Safety Highlights
Safety in the pits and on track comes first. Drivers must wear full-coverage, multi-layer Nomex fire suits (SFI-rated), with fire-retardant underwear required for single-layer suits. Fire-retardant gloves and shoes are mandatory. Helmets must be full-face, Snell SA-2020 or newer, with an approved head-and-neck restraint system. Five-point harnesses (minimum 2" webbing) are required, mounted at shoulder height to the frame or cage; belts cannot be more than 3 years from the date on the SFI tag and are subject to inspection at all times. Cars must carry a compliant fire extinguisher, and all pit safety practices (proper clothing, eye protection, safe handling of flammables, jack stands, etc.) are enforced.
Car, Chassis & Body
Modifieds may use any make or model with any body style, but cars must have a stock-appearing roof (minimum 9 sq ft) with A-pillars covering the roll cage and attached to the windshield frame. A full hood must cover the engine and radiator. Rear wheels and flares cannot extend beyond nerf bars or scrub rails, and bodies must be complete at the start of each event. Roofs must be at least 38" high, measured 10" back from the windshield; left side window openings must be at least 13" high x 24" wide. Cars must be neat and presentable, with 20" x 4" numbers on both sides and the roof, plus a 4" nose number for line-ups. Spoilers must be Lexan, with a maximum 46" height from the ground and must remain see-through. The roll cage must follow all tubing, door bar, intrusion plate, and padding requirements, including a minimum of four door bars on the left side and three on the right, and a left-leg protection bar tied from the cage to the left front frame rail.
Engine, Ignition & Drivetrain
Modified engine, transmission, and rear-end configurations are tightly controlled. Manual transmissions must be OEM 3- or 4-speed units with all forward gears and reverse in working order; automatic transmissions must retain full shift patterns, use approved torque converters, and run with mandatory external oil coolers. Clutches, flywheels, and bellhousings must meet minimum weight and construction standards, with SFI-approved or equivalent scatter shields required. The rear axle must be a full-floater quick-change assembly with a full spool; no cambered axles or traction-control devices (mechanical, electronic, or otherwise) are allowed. Ignition systems must be 12-volt HEI, DUI, or MSD types with specific wiring requirements, Weather Pak connectors, open routing for inspection, and a soft-touch rev control mounted on the right side of the dash. No additional electrical devices or hidden wiring modifications are permitted.
Weights, Tires & Fuel
Weight rules vary by engine package but are centered around approximately 2600–2775 lb with a 60% maximum left-side weight. GM 602 and 604 crate engines and built engines each have their own minimum base weights; there is a 50 lb weight break for automatic transmissions. All ballast must be mounted above the frame rails, ahead of the fuel cell, in blocks of at least 10 lb, painted white and clearly marked with the car number, double-bolted, and tray-mounted if over 30 lb. Loss of ballast carries severe penalties. Wheels must be 15" diameter steel racing wheels with a maximum 10" width (measured bead-to-bead). The only approved tires are the American Racer AR153 spec tires in the listed 2026 sizes (27.0/10.0-15, 26.5/10.0-15, or 26.0/10.0-15). Tire altering or softening is illegal and will be monitored with durometers and other tools; tire inventory and registration procedures must be followed exactly, and running an unregistered tire can result in disqualification and loss of money and points.