Power Comparison

Bring together six cars with an average of 500 horsepower apiece, each massaged by one of the country's top tuning houses, out to Firebird Raceway in Phoenix, Arizona, and the sounds, chords, and harmonies of horsepower come into vivid, stereophonic relief. We brought the cars there not to anoint one emperor of speed, but to appreciate each on its own merits, seeking symphonic convergence.

Sound is an overwhelming force with Hennessey Motorsports' Dodge Viper Venom 600. Larger cylinder bores and longer-throw crank strokes the mammoth V-10's displacement up from a merely gargantuan 488 cubic inches to a stupefying 520. Every odd exhaust pulse pounds from the side pipes like a cannon shot and reverberates for a moment before being overridden by the torrent of pulses right behind it. It's raw, almost unnerving, and completely glorious.

John Lingenfelter's 383-cubic-inch LT1 Corvette and Kenne-Bell's supercharged 4.6-liter DOHC 32-valve Mustang Cobra both strike familiar chords. In contrast to the Viper, it's almost soothing to hear the Vette's raspy V-8 note, or the slight whine of the Kenne-Bell Whipplecharger supercharger. For Americans, nothing bespeaks high performance like a V-8, and the comfort of that tradition is nearly as compelling as the performance promise of both these muscular engines.

Mechanical harmony is a German tradition, and neither TechArt's supercharged Porsche 911 Carrera nor RennTech's 7.0-liter version of the 12-cylinder Mercedes S600 Coupe disappointed. The low wail of the Porsche's 3.6-liter air-cooled flat-six is quite familiar after nearly 33 years of production, but it takes on a whole new dimension when equipped with a ZF centrifugal blower. Turbochargers muffle the Porsche's exhaust, but TechArt's supercharger adds an elemental noise to an already exhilarating engine. Meanwhile, the supreme balance of the big Merc's motor is wholly undisturbed by RennTech's inflation of its displacement and radical increase in output. The RennTech engine has perfect pitch and the sort of power one expects of a turbine helicopter.

Finally, there's the DC Sports Acura NSX. This young company's simple, subtle tweaks to the 3.0-liter DOHC V-6 wondermotor takes it from flat-out marvelous to complete virtuosity. With careful tuning of the VTEC systems, past 6000 rpm it's as if someone had lit the afterburner on a Stradivarius.

Once our performance testing and hot laps of Firebird's road course had been completed, the six supertuned cars headed over to Pro Dyno in Tempe to spin the rollers of its DynoJet chassis dynamometer. At the rear wheels, the cars averaged an ungodly 387 peak horsepower and 371 pound-feet of torque. And not a single vehicle proved temperamental during testing or experienced any mechanical malfunction.

Hennessey Viper Venom 600 - 635HPThe Scariest Street Car We've Ever TestedNuh-uh...no way: This car isn't for novices. Or for rational humans of any race, creed, or political persuasion, for that matter. Hennessey's Viper Venom 600 has gone so far past the line of sanity, it's become wholly and unequivocally demented. With a dyno-certified 528 rear-wheel horsepower (that's about 635 at the crankshaft), this bulging-fendered 8.5-liter go-kart from hell is scarier to experience than a carjacking. And that's at idle. Crack open the throttle and it becomes a Texas chainsaw massacre on wheels.

Comparatively speaking, a stock Viper with its merely monstrous 8.0-liter/415-horse V-10 is a tabby cat full of Darvon. Never mind the fact that this tabby cooks 0-60 mph in five seconds flat and rampages the quarter mile in 13.2 seconds at 113.4 mph. However, next to the Hennessey Venom's 0-60 rush of 3.8 seconds and quarter-mile brain drain of 11.8 seconds at 124.0 mph, the stock Viper looks more like it belongs in a kiddie carnival.