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
