4 CYLINDER RULES
Paducah International Raceway has the final ruling on all questions of legality. A pre-race inspection will be
made to ensure SAFETY only. Questions of legality can and will be answered during a pre-race inspection if
requested by entrant. Legality will be determined in post-race inspection.
Full face helmet with Snell SA 2010 or FIA 8860-2010 certification or newer is required.
A head and neck restraint system (SFI 38.1 or higher) is strongly recommended. Certification date must be
within 5 years from date of SFI certification.
Minimum single-layer SFI 3.2/1 fire suit required (SFI 3.2A/5 recommended). Fireproof gloves SFI 3.3/1
4- or 5-point seat belt harness (SFI 16.1 (or higher) properly mounted per manufacturers’ specifications, is
required. Harness certifications must be within 4 years from date of SFI certification. Worn, abraded or torn
belts must be replaced.
Minimum 5 lb. fire extinguisher or on-board fire suppression system is strongly recommended securely
mounted within driver’s reach.
Commercially produced racing seats properly mounted per manufacturer’s specifications are allowed. A full
containment seat is strongly recommended.
Window nets of some type are mandatory.
Raceceiver is mandatory at all times on track. No two-way radios allowed.
Must be a commercially produced FWD or RWD car from a known manufacturer. No all-wheel drive or all
wheel steer cars. Engine must match car (ex. Honda must have Honda engine). 4 cylinder engines only; no
rotary engines. Engine must be stock, no porting or polishing. Headers are allowed.
Stock fuel injection or stock manufactured carburetor only. One 0.800″ throttle body spacer may be used.
Stock-type aftermarket and OEM throttle bodies are allowed. Must be stock air intake system. No cold air
intakes for fuel injections. A flexible rubber or plastic hose may be used in place of the stock air box tube.
Aftermarket radiators are allowed and can be braced for support.
Transmission, clutch or torque converter must be stock.
Stock ignition only. No super chargers, turbos or nitrous oxide.
Stock-type master cylinders required. No bias adjusters or shut-off valves. Brakes must remain stock-type and
operational to all 4 wheels. Aftermarket pads and rotors are allowed.
Any racing fuel or pump gas allowed.
Racing fuel cells are highly recommended. Fuel cell must be mounted per manufacturers recommendations
and must have a rollover valve. Fuel cells must have both a vertical and horizontal fire wall to separate from
the driver compartment.
The fuel rail may be aftermarket in the interest of safety. A fuel pressure regulator and/or gauge are allowed.
Fuel lines which run through the cockpit must be fully shielded with a firewall or within metal conduit.
Stock gas tanks must be securely mounted in rear of car and have a secure cap.
Exhaust which runs through the cockpit must be fully shielded from driver with metal. Exhaust pipes must not
extend out of any body surface more than 1” and pipe must be blunt and free of sharp edges.
Batteries must be securely attached inside engine compartment or may be relocated inside a securely
mounted box. Must use positive fasteners and hardware.
Max wheel width 8″. DOT tires only. Beadlocks allowed.
Chassis and suspension must be stock. Adjustable OEM components must be welded to render them non-
adjustable. Locked rear end or front end is allowed.
Stock STANDARD, non-adjustable, non-rebuildable shocks or struts required. No racing springs/shocks/struts
allowed. Springs rubbers are allowed. Springs may be swapped from other models but must be within 2” of
factory installed height. No aftermarket bump stops. No stacking of OEM bump stops.
Rear control arms must be stock but may be braced/strengthened/repaired. No adjustable control arms.
Stock type aftermarket suspension bushings are allowed. No weight jacks or cups of any kind
Suspension limiter chain or tether is allowed as a solid piece. No aftermarket limiters.
Body / Roll Cage:
Must have a fully welded, quality built MINIMUM 4-point roll cage with minimum of 0.95″ thick tubing. Roll
cage may extend forward behind bumpers. No part of the driver’s helmet may extend above the lower level of
the roll cage halo.
Minimum 3 driver door bars and 2 side door bars.
Gutting of body is allowed however car should maintain appearance of stock car. All window openings must
remain open and uncovered. All glass and unneeded plastic should be removed. No mirrors allowed.
No fins, wings, gurney flaps or lips are allowed anywhere on body. Spoilers must be stock for make/model.
No frame-like tubing may be added to chassis anywhere. No push bars may extend outside of bumpers. All
bumpers must be covered and no sharp edges exposed. No rub rails allowed on sides of body.
Sunroofs must be closed or covered with sheet metal. No holes are allowed in the hood and hood should
cover entire engine compartment. Holes in firewall and floor should be covered. Floor pans and/or firewalls
should remain intact between the front strut towers and rear strut towers. Firewalls and floor pans may be
patched with STEEL for REPAIRS only.