The following Stock/Super Stock horsepower changes were released December 16, 2024 produced by the Automatic Horsepower Factoring System (AHFS). This is the scheduled horsepower adjustment for this year. All changes are effective January 1, 2025. 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 one-time a year process when a 1.30 and under run is recorded during any NHRA event.
Any comments, thoughts, or requests must be sent to: AHFS@nhra.com or pcvengros@nhra.com
12/16/2024
Stock Horsepower Changes
Engine OEM NHRA New
Make CID HP HP HP Years Affected
Chev 262 140 157 161 1987 2.25%
Caprice Auto Trans
Chev 350 350 413 419 2013-2015 1.25%
Copo Auto Trans
Chev 327 250 249 253 1965 1.25%
Chevelle Auto Trans
Chev 350 160/170 273 282 1977-1978 3.25%
Nova Auto Trans
Chev 396 325 325 336 1967-1969 3.25%
Camaro Auto Trans
Chev 302 350 355 360 2022-2023 1.25%
Copo Auto Trans
Chev 327 390 390 395 2020 & 2023 1.25%
Copo Auto Trans
Chev 402 375 390 395 1970 1.25%
Nova Manual Trans
Chev 396 375 400 405 1968 & 1969 1.25%
Camaro Manual Trans Rep Heads
Chev 402 375 415 425 1970 2.25%
Nova Auto Trans OEM & Rep Heads
Pont 400 180 260 266 1977 2.25%
LeMans Auto Trans
Pont 350 160 273 282 1977-1978 3.25%
Ventura/Phoenix Auto Trans
Pont 400 225/230 275 279 1973-1974 1.25%
Firebird Auto Trans
Olds 350 160/170 273 282 1977-1978 3.25%
Omega Auto Trans
Mopar 360 160 289 296 1977 2.25%
Aspen – Volare Auto Trans
Dodge 426 460 466 472 2015 1.25%
Drag Pac Auto Trans
Ford 351 275 325 330 1972 1.25%
Mustang Auto Trans
Ford 428 335 388 397 1968-1970 2.25%
Mustang – Cougar – Shelby Auto Trans Rep Heads
Ford 302 565 581 595 2016 2.25%
Cobra Jet Auto Trans
Ford 302 122/137 146 150 1977 2.25%
Mustang Auto Trans
Note: See class guide for specific details. Updates highlighted in Yellow
12/16/2024
Super Stock Horsepower Changes
Engine OEM NHRA
Make CID HP HP New HP Years Affected
GM 305 various 265 269 83-87 1.25%
Camaro – Firebird Auto Trans
GM 305 various 235 241 88-92 2.25%
GT RWD Manual Trans OEM Heads
Ford 352 285 289 293 2010 1.25%
Cobra Jet Auto Trans
Chry 340 240 242 248 72-73 2.25%
Challenger – Cuda Auto Trans
Chev 327 300 294 301 63-65 2.25%
GT FWD Manual Trans Rep Heads
GM 305 various 253 259 88-92 2.25%
GT RWD Manual Trans Rep Heads
GM 350 various 292 296 88-89 1.25%
GT FWD Auto Trans Rep Heads
Pont 428 375 335 343 68 2.25%
GT FWD Auto Trans Rep Heads
Ford 428 335 360 365 68-69 1.25%
Mustang – Shelby – Cougar Auto Trans Rep Heads
Chev 396 390 395 404 2013-2015 2.25%
Copo Auto Trans
Chev 427 425 431 437 2012-2013 1.25%
Copo Auto Trans
Chev 427 430 436 442 2014-2015 1.25%
Copo Auto Trans
Chry 426 460 493 500 2015 1.25%
Drag Pac Auto Trans
Chry 354 530 557 570 2015 2.25%
Drag Pac Auto Trans
Chev 350 600 600 614 19-20,22-23 2.25%
Copo Auto Trans
Chev 350 630 630 645 19-20,22-23 2.25%
Copo Auto Trans
Chev 265 205 200 205 1956 Correction
Chev Auto Trans
Note: See class guide for specific details. Updates highlighted in Yellow
