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Whereas in the United
States go-karts are generally dismissed as toys, in Europe
and South America they've long served as stepping-stones
to careers in auto racing. For many years, the preferred
model was a single-speed, direct-drive 100cc machine that
raced on special kart tracks that were much shorter and
twistier than auto-racing circuits. Karts with bigger
engines -- the first generation of superkarts -- were
introduced in Europe in 1969, but their popularity waned.
Then, about 15 years ago, in the never-ending quest for
speed, enterprising karters in southern California started
stuffing motocross engines and gearboxes into their
chassis. These 125cc shifter karts were such a hit that it
was just a matter of time before somebody decided that
bigger was bound to be even better.
But the twin-cylinder 250cc shifter karts that resulted
proved too powerful for kart tracks. Moving to full-size
car circuits was a no-brainer, but the higher speeds
achieved on these longer racetracks spotlighted several
deficiencies in existing kart chassis: The short wheelbase
made the machines diabolically twitchy, and their width
added scads of drag. As a result, the Commission
Internationale de Karting, based in Switzerland, developed
a formula for 250cc shifter karts designed to race on
automobile circuits, and the modern superkart was born.
Superkarts have longer wheelbases than conventional karts
(for better stability through high-speed corners) and
heavier minimum weights (to promote more robust chassis),
and they are narrower (to generate higher straight-line
speed).
In many respects, a superkart is a car writ small. One
fundamental difference is that superkarts don't have
springs to suspend the wheels or shock absorbers to dampen
them. Instead, the chassis serves as the suspension. While
a lot of racecars are built around carbon-fiber tubs
designed to minimize chassis flex, kart frames are still
welded together the old- fashioned way out of steel
tubing, because a certain amount of chassis flex is
required. Driver flex, too, is par for the course.
"One thing that makes the racing experience so exciting is
that you feel like you're part of the kart," says J.R.
Osborne, a 36-year-old real estate developer and
ex?Formula car racer who drove 26 hours straight from his
home in Denver to make the race at Laguna Seca. "The
downside is that karts are much more extreme than cars,
much more violent," he adds, referring to the formidable G
loads and molar-rattling vibration. "If the track is too
rough, you literally can't see."
The other big point of departure between automobiles and
superkarts is the powerplant. The four-stroke engine
technology that is found in virtually all street cars is
used mostly in slower karts. The hot setup is a two-stroke
engine. That's right, the annoyingly whiny, smelly, smoky
buzz-boxes that power many lawnmowers, chainsaws, dirt
bikes, even radio-controlled model airplanes. Two-strokes
spew out a lot of pollutants, suck down a lot of fuel, and
don't last very long. But they sure go like stink.
For example, Lawson's Yamaha TZ250 develops 90 horsepower
from a 250cc engine: That's 360 horsepower per liter. A
stock Corvette makes less horsepower -- 350 -- out of
close to 6 liters. Even Jeff Gordon's Nextel Cup stock car
produces only 130 or so horsepower per liter. And with the
Yamaha engine shoehorned into a container not much larger
than a breadbox, Lawson's superkart boasts a
power-to-weight ratio better than virtually every
production car in the world short of the $670,000 Ferrari
Enzo.
A two-stroke engine is less-is-more philosophy in motion.
A cylinder in a four-stroke requires two revolutions of
the crankshaft to complete its four distinct cycles --
intake, compression, combustion and exhaust. In
two-strokes, intake and compression are combined in one
cycle and combustion and exhaust in another, so each
cylinder produces power with every revolution of the
crank. Also, two-strokes don't have conventional intake
and exhaust valves, which means they don't need camshafts
to actuate a complicated (and often fragile) valvetrain.
Top-of-the-line superkarts are motivated by twin-cylinder
250cc two-strokes, some of which spin faster than 13,000
rpm. Typically, an extra carburetor jet enhances top-end
performance, while the exhaust port stays closed longer at
slower speeds to produce low-end grunt. Special attention
is paid to the shape of the exhaust pipe, which is
technically known as an expansion chamber. "You can put on
bigger carbs and you can run higher compression," says
longtime engine builder Sandy Rainey, Wayne's dad, "but
the pipes are where most of the power comes from."
Superkarts stop as well as they go, thanks to disc brakes
front and rear. (Frankel fabricates Lawson's rotors out of
an aluminum-based metal matrix compound to save weight.)
They also generate oodles of mechanical grip through wide,
treadless tires. Aerodynamically, though, superkarts are
relatively primitive, because the drivers must punch a
huge hole in the air. (Sure, you can run fully enveloping
bodywork, and some racers have, but that's problematic too
-- "It stiffens the chassis too much," says Paul Owens.)
Still, superkarts are very sensitive to aero tuning. The
standard practice is to adjust the nose of the kart,
lowering the ride height to increase downforce, and
balance the aerodynamics by trimming the angle of the rear
wing.
A good superkart costs about $15,000; figure 30 grand for
one with every option known to man. It ain't cheap,
obviously, but it's a bargain by motorsports standards. "I
hate to say it, but it comes down to ego," says Randy
Taylor, 47, an American Airlines Boeing 767 pilot who's
another car racer turned superkart fanatic. "If everybody
had zero ego, everybody would be racing superkarts."
Forty-nine superkarts stream onto the track Sunday
morning, forming what appears to be a long, multicolored
snake as they buzz around on their warm-up lap. By virtue
of winning yesterday's prelim, Lawson starts the race from
the pole -- the inside position of the front row. But when
he sees the green flag and floors the throttle, his Yamaha
sputters and his kart bogs down. (He finds out later that
the fuel line had come loose, allowing gasoline to spray
out.) White, a 125cc-shifter-kart ace, surprises everybody
by barging into the lead, and he, Lawson and Owens run in
feisty formation. Then Owens slices past both of his
rivals with a bold move, and White falls back as his
engine loses power.
Owens leads despite another gearbox problem. Lawson can't
take advantage because every time he buries the gas pedal,
his engine stumbles. He resorts to feathering the
throttle, which compromises acceleration and top-end
speed, so he makes up for it by pushing harder in the
corners. Racers often rate their effort in terms of
tenths, with nine-tenths being an aggressive race pace and
ten-tenths a banzai lap. As he and Owens scythe through
lapped traffic, Lawson's going eleven-tenths. At one
point, he draws alongside the Brit, but Owens hangs tough,
and Lawson can't make the pass stick.
With two laps to go, Lawson's kart runs out of gas and
rolls to a stop at the end of the front straight. By this
time, Payart is second, but he's too far behind to
challenge for the lead. Owens wins by 17 seconds. Back in
the paddock, he's hailed like a conquering hero. His
father hands him a cellphone; his brother is calling from
England to congratulate him. Owens pronounces himself well
satisfied. "Eddie Lawson has never ever been beaten --
until now," he says.
Over in the Lawson pit, the atmosphere is surprisingly
upbeat. Rainey is stoked after finishing fourth after a
race full of slicing and dicing. And Lawson is pleased
with his performance even though he's disappointed by the
result. "If I'd had a wide-open throttle, I think I would
have had (Owens) covered," he says. "After all, we were
quickest through the whole weekend. Then again, if my aunt
had balls, she'd be my uncle."
Owens may be king for a day, but Lawson's got nothing left
to prove. He's out here strictly for grins, and for a
racer, life doesn't get much better than Laguna Seca in a
superkart. "Try one yourself," he says, "and you'll know
what I mean." |