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2017 Mid Year Stock, Super Stock Horsepower Adjustments Announced

The following Stock/Super Stock horsepower changes were released June 27, 2017 produced by the Automatic Horsepower Factoring System (AHFS). This is the first of two scheduled horsepower adjustments for this year. All changes are effective June 27, 2017. It should be noted that these changes include only results produced by the AHFS, and do not include written letters or requests. Those changes are listed separately.

        The AHFS is a program based on actual run data compiled from all available runs at NHRA events. The data-based format provides the ability to calculate average performances for any class and/or engine combination in Stock and Super Stock. The trigger point for the system is 1.00-second or more under the respective index, and must be produced on two different occasions. Engine-combination averages and class averages are then computed and analyzed to determine if a change is warranted. The amount of change is calculated on a stepped percentage basis. Where applicable, adjustments will be effective for the specific car model or body style being evaluated. An automatic adjustment is instituted outside the two-time a year process when a 1.20 and under run is recorded during any NHRA event.




                           Stock Horsepower Changes

Complete for 1st half rating period of 2017




Engine                   OEM          NHRA      New

Make          CID     HP            HP           HP           Years Affected


GM              231      200           203          206          95-02 Firebird,Camaro


Chev           350      350           367          372          13-15 COPO


Chev           350      530           588          602          14-15 COPO


Chev           396      390           430          436          13-15 COPO


Chev           454      365           365          374          1971 Corvette


Dodge         370      340           340          348          09-10 Challenger


Ford            281      235           275          282          2010 Cobra Jet


Ford            302      350           363          368          2014 Cobra Jet


Ford            302      133           149          154          1976 Maverick


Ford            330      450           549          562          2012 Cobra Jet


Ford            428      355           377          382          1967 Shelby


Olds            403      185           288          292          1977 Cutlass






Super Stock Horsepower Changes

Complete for 1st half rating period of 2017



Engine                   OEM          NHRA     

Make          CID     HP            HP           New HP  Years Affected



Chev           350      530           575          583          14-15 COPO


Ford            302      525           557          570          2014 Cobra Jet


Ford            330      435           516          523          2010 Cobra Jet