Je vous apporte un petit article déniché dans le magasine Road&Track sur la Venom GT.
L'article est malheureusement en anglais, si quelqu'un à envie de traduire... (J'ai les word et excel pour ceux qui voudrait traduire)
The proverbial engine with a car built around it, the Hennessey Venom GT combines
the best attributes of Chevy's pushrod small-block V-8 with the aluminum mono-coque
and passenger cell of the Lotus Exige.
Note the beautiful symmetry of the sizable Garrett turbos, “cherry bomb" polished
charge coolers and twin pop-off valves near the rear window before the tract does a
180 to feed the intake manifold. This particular 6.2-liter powerplant has the
internal fortitude to make as such as 1400 bhp (!) by tweaking the adjustable
wastegates (driver’s side pictured below).
Another view of what biologists would term bilateral symmetry. The Exige ends aft
of the seats, where Hennessey's robustly triangulated subframe, scratch-built
double A-arm rear suspension and monster powerplant begin. Stealthy 20-in. alloys
encircle Brembo carbon-ceramic rotors and 6-piston calipers. The tight track
revealed significant low-speed push, but believe me, rear traction is your sole
focus when squeezing that skinny right pedal.
Pahrump, Nevada- It’s all a bit surreal, like I’ve stumbled into the first minutes
of a Bond movie. With my right foot queuing up 12.5psi from a pair of massive
Garrett GT35R turbos, I’m shot from a cannon down the front straight… into the
rotor blast of a helicopter hovering a mere 20 feet above the track surface. Pilot
John Morris (also the track owner) grins through the canopy like a Cheshire Cat;
videographer Jay McNally leans out the flitting chopper like a sidecar monkey,
contorting for the best shot.
And if those ominous rotors set on Journalist Frappé didn’t put me into sensory
overload, the Venom GT’s raw acceleration does - a savage burst of cheek-smooshing,
gut-compressing, momentarily brain-addling force, the strongest I’ve ever
experienced in a road-going Car. The twin pop-off valves screech like an 18-
wheeler’s air brakes as I lift, then the Venom GT through one of the tight right-
handers and - with the caution of a bomb squad’s eldest member - get back on the
throttle. Historically, the explosive onset of power and high-cornering loads have
been shown not to mix, and there’s a heart-stopping yaw moment… followed,
surprisingly, by a booked-up Michelins and that addictive rush of acceleration.
Must... show… restraint. This car already been sold, and that check won’t clear if
I was it into an $895,000 ball of vacuum-bagged carbon fiber and extruded aluminum.
Back in the pits now, and John Hennessey seems pleased at my greenish complexion
and foal-like unsteadiness as I extract myself from the Venom GT’s cockpit. The
lapping session here at Spring Mountain Motorsports Ranch has been as brief as it’s
been exhilarating, but if seat-of-the-pants validation counts for anything, it’s
clear he’s built the most formidable supercar in America, and possibly the world.
No stranger to building road cars with quadruple-digit horsepower numbers, John
Hennessey took top honors back in our “Speed Kings” shootout (September 2007),
where his 1100-bhp twin-turbo Viper bested even the almighty Bugatti Veyron from a
standing start to 200mph. Said Steve Millen, our driver that day: “Holy Hell! This
is a wild ride. It just wants to go sideways in every gear. Thankfully, the
talented Kiwi kept it just straight enough to hit 200 in 20.3 seconds, a staggering
3.9 sec. quicker than the monster from Molsheim. This, note, was done with a
pounds-per-horsepower number of 3.1, far more acceleration-conducive than the
Bugatti’s 4.5, even if the Bug does get out of the hole a lot more efficiently with
its all-wheel drive. What, thought John shortly after hoisting the trophy aloft,
might a car with a 2.6(!) ratio be capable of?
“I started wondering, okay, what’s next?" says Hennessey, who mulled over slightly
lighter, even more powerful versions of both the Viper and Ford GT, but rejected
them on grounds of being too race-car minimalist. “I was joking one day about
taking a Lotus Exige and putting our Venom 1000 engine in the back of the car. And
we all laughed about it; laughed about it for a couple of weeks.” But a preliminary
sketch was followed up by a full set of renderings. “When they came in, I looked at
the car, and by that point I’d stopped laughing. I thought, we could build this
car.”
And here it is, rich silver paint glowing in the stark Nevada sunlight. At 2635 lb
with all fluids including 18.5 gal. of 93 octane, it’s about the weight of a Honda
Civic, but with 8.6 times the power. Fire it up and it’s clear the guttural
burble/pop at idle can only come from a V-8’s firing order. The Viper V-10’s
weight, bulk and questionable future availability were all negatives, and Hennessey
had become quite fond of Chevy’s 6.2-liter aluminum small block through prior
Corvette ZR1 projects.
