Specialty File
Just as the Dodge Viper brand is about to be quietly euthanized or sold to a den of Cub Scouts, along comes the far less expensive but equally tweakable Challenger—a tuner’s dream come true. Not surprisingly, major Mopar power hogs are now making pilgrimages to John Hennessey’s Texas shop. As this was written, 15 Challengers had filled 20 of Hennessey’s service bays, and the man had prepared a menu of seven different engine upgrades for the stock 425-horse SRT8.
For our test, we chose the third-strongest recipe, the HPE600 Turbo, which retains the Hemi’s stock displacement but benefits from 6 psi of boost, courtesy of a single Precision 67HPSH turbo with a 44-millimeter waste gate. The cylinder heads were aggressively ported and polished until enough metal was removed to lower compression to 9.6:1. Hennessey then installed an air-to-air intercooler, cold-air induction, a turbo oil-pump scavenge system, stainless headers, and a Corsa exhaust.
The result: 620 horsepower at 5500 rpm and 650 pound-feet of torque at 4200 rpm. The engine package alone costs $29,500 installed, although that works out to only $151 per bonus horsey.
Our car was further modified with a KW coil-over suspension, anti-roll bars, StopTech brakes, a one-inch ride-height reduction, and 20-inch alloy wheels. Those bonus underpinnings, and some other modifications, pushed the cost to $55,455—a lot to tack onto the SRT8’s original 42-grand sticker.
What you notice first about the HPE600 is a panoply of peculiar but strangely intoxicating noises. First, the turbo’s oil-scavenge pump sometimes sounds like one of the front tires gently rubbing a fender liner. Second, the Corsa exhaust emits what must surely be the deepest elephant yowl this side of Kenya. Third, when you lift at wide-open throttle, the blow-off valve lets fly with a sigh that resembles the whoosh of doors closing on the starship Enterprise.
Step-off is a little unpredictable—the idle on our tester was surging from 900 to 1200 rpm. But in town, at part throttle, the HPE600 proved satisfactorily smooth and docile. However, should you allow engine revs to surpass 3100 or so, all bets are off. It’s as if God reaches down and touches His BiC lighter to the infinite universe’s shortest fuse. You can spin the Michelin PS2s all the way to the limiter in first gear, and they’ll keep spinning halfway through second, at which point you’ll lift for fear of setting something alight—the road, perhaps.
At the track, the HPE600 hit 60 mph in 3.9 seconds and 100 mph in 8.4 seconds. That’s 0.9 second and 3.0 seconds quicker than the stock SRT8. It cleared the quarter-mile in 12.2 seconds at 120 mph, 1.1 seconds and 12 mph in front of an SRT8. To 150 mph, in fact, the HPE600 will be leading the stock Dodge by an amazing 11.8 seconds and would lag behind, say, a Porsche 911 GT2 by only one second.
We’d have preferred a more linear, even-handed power band—the explosion at 3100 rpm can catch you off guard, especially in the midst of tight turns. And the suspension and tire upgrades, which did indeed raise skidpad grip from the stock 0.86 to a neck-bending 0.95, cost a lot and did minor damage to ride quality. We’d stick with the engine package alone.
In the movie Dr. Strangelove, Slim Pickens waves his cowboy hat as he rides a nuclear weapon dropped from a bomber. Now we know how he felt.
Hennessey Performance Engineering, 9281 SW Interstate-10 Frontage Road, Sealy, Texas 77474; 979-885-1300; www.HennesseyPerformance.com.
