For all the non-believers, we've posted dyno charts supplied by Hennessey showing the actual figures his company got. The first chart shows their stock '08 Viper, the next shows the Venom 650R running catalytic converters, while the final chart shows the Venom 650R without catalytic converters. Figure in Hennessey' estimated 12 percent drivetrain loss and you'll get his 678 horsepower.
In a recent email, John Hennessey had this to say: "Based on these facts and given the fact that our test mule's engine is not fully broken in yet, I believe that our power claims are true and accurate. I would estimate that once the motor has 3000 miles on it that the dyno numbers could increase by another 8 rear wheel hp. Further supporting our power ratings and more importantly, our track data shows improvements in 1/4 mile trap speeds of 5 to 7 mph."
It's well-known that the 2008 Dodge Viper SRT-10 is no weakling. Producing 600 horsepower from its mammoth 8.4-liter V10 engine, Dodge claims the 0 to 60 mph sprint is said and done in under four seconds, with 0 to 100 mph runs being dispatched in the low 12s. Heady stuff. But if you want even more power, you'll have to take a trip down aftermarket lane.
One of the suppliers to power-hungry Viper owners is Hennessey Performance Engineering. Known for its twin-turbo-equipped Vipers and claims of massive performance, Hennessey is well known to the tuner community and has just announced a new performance kit for the 2008 Viper. The numbers look appealing: 678 horsepower - a whopping 78 more ponies than stock - and 645 lb-ft of torque, as opposed to the stock Viper's 560 lb-ft. Yet, a quick look at what Hennessey's Venom 650 kit includes could easily leave one a little skeptical.
For your $8,950 (or $11,500 installed) you get a plethora of special badges, two-piece cross-drilled brake rotors front and rear, a K&N airfilter, high-flow catalytic converters, and a stainless steel performance exhaust system including headers. That's 78 horses from an intake and exhaust, according to Hennessey. A brief phone conversation had John Hennessey himself claiming he's got the dyno charts to back those figures up.
Hennessey also said that he believes Chysler's horsepower rating to for the 2008 Viper to be on the conservative side. He claims the rear-wheel horsepower figure for his stock Viper to be 546, while 595 rwhp was seen from the Venom 650 kit. Assume a 12 percent or so drivetrain loss factored in to those figures, and we're getting closer to Hennessey's figures. We'll update this post later, provided we can get the charts posted to silence what may be a good deal of naysayers.