Updated 2/2/26
OVERVIEW
The framework of the 2025-2026 Drag Illustrated Winter Series Rules and Regulations was proposed and agreed upon by series and event officials on October 1st, 2025.
The Drag Illustrated Winter Series strictly adheres to the safety and race procedure standards and guidelines of the National Hot Rod Association (NHRA). The 2025 NHRA Rulebook is available for download by clicking here.
PRO MOD
WEIGHT MINIMUMS
DUAL POWER ADDER TYPES PROHIBITED.
NITROUS OXIDE
- 2,300 lbs.
- 5.300-inch maximum bore spacing, 12.6-inch maximum deck height.
CENTRIFUGAL SUPERCHARGER
- Big Block Centrifugal Supercharger w/o Lock-Up – 2,645 lbs.
- Big Block Centrifugal Supercharger w/ Lock-Up – 2,670 lbs.
- The maximum specification for the compressor wheel tip to tip is limited to 140.99mm inducer diameter. Measurement will be taken at the point where the leading edge of the compressor wheel meets the inlet housing. All air entering the Supercharger must pass through a single inlet opening. Exducer backing plate and blade tip-to-tip dimensions may not exceed 188.99.
- Deduct 50 lbs. for ProCharger F3R-136. ProCharger F4X-136 not eligible for deduction.
- Add 25 lbs. for transmission with four (4) or more forward gears – all converter-driven combinations only. Addition does not apply to clutch combinations.
- It is required that all Centrifugal Supercharged entries have a ballistic blanket installed on the compressor housing.
- Any centrifugal supercharger or gear drive must be a commercially available production unit offered for immediate retail sale and delivery to the general public at least 21 days prior to the event. Test units, prototypes, experimental components, pre-production parts, or one-off designs are strictly prohibited. Prior approval from Competition Director required before use in the Drag Illustrated Winter Series.
ROOTS SUPERCHARGER
- Big Block Roots Supercharger w/o Lock-Up – 2,425 lbs.
- Big Block Roots Supercharger w/ Lock-Up – 2,460 lbs.
- Add 25 lbs. for transmission with four (4) or more forward gears – all converter-driven combinations only. Addition does not apply to clutch combinations.
SCREW SUPERCHARGER
- Big Block Screw Supercharger (C-Rotor, Max 92% O/D, w/o Lock-Up) – 2,635 lbs.
- Big Block Screw Supercharger (C-Rotor, Max 92% O/D, w/ Lock-Up) – 2,685 lbs.
- Add 25 lbs. for transmission with four (4) or more forward gears – all converter-driven combinations only. Addition does not apply to clutch combinations.
TURBOCHARGER
- Big Block Twin-Turbocharger (88mm w/o Lock-Up) – 2,610 lbs.
- Big Block Twin-Turbocharger (88mm w/ Lock-Up) – 2,685 lbs.
- Turbocharger must comply with the following measurements: Compressor 88 mm inducer – Turbine/Hot Side 113 x 125 – .312 maximum surge slot.
- Stepped compressor wheel prohibited (must be continuous contour of inducer to exducer.)
- Add 25 lbs. for transmission with four (4) or more forward gears – all converter-driven combinations only. Addition does not apply to clutch combinations.
- All turbochargers must have cross bolts in the exhaust to prevent the turbine from discharging in the event of a failure. Cross bolts are to be 3/8” grade 5 minimally and mounted within 1” of the turbine discharge flange.
- It is required that all turbochargers have ballistic compressor blankets installed on the compressor housings.
- Any turbocharger must be a commercially available production unit offered for immediate retail sale and delivery to the general public at least 21 days prior to the event. Test units, prototypes, experimental components, pre-production parts, or one-off designs are strictly prohibited. Prior approval from Competition Director required before use in the Drag Illustrated Winter Series.
6 CYLINDER
- Turbocharger (no restrictions) – 2,100 lbs.
- Nitrous Oxide – 2,200 lbs.
BODIES
- The following nostalgia body styles may deduct 50 lbs. from their minimum weight: 1937-1938 Chevy, 1937-1942 Willys, 1949-1950 Mercury, 1953- 1959 Studebaker, 1958 Plymouth Fury, 1953-1967 Corvette, 1955-1957 Chevrolet, 1955-1957 Buick, 1968-1972 Chevelle, 1970-1971 Plymouth Barracuda.
- Steel roof and quarter entries within 3 inches of factory wheelbase may deduct 35 lbs. (this will be measured on both driver and passenger side of the car and must be within the 3 inch maximum)
- Nostalgia and steel roof and quarter weight deductions cannot be combined.
Regardless of weight additions, no combination will be greater than 2,800 lbs.
FUEL
Racing gasoline and methanol permitted. The use of nitro methane, nitroparaphins and/or propylene oxide is strictly prohibited.
TIRES
Bias ply slicks only. Radial tire construction prohibited.
WHEELS
Wheels meeting SFI Spec 15.3 with beadlocks or liners mandatory. Maximum width of 18 inches as measured between inside edges of beadlock rings when bolted to wheel with tire dismounted, as shown in the diagram below. Liner wheels measured from inside lip to inside lip. Modification and/or lightening prohibited. Wheel discs or covers are prohibited.
