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2016 End of Year Stock, Super Stock Horsepower Adjustments Announced

The following Stock/Super Stock horsepower changes were released December 19, 2016 produced by the Automatic Horsepower Factoring System (AHFS). This is the second of two scheduled horsepower adjustments for this year. All changes are effective January 1, 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 national 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.

        Any comments, thoughts, or requests must be sent in writing to: National Hot Rod Association; Technical Department; attn: AHFS; P.O. Box 5555, Glendora, CA 91740; or e-mail, AHFS@nhra.com or pcvengros@nhra.com



Stock Horsepower Changes

Complete for 2nd half rating period of 2016




Engine                   OEM          NHRA      New

Make          CID     HP            HP           HP           Years Affected


Buick           350      175           262          266          73-74 Apollo


Chev           262      170           196          199          1996 S-10


Chev           283      220           223          226          1966 Chevy II


Chev           350      300           341          346          1992 Corvette*


Chev           350      530           575          588          14-15 COPO


Chev           396      390           420          430          13-15 COPO


Chev           409      450           450          461          2016 COPO


Chev           427      430           465          471          14-15 COPO


Chev           427      450           461          472          14-15 COPO


Dodge         345      305           337          342          09-10 Drag Pak


Mopar          426      425           450          456          1964 Belvedere


*= correction to match 93, 97-98




Super Stock Horsepower Changes

Complete for 2nd half rating period of 2016



Engine                   OEM          NHRA     

Make          CID     HP            HP           New HP  Years Affected


Dodge         426      450           456          462          09-10 Drag Pak


Dodge         426      460           482          493          2015 Drag Pak


Ford            330      435           504          516          2010 Cobra Jet