Hennessey Prowler GTX
One Very "Happy"
From the April, 2000 issue of Motor
/ Photography by Wesley
By the third run down the test track, I was getting a little too giggly.
Perhaps it was from the Viper RT/10-like acceleration of the nitrous
oxide-boosted Hennessey Prowler GTX. Or maybe it was the whiff of the
laughing gas I got when the system was purged prior to testing. Either
way, I was having loads of
which is the sole reason for owning John Hennessey's latest creation.
"The whole essence of a hot rod is to go fast and
says Hennessey. With the GTX, Hennessey improved the Plymouth Prowler's
already audacious appearance a little bit and made it a whole bunch
From its introduction, the Prowler's emphasis was on "show," with "go"
an afterthought. Even after a '98 upgrade to a 3.5-liter/253-horsepower
SOHC V-6, the stock Prowler looked a lot faster than it went.
Hennessey's challenge was to make the Prowler significantly faster for a
reasonable price. Rather than supercharging the existing engine or
transplanting in a
Hennessey chose to add a nitrous oxide injection system. Other engine
work was limited to light head porting, a freer flowing exhaust system,
and a low-restriction K&N air filter. These last modifications up the
GTX's horsepower to 290. But flip the nitrous switch (located in the
console between the seats), go to wide-open throttle, and the GTX can
reach a peak of 365 horses and a whopping 450 pound-feet of torque. The
result is 0-60 mph in blazing 4.5 seconds with a rapid
13.1-second/105.3-mph quarter mile. Compare that not only to a stock '99
Prowler (0-60 mph in 5.7 seconds, with a 14.3-second/95.4-mph quarter),
but more significantly to what we got a few years back from a '93 Dodge
Viper RT/10: 4.5 0-60, 13.2 at 112.1 mph in the quarter. In anybody's
book, the Hennessey Prowler GTX has plenty of "go fast" to accompany its
With the GTX, Hennessey focused totally on the straight-line
acceleration, so much that, in deference to Hennessey's customer's
tires, we didn't even run it through our
tests. The handling numbers in the accompanying chart are from a stock
Without the laughing gas, it's hard tell the GTX from a stock Prowler.
It feels marginally more muscular and, thanks to the headers and air
filter, slightly louder. Even when armed, the nitrous system is
transparent. The bottle heater automatically switches off when the
nitrous reaches the proper pressure, and no juice goes to the engine
until the throttle is flat to the floor. Drive sedately, and you can
leave the system armed all day. Even a partial lift off the accelerator
pedal immediately shuts off the gas.
Hennessey employed a Nitrous Express controller that permits virtually
infinite adjustment of the amount and timing of the nitrous delivery.
For our testing, the system delivered 100 percent of its capacity as
soon as wide-open throttle was reached. This required me to roll off the
line at part throttle to prevent speed-robbing wheelspin. But to avoid
spinning the huge 295/40ZR20
during street driving, you could choose to progressively ramp up nitrous
(If you thought "dental surgery" at the first mention of nitrous oxide,
here's a quick primer: Nitrous helps an engine produce more power
primarily by carrying more oxygen to the combustion chamber, which
allows the engine to burn more fuel. Also, when compressed nitrous oxide
expands, it cools the intake charge, which increases output potency.)
The twin, trunk-mounted 5-pound nitrous bottles-connected to the
manifold by steel-braided hoses-are good for about a half-dozen full
passes down the dragstrip or an evening's worth of
stoplight-to-stoplight sprints before they run dry.
In the "looks" department, Hennessey removed the bumpers, a move he says
is legal, at least in Texas. The rear mounting points were covered with
a roll pan. Up front, the turn signals were moved from the bumper to the
grille and small panels were fabricated to cover the bumper mounting
points. No suspension work was performed. The stock Goodyear Eagle GS-Ds
on stock wheels also were retained. Stickier, wider rear tires might
have chopped another tenth or two off the 0-60-mph time.
Total cost for the entire package is about $15,500 installed at
Hennessey's Houston, Texas, shops.
Our verdict: The Hennessey GTX package is a relatively easy,
relatively affordable way to give the Prowler some serious go-fast. And,
yes, I'm still grinning.
Hennessey Prowler GTX Specifications
||Front engine, rear-drive,two-door,
2-pass. hot rod
||60° V-6, SOHC, 4
||HMS Nitrous oxide
kit, HMS header and exhaust system, K&N air filter
Horsepower, hp @ rpm, SAE net
||365 @ 5000
|Torque, lb-ft @
rpm, SAE net
||450 @ 2800
||Goodyear Eagle GS-D
225/45VR17/295/40ZR20, stock aluminum
||Bumper deletion kit
| 0-30 mph
| 0-40 mph
| 0-50 mph
| 0-60 mph
| 0-70 mph
| 0-80 mph
| 0-90 mph
| 0-100 mph
|Standing quarter mile, sec/mph
|Braking, 60-0 mph, ft
|Lateral acceleration, g
Speed through 600-ft slalom, mph
|* from stock '99 Prowler