NHRA announces adjustments to the AHFS program

Automatic Horsepower Factoring System (AHFS)

The AHFS is used to review and evaluate runs in Stock and Super Stock for possible horsepower adjustments. The review for factor adjustments is conducted once per racing season. The data used during the review for possible reductions in hp is cumulative from the 1st National or Divisional event through the final National or Divisional event of the calendar year. Runs included in the AHFS database are limited to final qualifying runs (Q data) and all elimination runs (E data) at all NHRA National, Sports National and LODRS events. (At events where class eliminations are run, all class elimination runs are included in the AHFS database. Only the first round of class is part of qualifying and therefore is part of the "Q" database.) The "Q" data and "E" data files are the official data gathered by the NHRA timing system and processed through the NHRA Information Technology department. NHRA "Q" data and "E" data are the only data files used for the AHFS. No runs made during exempt events, National Opens, test and tune, time trials, 1/8th mile events or races within a race (i.e. Jegs Allstar eliminations, Stock / Super Stock Combos or other races that are not part of a season long points championship) are included in any review.  The following procedure is used in reviewing run data: Final qualifying, class eliminations, and elimination runs of 1.00 seconds or more, under the index, at NHRA National, Sports Nationals, and LODRS events will trigger a review. By definition, a trigger run is a run 1.00 second and quicker under the index. The engine family combination must make at least two trigger runs of 1.00 or quicker before a review is conducted to prevent a "one time fast run" from triggering a review. Trigger runs are not required to be in the same class. Multiple trigger runs can be made by the same car at the same event. The engine family combination being reviewed is put through two screenings as listed below. The screenings will look for an average of 0.850 and faster. Runs of .350 and slower are not included in the screening.

• 1st screening: The average for all vehicles running the particular engine family combination being reviewed is included in this screening. The review process will average runs in ALL classes TOGETHER with the same transmission type & the same body platform.

• 2nd screening: The average for all vehicles running the particular engine family combination being reviewed is included in this screening. The review process will average runs in ANY specific class SEPARATELY where there are ANY trigger runs.

• Parameters used for reviews:

1. Transmission type: Reviews made with manual transmission combination will be reviewed separately from automatic transmission combinations & visa-versa in Stock Eliminator. Reviews made with manual transmission combination will be reviewed separately from automatic transmission combinations & visa-versa in Super Stock Eliminator for those cars competing in section 12A (with the exception of SS/AH), 12B,& 12C. All other cars competing in sections 12D – 12G are averaged together with manual & automatic transmissions. 

2. Body platform: Both screening reviews are only in effect for the specific car model being evaluated. The body style is generally classified by the OEM auto manufacturers' definition of "platform", i.e., the Camaro and Firebird body are both based on the same platform and therefore considered the same with regard to body platform classification.

3. GT & base SS classes: GT classes will be separate from base SS combinations & visa-versa.

4. GT/FWD & GT/RWD: FWD bodies will be separate from RWD bodies & visa-versa.

• If the average in EITHER the 1st or 2nd screening is found to be 0.850 or faster, a change will be initiated.

• If the average in BOTH the 1st and 2nd screening is found to be 0.849 or slower, NO change will be initiated.

Adjustments are rounded up to the nearest full horsepower even if the fraction is below 0.5 horsepower. As an example, 2.15 horsepower is rounded to 3 horsepower. The quickest run, by the engine family being reviewed, is used to determine the adjustment percentage. Once the need for an adjustment is determined, the sliding-scale formula, based on a percentage of horsepower, is used to calculate the horsepower increase:

To decrease the potential for horsepower/index adjustments when favorable atmospheric (i.e. “mineshaft”) and/or track conditions may have contributed to extraordinary performance the NHRA has developed a system to protect the racers’ horsepower/indexes. If at the conclusion of qualifying the first competitor in the bottom half of the field is -.850 seconds or faster under the class index, in Super Stock or -.950 seconds under in the class index in Stock, the Q and E Data will not be used for the year-end review. This will only apply to qualified fields of 32 or more cars. Automatic changes due to runs of -1.20 or more under the respective index will still count at these events.

How to determine the top qualifier in the bottom half of a qualifying sheet.

If the qualifying sheet has an EVEN number of competitors:

Take the total number of qualifiers

Divide by 2.

Add 1

This will be the 1st qualifier in the bottom half of a qualifying sheet.

Example:

If there are 88 qualifiers:

88/2 = 44

44 + 1 = 45

The 45th qualifier is the 1st qualifier in the bottom half of a qualifying sheet.

If the qualifying sheet has an ODD number of competitors:

Take the total number of qualifiers

Add 1 to the total number of qualifiers.

This will result in an even number.

Divide by 2.

Add 1

This will be the 1st qualifier in the bottom half of a qualifying sheet.

Example:

If there are 87 qualifiers:

87 + 1 = 88

88/2 = 44

44 + 1 = 45

The 45th qualifier is the 1st qualifier in the bottom half of a qualifying sheet.

Once the need for an adjustment is determined, the following sliding-scale formula, based on a percentage of horsepower, is used to calculate the horsepower increase:

Under Index

Horsepower Increase

Index Change

1.000-1.099

1.25%

-.05

1.100-1.199

2.25%

-.10

1.200-1.249

3.25%

-.15  (immediate change)

1.250-1.299

4.25%

-.20 (immediate change)

1.300-1.349

5.25%

-.25 (immediate change)

1.350-1.399

6.25%

-.30 (immediate change)

1.400-1.449

7.25%

-.35 (immediate change)

1.450- 1.499

8.25%

-.40 (immediate change)