaft, connecting rods, engine block) to allow higher engine speeds. The bigger 6063cc displacement results from increasing cylinder bore by 3.5mm, and Jeep says that a special intake manifold was designed with larger diameter runners for higher-speed tuning, and that the exhaust 'header' pipes have individual tubes encased in a stainless steel shell, all of which are routed through a larger-diameter (70mm vs 63.5mm) exhaust system with 101mm chrome tail pipes that are mounted centrally in a Dodge Viper tribute.

The big V8's 313kW of power is channelled through an A580 5-speed automatic transmission, allowing drivers to switch to a tiptronic mode for semi-auto gear selection. The combined city/highway cycle fuel efficiency is horrendous: 16.4L/100km, and it produces 388g/kg of C02. 

Chrysler and Jeep's SRT brand is like Holden's HSV or Ford's FPV, and befitting a car of such status it gets a number of external styling cues that communicate its sporting potential. As well as the 25mm lowered ride height, the hardcore Grand Cherokee features SRT8 badging on its flanks and rear end, and a new front bumper section that has larger openings to provide more air to the engine, and Jeep claims it reduces lift and drag as well. The rear end bumper is also new, with integrated central exhaust outlets measuring an attention-grabbing 101mm in diameter.

Jeep will offer the hefty Hemi in three colours, black, silver, or blue, and gives the interior a sporty treatment too. As the American automaker explains, the driver and front passenger get deeply sculpted performance heated front seats with power-adjustability and medium slate grey leather/suede trim. Aluminium accents dot the cabin and a 300km/h speedometer is kept company by tachometer and engine temp gauges, with blue highlights. A 6-disc CD changer with a 276 Watt stereo system powers a Boston Acoustics 6-speaker speaker system, with steering wheel-mounted controls, while rain sensitive automatic windscreen wipers and climate control air conditioning are also standard features. The only optional extra is a sunroof, which adds $3,191 to the car's $85,990 price tag.

Jeep has boosted the performance vehicle's safety systems, adding a revised ESP system, side curtain airbags, ABS, BA, rear parking assist and a Thatcham 1 alarm and immobiliser.

The Grand Cherokee SRT8 marks the third SRT entrant into the Australian new car marketplace as it joins the Chrysler Crossfire SRT6 and 300C SRT8. Only about 50 units will make their way to Oz, on sale from late August 2006. Gerry Jenkins added: "If driving enthusiasts want to get their hands on the fastest Jeep ever they will have to be as quick as the car itself! Less than 60 examples will be brought into Australia this year."