2025 4 CYLINDER RULES

Updated January 18th, 2025

Safety

  • Snell approved racing helmet within 5 years of manufacture date. (No motorcycle or DOT helmets.) SA2020+ Certification Recommended.
  • Full fire suit, gloves, and shoes made for racing.
  • Neck Rolls – OK
  • Head and neck restraint recommended.
  • Must have a fire extinguisher located within reach of driver.
  • Racing harness with up-to-date SFI rating is mandatory. Mounted in a safe manner to the cage.
  • Racing Seat and window net mandatory, both mounted solidly to the roll cage. Full containment seat recommended.

Roll cage 

  • Minimum of 4 point cage is mandatory, 6+ point cage suggested.
  • Minimum of three (3) Horizontal driver side door bars with a 24”x30”x1/8” steel plate mandatory.
  • Roll cage tubing will be 1-1/2”+ dia. X .095+ sidewall round tubing.
  • Must run at least 3 bars in front of driver; min 3/8” solid round bar.
  • May run strut tower side to side cross braces. 
  • Roll cage tubing connections MUST be welded around the entirety of each joint. Including on top of cage.

Chassis & Body 

  • Any front wheel drive OR REAR WHEEL DRIVE four-cylinder cars. No convertibles or AWD cars will be allowed. 4cyl Trucks allowed, no SUV’s. 4cyl Trucks must retain tailgates. 
  • Wheelbase may be no shorter than original OEM specifications. Rear steer is allowed.
  • Tube chassis – OK
  • OEM Doors must be welded or chained closed.
  • All OEM metal bumpers must be strapped or chained.
  • Must have tow chains at front and rear of car.
  • Radiator protection is Allowed.
  • All glass MUST be removed.
  • All flammable interior materials must be removed.
  • All exterior trim must be removed.
  • No rear-view mirrors.
  • Aftermarket style nose/tail pieces allowed. Any nose/tail piece used must be conformed to fit at reasonable and near-factory dimensions.
  • Aftermarket side skirts allowed. Aluminum skirts allowed.
  • No push bars to extend outside of bumpers or beyond nose piece.
  • All bumpers (stock or tubing) must be covered, no sharp edges may be exposed.
  • Sunroofs must be closed / covered with sheet metal.
  • Holes in firewall and floor should be covered in order to seal off driver from hot fluids or parts.
  • Stock firewall not required.
  • Driver and front passenger door window openings along with rear and front window openings must remain open and uncovered (No Polycarbonate/Lexan Windows.)
  • Front windshield visors allowed, no more than 8” in height.
  • Passenger side window visors allowed, no more than 4” in height and must run horizontal.
  • Small rear side windows can be closed or covered.
  • No fins, wings, flaps or lips are allowed anywhere on body, apart from a 4″ REAR spoiler.
  • Rear window louvers allowed.
  • Sheet metal decking, if installed, should remain flush with doors and should not create any lips, “Drop Decks” or airfoils.
  • Decking shrouds/rock guards no taller than 4.5” encompassing the driver for protection are allowed.
  • IF using OEM body “Trunk Lids” and rear hatches must remain on the vehicle. Fabricated rear “Deck Lids” will be allowed.
  • Hoods, trunks, and deck lids will be secured with quick release latches or hood pins.
  • Aluminum bodies – OK.

Weight 

  • 2,200 lbs. minimum weight with driver AFTER the race.
  • All added weight will be lead and painted white with your number clearly on it.

Gas Tank 

  • If stock gas tank is in front of the rear axle it may remain. Must have a skid plate. 
  • If stock gas tank is behind the rear axle, it must be replaced with a fuel cell located in the trunk. Minimum of four straps holding it in place.

Drivetrain 

  • Cars will use OEM four cylinder engine and transmission for make of car. (i.e.; GM-GM, Dodge-Dodge, Honda-Honda) 
  • Locked differentials are ALLOWED
  • No turbocharged, supercharged, multi-carbureted, rotary, or Cosworth engines.
  • Factory fuel injection or 2 barrel carburetor only.
  • Aftermarket/reprogrammed ECU/PCM ok.
  • Aftermarket/Milled throttle bodies ok. No Multiple TB or Velocity stack style.
  • Battery may be relocated. Must be in a waterproof box securely mounted.
  • No Nitrous
  • 2025: Pump Gas, Race Gas, E85, Methanol OK

Suspension

  • Camber: RF – No Limit, RR – 1”, Left side will remain stock. 
  • Stock and aftermarket coil-overs ok. 
  • May run aftermarket sway bars. 
  • Spring rubbers ok. 

Tires

  • Single side wall radial 300+ tread wear DOT tires maximum rating. No Z rated or better. 
  • No bias-ply, trailer tires, or recap tires.
  • 2025: No Racing Tires (Hoosier / American Racer, etc.)

Wheels

  • Stock or racing wheels ok. 
  • Maximum 7” wide. 
  • 2025: Beadlocks ok on all corners.
  • Any offset on right side ok. 
  • 3” offset on left side ok. 
  • 1” safety lug nuts recommended.