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
