If there is one vehicle that combines all the SRT product development traits and pushes them to the extreme, it’s the 2006 Viper SRT10 Coupe. The process of developing the Viper Coupe started nearly two years ago, when engineers approached Knott with a full business case for the vehicle. Seeing their plan as too expensive, Knott ordered his team to trim costs by 25%, through the use of Kirksite tooling, which resulted in a production vehicle that maintains the Viper GTS tradition, within the original budget. Knott team also used the existing platform from the Viper roadster, along with the doors and front end from the ragtop version. Among the only unique parts are the door glass, the hardtop, rear quarter panels and decklid. Styling-wise, the coupe features a number of unique touches, including the shadowing of the rear tail lamps, ala the 2000 Viper GTS/R concept vehicle. “That’s one of my favorite parts of the car,” Knott says as he points to the rear fascia. “Frankly, this is the kind of thing we do as a company that others don’t have the guts to do.” The SRT team gave Viper owners a sneak-peek at the production coupe last year, and they requested some modifications, including more pronounced rear cheeks and aggressive rear glass profile. Engineers listened and increased the cheeks by 15 mm and moved the rear glass back an additional 3 in. The double-bubble roof, made to accommodate the extra clearance of racing helmets, also returns. The coupe variant manages to increase stiffness by 30%, while rear down force has been improved by an equal margin. Like its open-top sibling, the Viper Coupe is powered by the renowned 8.3-liter 10-cylinder engine, producing 500-hp and 525 lb.-ft. of torque. Chrysler claims the Viper Coupe can move from 0-60 mph in less than 4 seconds, with braking from 60-0 mph done in less than 100 feet (thanks to the four-piston fixed caliper Brembos), with 0-100-0 mph achieved in the low 12 second range.
The most controversial of the new models is the Grand Cherokee SRT8, which seems to be a radical departure from what Jeep has traditionally stood for: rugged, off-road prowess. This version is a complete 180 from tradition, as its 420-hp, 6.1-liter HEMI V-8 and 1-in. lower ride height, attest. This doesn’t mean the Grand Cherokee has lost all of its Jeep credibility. SRT engineers managed to develop a full-time four-wheel drive system for the Grand Cherokee SRT8 capable of handling the massive 420 lb.-ft. of torque produced by the HEMI at 4,800 rpm. Engineers combined the front half of a traditional Jeep transfer case with the rear of a heavy-duty case, while at the same time upgrading the transfer case output shaft to handle the higher torque. “We took a light-weight front end transfer case…and the reason why we did that we are not driving as much torque through the front, so we didn’t need that increased weight there or cost. Then we took a heavy-duty rear end transfer case and we mated the two together,” says SRT boss Dan Knott. A side benefit was generated by marrying the two: the new case weighs 60-lb. lighter than Jeep’s traditional heavy-duty unit. The transfer case features a full electronically controlled wet clutch, which takes into account feedback from the vehicle angle, lateral g, throttle angle, and steering wheel position sensors and calculates the exact amount of torque transfer necessary to keep the Grand Cherokee firmly planted. The infinitely variable set-up enables up to 100% of the power to be transferred between the front and rear axles. To depart from its more pedestrian stable mate, stylists worked with the engineering team to revise the front fascia to reduce lift and drag, while at the same time providing efficient airflow to the Brembo brakes. The rear fascia features bad-ass center-mounted dual 4-in. exhaust tips. Knott says the SRT team is looking at providing Chrysler’s acclaimed multiple displacement cylinder-deactivation system (MDS) found on the 5.7-liter HEMI on future SRT models, although the current 6.1-liter version will not accommodate the technology due to its cam lift profile, which he claims is too high. Once engineers can make MDS work with the 6.1-liter, it will help the Grand Cherokee avoid the gas guzzler tax.
KNOTT ON THE VETTE
Chevrolet has introduced its own Viper-fighter with the ’06 Corvette Z06, which has the Viper bested in the power race by 5 horsepower, while the ‘Vette wins big in the weight category, coming in 320 lbs. lighter than the Viper. Knott gives tongue-in-cheek compliments to the Chevy team: “They have got a really sweet performing car and I take nothing away from those guys. It took them 15 years to match the Viper and they’re pretty close now. But the Viper has a different character: it is a back-to-basics, make-no-excuses, in-your-face, gut-wrenching torque, all-American sports car and you won’t find cupholders and you won’t find fancy interiors, you will find basic performance.”
What would the world do without a SRT version of the Charger? That’s what Knott’s team asked themselves. Knott says the team thought they would be labeled “insane” if they did not inject SRT DNA into Dodge’s most infamous muscle car moniker. They started by adding a hood scoop, along with front fascia upgrades, including integrated air ducts to direct air to the brakes, as well as an air dam to reduce lift. The hood scoop does not perform a traditional ram air function because of the HEMI’s airflow arrangement. “If we would have done it, we would have had to reverse the airflow, which would have lost us a lot of horsepower and torque,” Knott says. Changes also were made to the Charger’s rear fascia, most notably larger 3.5-in. dual exhaust tips. The Charger shares the 425-hp, 6.1-liter HEMI engine found in the Chrysler 300C SRT8 and Dodge Magnum SRT8, which moves this 4,180-lb. sedan from 0-60 mph in the low 5-second range and from 0-100-0 mph in just under 17 seconds. Engineers also revamped the Charger SRT8’s electronic stability program (ESP) to include three settings: full ESP, partial ESP and ESP off, making the Charger the first SRT vehicle to enable full disengagement of the ESP system. The Charger’s transmission features a revised AutoStick mode, which holds gears longer for added performance. Attention was also paid to the Charger SRT8’s exhaust note, which produces a growl that will intimidate just about any hot-rodder. The only downfall remains the Charger’s interior, which lacks any sort of character and is the same as that found on the Dodge Magnum. This is the single area where the Charger seems to truly lack its own identity. But the Charger scores big-time in the bang-for-the-buck quotient, since the car carries a base price of $34,995.