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Here's what it'll take to build a Jeep Grand Cherokee Hellcat

Let's get one thing straight: We want a 707-horsepower Grand Cherokee Hellcat to happen. Badly. The latest report from Motor Authority is encouraging; the bonkers SUV supposedly has a codename, Project K, and has been given the green light for production. Fingers crossed. You might be wondering why the Trackhawk isn't already a thing. Hellcat engines exist, SRT Grand Cherokees exist, so just combine the two, right? It's not quite that easy. Here, we outline what needs to happen, why it should be the quickest Hellcat vehicle out there, and why it won't come anywhere near 200 miles per hour. How To Build A Hellcat Jeep The first engineering problem is feeding the air-intensive beast that is the 6.2-liter supercharged V8. The first engineering problem is feeding the air-intensive beast that is the 6.2-liter supercharged Hellcat V8. Breathing is important on two counts: pulling in enough air for the combustion to put out 707 hp, and then cooling the various heat exchangers once the engine is up to temperature. Dodge did it with the Charger and Challenger, it can do it with the Jeep. This is one place where the Grand Cherokee's larger frontal area might be a boon, as it gives the engineers more surfaces through which to suck air. Once you generate the 707 horsepower and 650 pound-feet of torque, it has to get to the wheels somehow. Jeep's current SRT all-wheel-drive system will at least need some beefing up to handle the torque. It could require a more complete re-engineering. We at least know the ZF-supplied eight-speed auto, used in the Dodge Hellcat models, is up to the task. The Hellcat engine should fit in the Grand Cherokee, as it's about the same size as the 6.4-liter currently in SRT Jeeps, but the Hellcat is taller because of its supercharger. The hood may need to be raised or at least resculpted for clearance, as well as to address those cooling needs. Quicker Than Everything, But Not Faster 200 mph? We're skeptical, from both a physics standpoint and a legal one. A reminder of the quick/fast distinction: quick is acceleration, fast is road speed. The Jeep's all-wheel drive will help put the Hellcat engine's power to the ground in a more manageable way than the Charger and Challenger do through just the rear wheels. That means better acceleration times than the Dodges (11.0 seconds in the quarter-mile for the Charger Hellcat, 11.2 for its Challenger sibling).

Watch this 650-hp Hennessey Jeep Grand Cherokee go from 0-60 in 3.9 seconds

Hennessey Performance Engineering has created an HPE650 package for the Jeep Grand Cherokee SRT fitted with the 6.4-liter Hemi engine. When it leaves the showroom floor it has 470 horsepower and gets from 0-60 miles per hour in 4.8 seconds. When it leaves Hennessey's garage floor after the upgrade it has 650 horsepower - 530 hp at the wheels, according to Hennessey - and gets to 60 mph in 3.9 seconds on its way to running the quarter-mile in 12.6 seconds.
There's more than just a Roots-type supercharger bolt-on, with ported cylinder heads and high-flow headers among the many changes made to the engine. You can watch this pre-2014 facelift silver model prove its spec sheet on the drag strip in the video below.

Chrysler says its 8-speed transmissions will save 700 million gallons

Chrysler Group's TorqueFlite eight-speed transmission could be earning some serious green bragging rights if the company's projections are correct. The recently widely proliferated automatic gearbox, which is now in more than a million vehicles around the world, is poised to save drivers an estimated 700+ million gallons of fuel over the vehicles' lifetimes (an expected cost savings of $2.5 billion). In addition, Chrysler expects a reduction in CO2 emissions by more than six million metric tons. According to Chrysler, and depending on the vehicle, the TorqueFlite can improve fuel economy. The TorqueFlite autobox features particularly close ratios from fifth to eighth gear (see the press release below for the specific numbers), and uses low-viscosity fluid that doesn't need to be replaced. Transmission software adapts to the driving situation to optimize efficiency based on driver behavior, temperature, grade, stability control, and longitudinal and lateral acceleration. The TorqueFlite is capable of handling a variety of duties. As evidenced by the wide range of vehicles Chrysler Group has seen fit to equip with the eight-speed transmission, the TorqueFlite is capable of handling a variety of duties. Since its 2012 introduction, the TorqueFlite has gone from performing cog-swapping duties in Dodge Charger and Chrysler 300 models equipped with the 3.6-liter Pentastar V6 to changing gears in vehicles such as the Pentastar- and Hemi-powered Dodge Durango, Jeep Grand Cherokee and even the Ram 1500 EcoDiesel. For the 2015 model year, the eight-speed is finding its way into even more vehicles with the addition of a third version. In addition to the American-made TorqueFlite 845RE and 8HP70, the new 8HP90 will be manufactured in Saarbrucken, Germany. The 8HP90 is designed for higher torque loads, making it ideal for high-performance vehicles like the 2015 Dodge Challenger SRT Hellcat. The already-in-use 8HP70 will expand its duties to be used in 2015 Hemi models such as the Dodge Charger, Challenger, and Challenger SRT8. You can see the list of those benchmarks in Chrysler's press release below.