PLAYING BY THE RULES


As the quickest and fastest cars in nostalgia racing, it is a commonly held thought that the Top Fuel Dragsters must therefore be the least restricted. That the builders of these vehicles are free to seek speed in just about any manner they wish. Such is not the case.


The fact is that the front engine dragsters have many rules and restrictions placed upon them. More than most people realize. In order to increase your familiarization with our cars, and provide you with a short primer course about the rules under which they must be built and operate, we have assembled the following condensed (and highly unofficial) overview of NHRA’s Nostalgia Top Fuel Heritage Series rules. We believe that the more you understand about our cars, and the rules to which they must adhere, the more you will appreciate their performance.


CHASSIS: This class is reserved for front engine dragsters. That means the driver is located behind the engine and rear end as opposed to being in front of the engine as they are in the so-called ‘rear engine’ dragsters. The wheelbase can be no longer than 225 inches or shorter than 150 inches. The tubular chassis must be inspected yearly and certified as meeting stringent SFI specs.


ENGINE: The engine must be an American automotive-type V8 engine. The most popular engines in use today are replicas of the early Chrysler Hemi 392 cubic inch style engine. Also in use are derivatives of the late Chrysler Hemi 426 engine and the big and small block Chevrolet engines. Most of these engines use aftermarket aluminum blocks.


CUBIC INCH DISPLACEMENT: The engine can be no larger than 470 cubic inches. However, most engines in use today are well below that size.


WEIGHT PER CUBIC INCH: The car must weigh a minimum of 4.6 pounds for each cubic inch of engine displacement. As an example, if the engine size were 426 cubic inches, the car could weigh no less than 1959 pounds, including the driver, at the conclusion of a run. Most of the cars in competition today weigh in the neighborhood of 1975 pounds and the engine sizes generally range from high 300 to low 400 cubic inches in displacement.


CYLINDER HEADS: These cars can use alloy or billet cylinder heads, but they must retain the OEM bolt pattern and valve angles.


SUPERCHARGER: Must be a Roots-type supercharger. No centrifugal superchargers or turbochargers permitted. The supercharger’s rotor length and diameter are restricted to being no larger in size than that of a stock GMC 6-71 supercharger. The helix of the rotors must be the standard 60 degree design. No high helix rotors. Also regulated is the placement of the supercharger atop the engine. The supercharger can be driven no more than 14.99% faster than the engine speed.


FUEL INJECTOR: The opening of the fuel injector is limited to 65 square inches. Most cars use an Enderle or Hilborn fuel injector that was popular during the 1970’s.


FUEL PUMP: The volume of fuel available to the engine is used as one of the regulatory limits defining the horsepower capabilities of the engine. It is tightly restricted. These engines must use a single mechanical fuel pump that is available from one of several approved suppliers. It must be driven at ½ the crankshaft speed. All pumps must be tested by an authorized test facility to insure that it will deliver no more than 20.0 gallons of fuel per minute when driven at 4000 RPM pump speed and flowed through a 0.300” orifice. Each pump is sealed for certification after it passes inspection. No electronic, pneumatic, or hydraulic devices can be used to control the fuel system.


IGNITION: is limited to a single magneto. Most cars will use the MSD 44 amp magneto. Any timing advance or retard changes must be performed by the driver. No electronic, pneumatic, or electronic controls permitted.


CLUTCH: The clutch can utilize no more than three discs. It must be manually operated by the driver. No clutch management systems are permitted.


TRANSMISSION: Direct drive only. Transmissions are not permitted. A reverser is required.


REAR END: The rear end is limited to a gear ratio of 3.90:1 or lower (numerically 3.90 or higher).


REAR TIRES: Another tightly controlled component of these cars is the rear tires. The tires must be an approved nostalgia spec tire from either Hoosier or M&H tires. The rule is intended to control the width and roll-out of the tires in an attempt to limit the traction capabilities and thereby the speed of the cars.


WINGS: In conjunction with the restriction on tire size, these cars are also limited on the amount of aerodynamic downforce that can be incorporated into the car to aid traction. The canards that are located in front of the rear tires can have no more than 450 square inches of surface area (per side), and the front wing can be no larger than 500 square inches. The location of the wings is also regulated.


BRAKES: Dual piston rear wheel brakes are mandatory. The rotors and pads must be carbon fiber material.


PARACHUTES: Dual parachutes are mandatory.


FUEL: The dragsters can use a mixture of Nitromethane and Methanol (Alcohol). The percentage of nitro is not limited. No other chemical power additives are allowed.


DATA RECORDERS: are permitted, but only for the purpose of gathering data. They cannot perform any computer-type functions on the car during a run.


FIRE EXTINGUISHER: Each car must carry a minimum 20 pound onboard fire extinguishing system.


SHUTOFF DEVICE: The car must be equipped with a NHRA approved shutoff device that is activated in the event of a backfires that ruptures the manifold burst panel. This device will shut off the fuel to the engine and deploy the parachutes in the event it is activated.


This, of course, is a condensed look at the rules as they apply to these cars. If you would like to read the complete official rules you can find them at http://www.nhra.net/2011/images/heritage/2011HeritageSeriesRulebook.pdf


If you have a greater interest in the AA/Fuel Dragsters, or a specific question about our cars, we invite you to forward your questions to us and we will attempt to answer them. We also encourage you to ask your questions directly to team members the next time you are attending one of our races. You will find that they are all willing to share their knowledge with you.






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