ENGINES
THAT MAKE 7,000 HORSEPOWER
We take a close look into the
technology involved in Top Fuel racing, revealing some incredible
performances,
facts and figures – powered by major sponsors’ money, and computers
Today’s Top fuel dragster
can be the deepest money pit of all times or the most exhilarating drive you
could ever experience
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We explain some of the facts and figures that
will blow your mind and the three hundred
and seventy five thousand or so bucks
in that account to purchase your weekend car
A spare engine complete with blower and goodies can set you back in the region of $75,000
Typical running costs, allowing for fuel
and wear and tear on the tyres, clutch parts and engine innards such as valves,
pistons and bearings, will work out at approx $11,000 per run!
The mighty slicks, costing a thousand bucks
apiece, are good for maybe five hard passes.
Fuel costs are around $20 per gallon -15
gallons a round all to give that 7000 hp
Top Fuel racing is rocket science
Space – Launch = G-Forces
Did you know a Top Fuel Dragster will have a hit 300mph before
you finish reading this sentence?
Imagine you’re racing your ‘06 C6
corvette against a Top Fuel car over the quarter mile. You have the advantage
of a flying start and after shifting up through the gears you’re able to blast across
the start line, past the stationary fueler, at 200mph, at this moment; the
dragster launches and comes after you. Your foot is hard to the floor, you
hear an incredible brutal whine searing your eardrums and within seconds the
dragster has caught and passed you. No contest. You’ve lost.
From a standing start, the fueler has
covered the quarter mile in 4.5 seconds, with a terminal speed in excess of
300mph.
It reached 100mph in less than one second and by the eighth mile, or
660ft, the dragster was doing around 270mph. Its average acceleration was about
3,4 g, though in reaching 200mph well before half track, the initial figure was
closer to 5.5g. This is greater than a space –shuttle launch at 3g. On the
subject of G-forces, typical deceleration at the top end, courtesy of twin
chutes, is a retina -detaching 5g, the condition that led to the retirement of
the legendary “Big Daddy” Don Garlits from Top Fuel racing.
The current (backed up) NHRA Top Fuel
elapsed time record for the quarter mile is 4.428-seconds, set by Tony
Schumacher at the Auto Club Finals in 2006. A year earlier he attained the
fastest-ever Top Fuel terminal speed at 337.58mph. To achieve these figures the
engine has to peak at around 8,500rpm – a figure which comes from post-run data
readouts because the cars have no rev counters.
THOUSANDS OF HORSES seven to eight thousand horsepower
Top Fuel dragsters no longer run the likes
of ex-truck Dodge hemi engines rebuilt to racing spec.
Todays engines have 500 cubic-inches of scientifically-designed, aluminum-encased energy
that will kick-out more horsepower than can be mustered in total by the first
eight rows of NASCAR stockers at Daytona.
At seven to eight thousand horsepower = One thousand
horses per cylinder. Wow, that’s a whole prairie of Mustangs!
It’s said that a
stock hemi engine would not produce sufficient power to drive the fueler’s
supercharger, which requires
around 1,100hp, depending on the setup.
TWO GALLONS A SECOND? GULP!
Fuel consumption. Thought you wouldn’t ask.
Under full throttle, a Top Fuel car consumes two imperial gallons of 90 per
cent nitro-methane per second. This is comparable with the fuel burn of
a fully loaded Boeing 747, which with its four turbofan engines on take-off
power will gulp a couple of (imperial) gallons of Jet- A-1 every one and half
seconds. Incidentally, jet fuel creates about four times the energy of
nitro-methane, so that Jumbo’s “power pods” are pushing-out something in the
region of 32,000 shaft horsepower all together.
AN EAR BASHING UNEQUALLED
Don Garlits knows the score. He says
real fans don’t hear the fuelers with their ears,
they hear them with their
bones. “And their bones will still be shakin’ when their six feet under!”
Talking about shaking, the NHRA once had seismologists
out on the start line to record the effect of a pair of Top Fuelers launching.
Did the earth move for them? How about a measurement of 2.3 on the Richter
scale? So, not only can you hear those ground-pounding missiles with your
bones, you can feel them with the soles of your feet.
TYRES THAT GROW, AND CHANGE GEAR
A dragsters 17 inch wide, 36 inch diameter,
rear slicks grow taller by as much as 4½inches during a run due to centrifugal
force, hardly surprising since they operate with a pressure of just 4-5psi,
have to absorb around 4,500ft–lb of torque and will reach around 133
revolutions per second by the time the car goes through the timing traps at the
end of the strip. The tyres’ growth also acts as a constantly-changing final
drive ratio, in other words providing a higher ratio at the end of the run.
The “rotational inertia” of the tyres
delivers an enormous amount of down force on to the car. Because the wheel rim
spins faster that the tyre, this causes the sidewall to wrinkle at the bottom.
Once the slick “tread” reaches the rear part of the contact patch on the track,
it speeds up to catch up with the rest of the wheel rim. This momentum causes
great forces that are hugely responsible for the incredible launch-acceleration
times. After that, acceleration is down to engine torque. All very complex to
the uninitiated, but at least we can now understand why the slicks are screwed
to the wheel rims.
WINGS AND THINGS
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Three wings
are better than one!
Just ask
the Red Baron. He got there first, and that’s what counts in drag racing too.
We know dragster rear wings are there to keep the driving wheels in contact
with the track, but the primary purpose of
a front wing is to keep the car from pitching up and flipping over.
Because rear wings are mounted as far aft as possible, there is a tendency for
the front wheels to be lifted off the track surface due to weight transfer and
the drag of the wing. The front wing’s down force enables the driver to retain
directional control. However, its not just a matter of adding wings and saying
a prayer, the shape and structure of rear wings in particular…now mostly made
of carbon fibre or Kevlar… is a result of some very sophisticated scientific
calculation and research, including the involvement of NASA.
Experiments on
multi-element wings
by the
aviation industry many years ago….. including the UK’s Handley Page Company….. proved
they were more efficient at providing lift than single-element wings. Aircraft,
of course, need lift to fly, but dragsters want to hug the track, or dig in.
For this reason the dragster wing is mounted upside, creating down force or
“negative lift” The governing National Hot Rod Association has set rules and
limitations that must be met with regard to the type, size and position of rear
wings,
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which also must be locked in place so as to prevent any
potentially-dangerous adjustments during a run. In simple terms, aerodynamics
call for a wing providing maximum down force to be perhaps three feet wider
than used, but the NHRA limits the permitted surface area. The main reason the
span is kept to the width of the car or less is because id any part of the car
crosses the centerline, the driver is disqualified.
Eight tons of down force
state-of-the-art Top Fuel dragster wings
produce some eight tons of down force 330mph, which means in theory you could
run the car upside down in a tunnel… assuming you could get it up there in the
first place!! In the same way “winglets” on modern passenger airliners enable
them to improve fuel economy and extend
their range by tidying-up the disruptive airflow found at the end of a
conventional wing, the addition of endplates on dragster rear wings produces
vast improvements in the down-force-to-drag-ratio. Perfecting the exact shape
of the endplates came about largely due to the involvement and very serious
analysis by a NASA flight institute.
In conclusion, Top Fuel racing obviously
cannot be described as “Brute force and bloody ignorance” In truth, it’s almost
rocket science.
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