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Jeep SRT8 vs Porsche Cayenne

Posted in Project Vehicles on January 1, 2010 Comment (0)
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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.

100-Mph Stretch
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.

Less-Weight Heavyweight
After our two straight-line performance tests, it was beginning to look like a whole host of factors were favoring the Jeep. For starters, it had a better torque curve-and that high-stall converter ace up its sleeve. Torque may be important on a sports car, but it is vital to these SUVs with all-wheel drive and thousands more pounds to pull.

Which brings to light the second factor: weight. At 5,191 lbs, the Cayenne is almost 400 pounds heavier than the SRT8. All that dead weight is yet another contributing factor to the Cayenne's weak launch. Needless to say, it certainly didn't help when it came to the braking test.

Hit The Brakes
Both these trucks are set up with similar braking systems-up front, in particular, where they both have eight-piston calipers. In our 60-0 braking test, the Jeep was once again the victor with a total distance of 118-feet, versus 140-feet for the Porsche Magnum. It appears as though that extra 400 pounds makes a substantial difference.

Bang For The Buck
When it comes to the old bang-for-the-buck factor, the American SUV is the favorite-no surprise there. What is surprising is by how much. Wagner's supercharged SRT8 cost him, all in, just under $60,000-less than half the price of a fully tuned Porsche TechArt Magnum. In fact, the supercharger alone only costs $7,200.

With a stable of cars that includes, among others, a Carrera GT and a CLK63 AMG Black Series, it's apparent that Wagner didn't build this truck on the cheap because he had to. So why then?

"I really like building and engineering cars," he says. "It's been a passion of mine since I was 15. I got really sick of all these $100,000 to $150,000 trucks that, relatively speaking, don't go quickly at all and cost an arm and a leg.

"I need a car in the fleet that I don't really worry about valeting or hauling stuff in," he says of the truck's utility. As for the performance, Wagner is a race car driver, after all. "I also need a truck that I won't get beat in, as losing any race is not an option for me."

But What About Class?
What the SRT8 lacks is ride quality and refinement-not to mention style. The Jeep rides like, well . . . a Jeep with a slightly stiffer suspension, thanks to the Eibach springs. The Porsche, on the other hand, provides a comfortable driving experience that has negligible body roll. In fact, you can go around corners in the Magnum at speeds you wouldn't even think of in any other SUV.

As for the interior, Wagner has no qualms about admitting defeat in that category. "Yes, it would be great if it were a bit nicer," he says, adding that a leather dash and door panels would be nice. "But honestly, the minute you start going in that direction, you might as well buy a Range Rover." Besides, he retorts, the truck does come with Bluetooth, a six-CD changer, satellite radio, heated seats, navigation, voice command, and a backup camera.

When it comes to style, the Magnum's flared fenders and unique Porsche design give it a show-factor comparable to the SRT8's go-factor. Still, there is something alluring about the hard edges of the Jeep Wagner refers to as his Quick Pig.

Cruising down the freeway, the SRT8 doesn't draw many stares, while the Magnum has necks snapping wherever it goes. Even Wagner will admit that his Jeep doesn't have the pizzazz of the TechArt Porsche. "We all want to look like rappers here in L.A.," he says, and that's exactly what people might think you are in a white, widebody Cayenne.

Sound Off
The Porsche Magnum also wins in our subjective exhaust sound test. You can hear the whoosh building as the turbos spool, and the V-8 has a great grunting roar when you really get into the power. The SRT8, on the other hand, is deafening. With the two trucks side by side, you can only hear the blower on the Jeep-even if you're in the Porsche. The supercharger doesn't whine, so much as it screams bloody murder.

In fact, Wagner's Jeep never stops being obnoxiously loud. Around town, the Porsche can be completely civilized if you want it to be, whereas the Jeep constantly makes the sort of racket that might only be considered acceptable for a sprint racer.

Heavyweight Champ
We can't help but go with the SRT8 as the winner of this championship bout. Sure, the Porsche is more civilized, looks better, rides better, and has a vastly more luxurious interior, but you just can't argue with the Jeep's performance. Some vehicles push you back in your seat, but the way the torque gets delivered in this supercharged SRT8, you'll be lucky if it doesn't throw you right out the back.

AT A GLANCE Supercharged Jeep SRT8 Porsche TechArt Magnum
Engine 6.1-liter V-8 Twin-turbo, 4.5-liter V-8
Engine Mods Paxton Novi 1500 supercharger, intercooler, ported- and-polished heads, new valvetrain, ported intake manifold, oil cooler, 45-lb fuel injectors, Mopar/Corsa exhaust system TechArt T3 power upgrade including two turbochargers, two intercoolers, oil cooling lines, intercooler pipes, intake pipe, air filters, headers, cats, midpipe, muffler and control arm bushings
Horsepower 612 @ 5500 rpm 600 @ 6125 rpm
Torque (ft-lbs) 607 @ 5250 rpm 627 @ 3300 rpm
Transmission Mods GS Motorsports 3000 rpm stall converter N/A
ECU Mods DiabloSport handheld ECU tuner TechArt ECU
Body & Chassis Mods Silver-painted chrome trim, satin black-painted window trim, factory rear spoiler, bi-xenon headlights, HID foglights Magnum widebody conversion and aero hood
Wheel, Tire, & Brake Mods Forgiato 22x10 Vizzo wheels and 295/30/22 Michelin Diamaris tires, Brembo eight-piston calipers w/ 16-inch rotors (front); Forgiato 22x10 Vizzo wheels and 295/30/22 Michelin Diamaris tires (rear) 22x10 TechArt Formula GTS wheels w/ 295/30/22 Michelin Diamaris tires, eight-piston calipers with 15-inch rotors (front); 22x10 TechArt Formula GTS wheels w/ 295/30/22 Michelin Diamaris tires, four-piston calipers with 14-inch rotors (rear)
Suspension Mods Eibach springs TechArt air suspension unit
Interior Mods Alcantara steering wheel TechArt steering wheel and pedals
Weight (lbs) 4,819 5,191
0-60 MPH (sec) 3.5 5.4
0-100 MPH (sec) 9.5 12.2
60-0 Stop (ft) 118 140
Costs
Initial Vehicle Cost (used '07) $36,000 $70,000
Engine $11,000 $39,900
Exterior $2,500 $29,800
Wheels & Tires $5,000 $7,388
Suspension $800 $2,900
Brakes $3,500 $14,000
Total $58,800 $163,988

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