Anatomy of a Top Fuel Dragster
Below is the anatomy of a typcial Top Fuel Dragster, however all dragsters vary.
According to 2004 FIA regulations, a Top Fuel dragster must weigh no more than 2175 pounds (989kgs) after the run including the driver. The wheelbase must not exceed 300 inches (7.62 meters). From the front of the car to a point 12 inches (30.5cm) behind the center line of the front axle the car must maintain a minimum ground clearance of 3 inches (7.6cm). The top of the rear wing may not be higher than 90 inches (230cm) from ground level. The front overhang of the nose may not exceed 30 inches (76cm), measured from the center line of the front axle.
There are no computer controlled functions on the car at all but crews can log data such as exhaust temperatures, fuel pressure, fuel flow, crank shaft speed, rear axle speed and supercharger pressure to maximise the cars potential and help tune the cars performance on the next run. The cost is around £12,000.
An integral part of keeping a 7000bhp Top Fuel Dragster on the track at over 300mph in a time of just over 4.6 seconds is the massive rear wing and the front canard wings. The latest exert a down force of some 8000lpb for the rear and 1800lpbs for the front helping to adhere the vehicle to the track. Wing elements can be adjusted to different angles depending on the track conditions, atmospheric pressure and how the car is setup. The cost of a rear wing is approximately £5,000 with the front being around £1,500.
The engine is loosely based on the farmed 426 cubic inch Chrysler Hemi with a maximum displacement of 500c.i. with the billet aluminium block being supplied by several US manufacturers costing around £4,000 each. An engine that comes compete with billet aluminium heads, intake manifold, supercharger, fuel pump, magneto's and is ready to go costs approximately £60,000.
Sitting on top of the motor intake manifold is a mechanical belt driven device that literally rams air at a colossal rate into the engine. A typical supercharger turning at 11,000rpm will displace 110,000 cubic inches of air per minute.
4. Driver Safety Equipment
A complete multi layer fire resistant driving suit and gloves must be worn, together with state of the art crash helmet with fire resistant lining and neck cut off. Because of the G-forces exerted on the driver, the helmet is linked into the safety harness via a chinstrap. For the same reason a 360-degree neck collar and a Hans device is also worn to protect from whiplash should a high-speed crash occur. Drivers are secured in the cockpit with a five-point restraint system utilising a safety harness with 3 inch wide lap and shoulder belts which are covered with the fire resistant material. Arm restraints keep the arms inside the cockpit in the event of a roll over.
A multiple piece body formed of magnesium alloy and carbon fibre is attached to the chassis with quick release fasteners, commonly referred to as Dzus fasteners. The nose, rear wing, front wing assembly, kick outs and cockpit cover are usually all carbon fibre.
The Goodyear slicks on the back are 18.5 inches (47cm) wide and nearly 9.5 feet (3 meters) in circumference. Dependant upon track and atmospheric conditions, rear tyre pressure is between 6.5 and 7 pounds per square inch. Front tyres are 2.5 inches (6.25cm) wide and 22 inches (56cm) in diameter and are between 70 and 100psi.
7. Rolling Chassis
A Top Fuel chassis is fabricated from 300 feet of 4130 chrome moly tubing and costs approximately £40,000 complete.
8. Fuel System
Delivery of fuel to the engine is controlled by a pneumatically timed enrichment system, which runs in a parallel to the clutch control and ignitions systems. The volume of fuel increases in the line with the increase of clutch pressure to keep the fuel to air ratio correct for the amount of power that the engine needs to produce at any given point during the run. Put simply the engine does not need the same amount of fuel on the start line as it does 3 seconds onto the run. The power elixir that helps coax more than 13 horsepower from each of the engines 500 cubic inches is the fuel - nitromethane. Nitromethane is produced by the nitration or propane; the end result is CH3NO2. A maximum of 90% nitromethane is allowed under the rules with the other 10% being methanol. The mix can be less than 90% depending upon atmospheric conditions. Nitro is fed to the engine by a single four gear fuel pump that delivers between 85 and 100 US gallons (approx. 300 litres) per minute dependant on the crew chiefs set up. During warm up, burn out procedure and a quarter mile run, a typical Top Fueller will gulp 15 gallons (56 litres) of nitro costing around £35 per litre!
The big advance in performance in recent years has been due to more efficient magnetos. Modern magnetos are so powerful they have allowed greater amounts of fuel to be burnt efficiently, therefore increasing the power output of the engine. Coupled with this is the multiple advance and retard systems now available that allow the Crew Chief to change the timing of the ignition spark, either increasing of reducing power, to give optimum traction. The cost of these systems is approximately £10,000.
To prevent a loss of traction, power is transferred from the engine to the rear tyres via a complex timer controlled hydro-pneumatic clutch system. Centrifugal force on the clutch arms creates pressure on the five discs and four steel floater plates. The pressure is increased gradually in a series of minute stages. This involves a hydraulic ram, the speed of movement of which is controlled by a series of timed adjustable restrictors. The clutch will slip for approximately 3 seconds into the run until complete lock up with the engine and drive chain is achieved. This is not a computer-controlled function but is pre set before the run. Typically clutch temperatures can reach in excess of 1,000 degrees Fahrenheit. All Top Fuel cars run a standard rear gear ratio of 3.20:1.
The rear brake rotors measure approximately 11 inches (28cm) in diameter and are made from carbon fibre, activated via a hand lever in the cockpit and utilized only on the rear axle. The car's primary braking system is a pair of parachutes that can produce up to 6 negative G forces of stopping power. A direct opposite to the G forces felt by the driver at launch.
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