Remember the index I told you about? All cars must dial-in at or quicker than their class index. Once the eliminations start, it is run like a bracket race - with a few exceptions. In a 128 car field, it would be 1 vs 65, 2 vs 66, 3 vs 37 and so on, down to 64 vs 128. Once qualifying is complete, the ladder is set, using a standard sportsman ladder where the top half is matched against the bottom half. Nationals in Indianapolis, where everyone gets to run. The maximum number of cars that will qualify is 128, with the exception of the U.S. The further under that mark you can run in qualifying, the further up the qualifying sheet you will be. The AA/S Index is the quickest in Stock at 10.60, while the W/SA Index is 16.65. Originally designed to be an average of all the cars in that class in the country, now almost every car can run quicker than that Class Index, some as much than one-second under or more. When participation started dwindling, the Index system was developed. Many years ago, cars ran based off of the National Record for their class. Qualifying and Racing in Your Class IndexĬars qualify based on how far under their Class Index they can run. Leaded racing fuels are the only ones permitted, and there is an Accepted Fuel list and those are the only fuels legal in NHRA competition. Cars also have to pass a fuel check at the scales, to insure racers are not using any illegal additives to their fuel. In all cases, it is the “top” weight break of each class, multiplied by NHRA rating and add 170 pounds to determine the minimum weight each car must meet for each class it can run. ![]() My car, being a natural DF/S, can adjust weight to either make the “top” of DF/S, move up to CF/S, or move down to EF/S. In both cases, you would use the NHRA rating of the motor to determine classification – shipping weight divided by NHRA rating to determine the “natural” class of the car. ![]() It was factory rated at 375 NHRA rates it now at 350. An example of this is a 1967 Plymouth, with a 440 cid motor and a single four barrel carburetor. Some cars have been de-rated by NHRA, if they are not competive in the class that they would otherwise run. It now has a rating, by NHRA, of 364, and it now fits A/SA. For example, a 2002 Pontiac Firebird with an LS-1 346 motor started out with a factory rating of 310, and would have fit C/SA. In an attempt to keep the playing field level, NHRA will adjust certain combinations, which can in turn affect the class(es) a car can run. As stated above, most classes have many different brands competing in it. In some cases, NHRA will rate the engine higher or lower than the factory rating, to bring it in line with other cars in it’s class. If I cross the scales at less than 3,400, the run is disallowed if in qualifying, and I would be disqualified if it occurs during eliminations. From there, 170 pounds are added to each car, to arrive at the minimum Class Weight. I can move to the top of the class, which would be 19.00, multiplied by the NHRA rating for the motor, still being at 170. Using my car as an example, the weight break for it is 20.56, which puts it into DF/S, designed for cars with a weight/HP ratio between 19.00 and 24.99 pounds. Cars are permitted to move to the “top” of their class, or move up one class, or move down one class. All cars have a minimum weight they must meet at the scales, with driver. Once you find what class your car runs, you can determine the minimum weight for your car. Cars not listed in this Guide are not eligible for Stock Eliminator. NHRA publishes their Classification Guide on their website you can look up your car to see what class it can fit. W/S is for four cylinder cars only, with a weight to horsepower ratio of 24 or more. ![]() Cars with a shipping weight/horsepower ratio of 7.50-7.99 pounds will fall into AA/S. Some Mopar Hemis, 440’s and Max Wedges, big block 427 Fords, 427 and 396 Chevrolets, as well as some newer cars – LS-1 Firebirds, supercharged Cobra Jet Mustangs and the new DragPack Hemi Dodge Challengers are in this category. Classes run from AA/S and AA/SA (AA/Stock and AA/Stock Automatic) down to W/S and W/SA for rear wheel drive cars and trucks, plus five front wheel drive classes AF/S to EF/S.ĪA/Stock would be for the highest factory rated horsepower cars. All cars are classified this way, into one of 51 classes of Stock Eliminator. This will classify me into the DF/S ( D Front wheel drive/ Stock) class. It has a factory shipping weight of 3,444 pounds, and a factory horsepower rating of 170. I will use my car as an example, a 1992 Oldsmobile Toronado Trofeo. Calculating NHRA Spec Weight And ClassificationĪll cars are classified by using the factory shipping weight, divided by either advertised factory horsepower, or NHRA-rated HP.
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