Supercharged Grand SRT8 And Twin-Turbocharged Cayenne Go Head-To-Head
Porsche's Cayenne Turbo is widely accepted as being the best example of a sports sedan in SUV form. It almost goes without saying then that such a platform, when modified by TechArt-one of the best known and most respected Porsche tuners in the world-should pack a punch so powerful no other truck would dare get in the ring with it.
After considerable searching, we found a contender brave enough to go blow for blow with all 600 turbocharged TechArt horses: a Jeep SRT8 belonging to professional race driver/mortgage banker, Cort Wagner. This is no regular SRT8, as is obvious by the sizable Paxton supercharger bolted to the 6.1-liter V-8. While we wouldn't normally put a Porsche in Jp magazine, this showdown was just too tempting to ignore.
After just a few rounds, however, it was obvious that this heavyweight match was a non-contest. The victor, however, may surprise you.
Strength In Numbers
It's amazing how performance statistics like horsepower and torque don't tell the whole story. With 600 hp and 627 lb-ft of torque, the turbocharged TechArt Magnum Porsche was slow off the line but really picked up once the boost kicked in. We clocked the Magnum at 5.4 seconds to 60 mph, slower than Porsche claims for the stock SUV. This was disappointing but not all that surprising, as tuning a twin turbocharged engine for larger numbers up top usually means you will lose a little down low.
The SRT8 Grand Cherokee is fitted with a Paxton supercharger installed by GS Motorsports. It takes more than just a bolt-on blower to make power, though, and so the folks at GS went about optimizing the engine in every way they could with higher-flow injectors, a new valvetrain, ported-and-polished heads, a ported intake manifold, a Mopar/Corsa exhaust system, an intercooler, and a GSM 3000 stall converter that lets the truck rev up into the more powerful rpm range before you launch.
On an AWD dyno, the truck laid down 502 hp and 498 lb-ft of torque. Those numbers don't sound all that amazing, but when you consider that the drivetrain loss on an AWD dyno is up to 25-percent compared with the usual 15-percent for a front-drive or rear-drive car, we are actually looking at crank numbers north of 612 hp and 607 ft-lbs, respectively.
More shocking than those numbers is the 3.5-second 0-60 mph blast, which sounds like it belongs to a Nissan GT-R and not a Jeep.
After repeating and re-repeating the 60-mph run in sheer disbelief (and continuously coming up with the same numbers every time), we decided to move on to the more realistic 100-mph sprint test. Let's face it, a rip to 60 mph is over too fast, and if you're really going to open it up, the 100-mph mark is a nice one to hit.
The numbers, we surmised, should definitely be closer in this test because the SRT8, with its high-torque-at-low-rpm supercharger, would pull less impressively at highway speeds, whereas the Magnum's turbochargers, once in boost, would pull more impressively. We were wrong.
That's not to say the Porsche didn't impress, as we clocked an admirable 12.2-second run to 100 mph. The truck's lack of low-end pull continued to frustrate us, however, and if drag racing teaches anything, it's that a fraction of a second down low can mean a whole second up top.
As for the Jeep, it continued its dominance with a blistering 9.5-second blast to 100 mph-not far from what a $200,000 Ferrari F430 can do.
Even Wagner, who drives this truck every day, was shocked by the numbers. "I knew it was quick, as it is a big cube motor and they run pretty good stock, but it really surprised me how well it came out of the hole," he says. "I mean, it barely spun the wheels, and bang-it was gone."
That bang has a lot to do with the high-stall converter, which helps the car launch as if by a steam catapult shooting it off an aircraft carrier-it is definitely the best $800 any SRT8 owner can spend on the truck.