Open Wheel Modified
HUNTSVILLE SPEEDWAY OPEN WHEEL MODIFIED RULES 2024
RULE BOOK DISCLAIMER
The rules and/or regulations set forth herein are designed to provide
for the orderly conduct of racing events and to establish minimum
acceptable requirements for such events. These rules shall govern
the condition of all events, and by participating in these events, all
participants are deemed to have complied with these rules. NO
EXPRESSED OR IMPLIED WARRANTY OF SAFETY SHALL
RESULT FROM PUBLICATIONS OF OR COMPLIANCE WITH
THESE RULES AND OR REGULATIONS. They are intended as a
guide for the conduct of the sport and are in no way a guarantee
against injury or death to a participant, spectator or official.
The race director shall be empowered to permit reasonable and
appropriate deviation from any of the specifications herein or impose
any further restrictions that in his/her opinion do not alter the
minimum acceptable requirements. NO EXPRESSED OR IMPLIED
WARRANTY OF SAFETY SHALL RESULT FROM SUCH
ALTERATION OF SPECIFICATIONS. Any interpretation of deviation
of these rules is left to discretion of the officials. Their decision is final.
The Management of Huntsville Speedway
Warning! If you attempt to abuse the minimal amount
of rules set forth by Huntsville Speedway for the 2024
Open Wheel Modified Division, we will have no choice
but to refuse your request for participating. Just
because the rules don’t say you can’t, does not mean
that you can!
Refer to Huntsville Speedway’s General Rules for a full list of
rules regarding driver, pit and car safety.
- All starts and restarts will be mandatory double file,
second place car to the outside and so forth. No single file
restarts, even with 5 laps or less to go.
- Racing radios and neck restraints recommended.
- Wet or dry sump oil pump, block mounted filters only. No
tanks or coolers allowed.
- Aluminum engine heads allowed with no penalty.
- Cooling system may be modified; antifreeze shall not be
used. $250 fine.
- Only one carburetor allowed. No fuel injection on any
- Any V-8 American Cast iron engine block may be used as
long as rear of engine (bell housing flange) is mounted at
least 72” forward from the centerline of rear axle. Engine
offset must be kept within 2” of centerline of front cross
member. Minimum engine height will be 11” from ground to
front of center of crankshaft at a 4” frame height.
- No electric fuel pumps allowed.
- No external ignition crank triggers.
- No electronic traction control devices of any kind.
- 58% maximum left side weight.
- Minimum 2550 pounds, maximum 2800.
- Only 1 pound per lap fuel burn off allowed.
- All weight infraction penalties must be placed forward of
- Manual Transmissions only. Transmissions must have 2
forward and 1 reverse gears in working order.
- All transmissions must be clutch operated. Any driver
choosing to use a clutch larger than 7 ¼” must also use a
steel bellhousing. Flexplate must be SFI rated.
- No “in and out” gear boxes or automatic transmissions.
- Floater or quick change is allowed.
- No Wide Five hubs, no aluminum axle tubes.
- Drive shaft must be painted white.
Brakes, Wheels, and Tires
- Must run one brake per wheel. Single piston, steel caliper
- Add 5 lbs per aluminum single piston caliper.
- Add 10 lbs per multi piston caliper.
- Stock OEM size steel rotors only.
- 8” wide steel racing wheels only. No wheel weights of
any kind. No beadlocks. Air bleeders are allowed.
- Tire – American Racer KK704 only – must have
Huntsville Speedway stamp. (Subject to change for special
- OEM Factory production steel frames only. No sports car
frames. Frame must be fully intact on right hand side of
driver with factory specs -36” forward from centerline of rear
end housing. Front bumper horns may be removed in front
of steering gear box. No widening or narrowing of frame
allowed. Notching allowed for tie rod arm clearance, front
cross member may be notched and boxed for radiator
and/or steering clearance. Left side top frame rail can be
removed inside cockpit. Anything else will be subject to a
weight penalty, depending on the advantage you might have
over your competitors.
- Howe tube clips permitted. 50 lbs of total weight placed
forward of flywheel. Snout must meet Howe go/no-go
- Fuel cell cannot be any lower than rear axel housing and
mounted behind the rear axel. Must have a fuel cell
protector bar at least 1” lower than fuel cell frame.
- Minimum frame height at all times is 4”.
- Minimum wheelbase 108”.
- Aftermarket tubular upper control arms permitted.
Bottom control arms must be unaltered and in stock
location. NO aftermarket lower control arms permitted.
- No rack and pinion steering allowed.
- Front springs 5”minimum in diameter. Rear springs 4.5”
minimum in diameter. Minimum of 500 pounds front spring
- Stock passenger car spindles or fabricated spindles
allowed but must be steel.
- No internal or external bump stops, frame stops or
suspension limiters of any kind.
- Only non adjustable steel or Aluminum bodied shocks
permitted. 25 lb penalty for each adjustable shock. Penalty
must be forward of flywheel, additional penalties evaluated
with each win.
- Schrader valves permitted.
- Maximum overall track width shall not exceed 80” from
outside of the right side tire to outside of the left side tire
and will be measured at hub height.
- Only one rear spoiler allowed at a maximum of 8” height
and cannot be mounted past rear quarter panel or exceed
the width of the body. No side foils extending behind spoiler.
Total spoiler material is not to exceed 8” in height from rear
- Roof height must be minimum of 42” and maximum of
- Body sides must be straight front to rear, 120” maximum
length starting at the rear of engine block (bell housing
flange) on both sides of car.
- Maximum body width is 66”.
- Maximum body rake is 6” from lowest point on A post to
the rear spoiler lowest mounting location.
- Five Star style composite asphalt nose – Maximum width
of 43 1/2” not to be measured at chin spoiler.
Hand Fabricated nose – Maximum width of 43 ½”, two 2 ½”
fins allowed on both side end caps of nose. No other fins,
splitters, pans or ledges allowed anywhere, including body,
frame, suspension and fuel tank.
- 1/8” Polycarbonate/Lexan Windshield is highly
recommended. Full windshield is preferred.
- Refer to Huntsville Speedway’s General Rules for a full
list of rules regarding interior safety.