“Loved the power, loved the sound…"
Of course, this is no ordinary Chevy small-block; it has to live to 7200 rpm, make
a staggering 1200 bhp and cope with off-the-charts cylinder pressures from the
ceramic-bearing turbos. To this end, the LS2 block is fitted with Darton sleeves,
Cometic head gaskets and CNC-ported cylinder heads, cinched together with the
finest ARP fasteners. Seemingly every rotating and reciprocating bit is forged,
including dished aluminum pistons, H-beam steel rods and a steel crank, the last
held by billet main bearing caps. Oiling is via a dry-sump system and fueling is
handled by twin Bosch in-tank pumps that feed 96 lb./hr injectors. The engine bolts
up to a Ricardo 6-speed manual transaxle that’s identical to a Ford GT’s, ratios
and all, that puts power to the massive 335-section Michelins through a Quaife
limited-slip diff.
Raise the Venom GT’s rear-hinged engine cover (lined with gold foil, incidentally)
and it`s clear that Hennessey sweats not only the power but the appearance. Aft of
the seats, the Exige’s aluminum monocoque architecture ceases and Venom GT begins
with a stout chrome-moly steel subframe, triangulated by two beautifully gusseted
V-shape braces that bolt up to the rear hoop of the considerable rollcage
structure. There’s tidy symmetry in the twin water-to-air charge coolers, the
blow-off valves, the wastegates, turbos and conical air filters. And the muscle-
bound central exhaust, with 3.5-in. dual tips poking through the bodywork’s mesh,
has a beautiful golden cast… it’s sandblasted stainless steel that takes on its
distinctive hue when heat is applied.
Inside, the Exige’s basic interior intact, but embellished for slightly greater
comfort and style. There’s lots of black diamond-stitched Alcantara, smooth leather
and a carbon-fiber sheath over the 2-dial instrument cluster. Bits of exposed
aluminum remain, completely fitting here.
And the stout rollcage is evident, though its tubes are wrapped in the same
diamond-tuft microfiber that lines the seats, door panels and dash top. My helmeted
head fits neatly in a triangular recess of the X-brace connecting the front and
rear hoops… tight, but just enough room. The view straight back? Shiny blow-off
valves, black mesh and ducting, but at least the outside mirrors are large and
well-placed.
Outside? It’s an Exige with a Gold’s Gym membership, ripped muscle with that
Porsche 917 long-tail look from its stretched wheelbase (at 110.2 in., it’s a
substantial 19.7 in. longer than that of its donor chassis) and massive rear
fenders that swell around the rear Michelins. The Exige’s visage is maintained with
Lotus headlights and sharply peaked fenders, but broadened and underscored
(literally) with a thick splitter that incorporates twin underbody venturis farther
back.
At the rear, the taillights seem to float in the mesh grille, and a generously
straked underbody diffuser extends well beneath the engine. Combined with the rear
wing (hydraulically adjustable for height and angle of attack, yet fixed at this
stage of development), Hennessey estimates there measures will generate downforce
somewhere in the vicinity of 1200 lb. at 150 mph, according to CFD simulation.
Hennessey will be the first to admit that there’s much more development to be done.
Although he and chassis guru John Heinricy (yes, that Heinricy. the 39-year GM
performance veteran with five national SCCA T1 championships, assistant chief for
the C4 & C5 Corvettes, etc.) have created a monster in the best sense, another year
of optimizing the Venom GT awaits before production hits full stride. For instance,
the active KW suspension (an electrohydraulic system can raise the car by 2.4 in.)
and the rear wing will be programmed to work together to achieve downforce, reduce
drag or produce a happy medium, depending on the situation. Motec engine management
will replace the current reflashed GM ECU and HKS boost controller, and a
traction-control system that adjusts throttle position and boost level ought to
tame the Jekyll/Hyde power hit. Plans include test sessions at the Nurburgring in
the summer of 2011, with Hennessey hoping to ultimately break the 7-minute barrier.
I‘m reunited with the Venom one last time at our usual El Toro lest venue, where I
can flog it around for additional impressions. The lightness of the steering,
clutch and the delicacy of the shift action seem incongruous with the massive
power, and even with roughly 60 percent of the weight over the rear axle, the 235mm
front Michelins -dwarfed by the rear tires- feel overtaxed in hard cornering. A fix
is in the works, as 255s on 1-in.-wider wheels will be fitted on future builds.
But let’s celebrate what this car does best, with a mile of runway before me.
Again, hard through the gears, turbos at full whistle, the Venom inhaling the
horizon in one last tunnel-vision orgy of speed. The pavement seams are no longer
felt separately, now a continuous drum roll of vibration and intensity. The tach
reads 6100 in 4th, or about 165 mph, before exhausting available runway and nerve.
Just getting started…a shame.
It’s then hard on the carbon-ceramic 6-piston Brembos, then a cool-down crawl to
the trailer. After this thrill ride, a theoretical top speed of 272 mph seems
entirely possible. And Hennessey has a history of delivering on crazy promises.
Twelve hundred horsepower. Less than 2700 pounds. “Do the math," says Hennessey,
“and the outcome is basically a car that’s thrilling and borderline scary to drive
sometimes.” Here’s to being a little scared.
