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“We are still dealing with physics here. I just want you to remember that.” So says Erich Heuschele, manager of SRT vehicle dynamics to the 20 or so writers he’s about to turn loose on a racetrack in the Jeep Grand Cherokee Trackhawk. We’re dealing with physics, sure, but also an earnest effort to defy them with equal parts horsepower and lunacy. Say, “707-horsepower Jeep” to anyone who hasn’t been paying attention and they just wiggle a finger into an ear and squint at you. “Huh?”
We did drive the maximum Jeep on public roads, but this Grand Cherokee has “track” right there in its name, so we also hit Club Motorsports, a New Hampshire club circuit so new that crews were still installing Armco the week before we showed up. It’s a 2.5-mile StairMaster that works its way up and down 250 feet of elevation change at a maximum 14 percent grade. Keeping his new Trackhawks from bending that fresh Armco is something Heuschele cares deeply about.
The topography, on the other hand . . . nobody’s too worried about that. Few things flatten hills quite like 707 horsepower. Insane as it may be, the Hellcat engine at least should be familiar by now. Down 251 cubic centimeters compared with Mopar’s naturally aspirated SRT engine, it’s a 6.2-liter V-8 capped with a 2.4-liter IHI supercharger that stuffs the Hellcat’s eight cylinders with 11.6 psi of boost to generate such jaw-dropping output. In the Trackhawk, it makes its full complement of horsepower but loses 5 lb-ft of torque compared with the car applications—to 645—due to a more restrictive exhaust system.
Caught up in a sledgehammer fight against the supercharged V-8, engineers applied the same blunt-force mentality to the rest of the powertrain: There’s a beefier transmission and a stouter transfer case, and the rear driveshaft, half-shafts, CV joints, and differential are reinforced. The front axle is unchanged from the regular SRT Jeep. That transmission is still a ZF-supplied eight-speed automatic, now christened 8HP95 and officially rated to handle up to 811 lb-ft. The transfer case routes torque forward with a wider chain than in the naturally aspirated SRT, with forged-steel sprockets instead of powdered-metal ones. Tube-wall thickness is up on the rear driveshaft, while the differential housing gains a mount, going from three to four. Inside, the diff itself goes from two spider gears to four, with modified tooth geometry for greater strength. The Hellcat engine alone outweighs its naturally aspirated brother by 108 pounds, and the bigger-hammer specification raises the Trackhawk an additional 105 pounds overall above the Grand Cherokee SRT, according to Jeep.
Like the Challenger SRT Demon, the Trackhawk gets a Torque Reserve function to aid launching. With launch control activated, this system cuts fuel to individual cylinders while the Jeep is brake-torqued, allowing the engine to rev higher and the supercharger to build more boost. With the function engaged, the blower generates 6.4 psi while sitting at the line. What the Trackhawk doesn’t get is any more tire than the Grand Cherokee SRT. Lift your foot off the brake and the Trackhawk will squawk all four 295/45ZR-20 Pirellis (either all-season Scorpion Verdes or more aggressive P Zeros) on its way to what Jeep claims is a 3.5-second zero-to-60-mph time. The company says the Trackhawk will burn through the quarter-mile in 11.6 seconds, but given our recent inability to match SRT’s performance claims, we suspect that figure might also be just out of reach. Give or take a few tenths, though, Club Motorsports’ 14 percent grade felt as flat as Google Maps’ 2D view (in which, incidentally, the track still shows up as dirt as of this writing—we told you it was new). Our one complaint about the engine is that we want more blower whine when the accelerator is matted. There’s a good bit under lighter loads, but at full throttle, it fades behind a raging gargle blaster of an exhaust roar so fierce it sounds like the tailpipes are emptying into the cabin. (“The call is coming from inside the house!”)
Barreling down Club Motorsports’ hills emphasizes the rest of the Trackhawk’s skill set. It retains the SRT’s control-arm front and multilink rear suspension layout, but the springs are 9 percent stiffer up front and 15 percent stiffer out back. Not surprisingly for something so heavy and with so much rubber at each corner, it’s quite stable—a desirable trait on a course with lots of camber variances. But toe into the brake and it’ll rotate—or lay into the brake and it’ll dance disconcertingly, even in a straight line. The steering is a touch slow but heavy enough for perceptible weight to bleed off as the nose starts to wash out. Although the brakes always felt strong, pedal travel increased to an alarming degree over the course of our lapping session.
At 15.7 inches in diameter, the Trackhawk’s two-piece (aluminum hat and iron friction surface) front rotors are 0.8 inch larger than those on the naturally aspirated SRT Jeep. The 13.8-inch rears are the same, as are the six-piston front and four-piston rear calipers, but the Trackhawk’s pinchers get a coat of yellow paint. Jeep hopes you like it, because it’s what you get regardless of exterior color or whether you opt for the standard aluminum-finish or optional satin-black wheels. The latter are three pounds lighter per corner.
Those yellow calipers are one of the Trackhawk’s few exterior tells. Others include the deleted fog lights, their nests hollowed out for an oil cooler on the passenger’s side and a cold-air intake on the driver’s side. A new rear fascia accommodates the quad exhaust outlets. There’s a subtle “Trackhawk” badge on the lower right corner of the liftgate and “supercharged” script below the usual Grand Cherokee lettering on the front doors.
Inside, there are Trackhawk logos on the seats, a Trackhawk-exclusive red-and-black two-tone interior option, and a 200-mph speedometer. That’s optimistic by only 20 ticks, according to Jeep, but by its orientation the speedo always downplays your speed: 0 is straight down, 200 is straight up, and at 100 mph, the needle points horizontal. To most of us, a declined pointer is asking for more mph, but this one only starts to close on flat at extralegal speeds.
The rest of the interior is standard Grand Cherokee SRT fare: spacious, with comfortable seating front and rear and a sizable cargo hold. There’s a reason the Grand Cherokee is one of the best-selling SUVs in the country, and those 200,000 or so annual buyers aren’t making a bad decision. While the Trackhawk’s stiffer ride is noticeable on New England’s bumpy country two-lanes, it’s not so harsh as to be a turnoff. Better not try to turn off those roads, though, because while the Trackhawk is a Jeep, its approach and departure angles are more like those of a Toyota Camry.