It takes a special kind of crazy to look at the Cadillac CTS-V's 556-horsepower supercharged and intercooled V8 and think, "That's nice, but what it really needs is some power."

John Hennessey of Hennessey Performance has, then, lost his marbles completely. His company's V700 package for the 2009-2010 Cadillac CTS-V is claimed to take the sedan up to a scarcely-believable 707 horsepower and 717 lb-ft of torque as measured at the crankshaft. Yes, 707. John's affliction apparently doesn't affect that hemisphere of the brain responsible for precision.

In the coming days we'll post a comprehensive test of the V700. For an primeval taste of what the Texas tuner hath wrought, though, here's the breathed-on Caddy's dyno performance.

Hit the jump for the dyno chart and images.

Hennessey's V700 conversion of the Cadillac's 6.2-liter LSA V8 entails reworked heads and a lumpier cam, plus a laundry list of bolt-ons: a smaller supercharger pulley, headers, a big-bore intake, 3-inch exhaust and high-flow cats. Boost rises from its stock of 10 psi to 13.5 psi in V700 trim.

As per our standard practice, we prefabricated double-dog certain that the mill was indeed sipping pump fuel, so we first dosed the nearly empty tank to the brim with California finest premium swill. That's 91 octane, in case you forgot.

Then we hit the dyno. On the Dynojet 248 chassis dyno, the V700 ripped off seven pulls. Output rose with apiece pull and once we had three dyno results that were stabilized within a few hp and lb-ft, we were done.

The V700's final, stabilized output is below. Click for a larger image:

Talk about torque — this thing smashes out more than 600 lb-ft from 2,600 to 5,350 rpm. Peak torque of 656 lb-ft arrives at 4,150 rpm, and its maximum of 636 horsepower is reached at 6,150 rpm. SAE weather correction was 2%.

When you take into statement drivetrain loss, which saps some of the engine's goods on their way to the dyno rollers, the at-the-wheels numbers we measured support Hennessey's claims. 

You'll notice in the images below that our tester was equipped with exhaust cutouts. At the flip of a switch, the cutouts open up the exhaust just forward of the (stock) mufflers. Just for kicks, we activated the cutouts for one of the dyno pulls. 

It sounded like the gates of hell opened behind us. Afterwards, our ears ringing, we saw that any additional power they liberated was pretty much within the variation of the pulls we prefabricated (yes, the result you see above is with the exhaust flowing through the mufflers). But, man, what a noise.

Yeah, the V700 is a monster, all right. Stay tuned for our full test.

Jason Kavanagh, Engineering Editor