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IIRA Car Classes and Specifications

The following is a section from the 2004 IIRA Rules and Regulations
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A. General

Classification of cars will be in two (2) categories: Modified (Classes GTO, GTU, GTX,GTXlites) and Stock (Classes ST, SGT). Each category may have different rules regarding appearance, modifications, tires, etc. All cars are required to meet the general rules section. An adjusted engine displacement multiplier is used to determine class splits. Displacement will be derived by engine serial # or block markings. Engine or transmission insides are not protestable. Any car may be reclassified based on its performance at the discretion of the Rules Chairperson and IIRA Board.

Engine type___________Multiplier for original displacement

Rotary or 2 cycle ----------------------- 1.8
Turbo/Supercharged ------------------- 1.7
Four-Wheel Drive ---------------------- 1.3 (GTX and GTXlites only)
Pushrod ---------------------------------- 0.8
Three valves per cyl. ------------------- 1.1
Four valves per cyl. -------------------- 1.2
Variable cam timing -------------------- 1.1

Vehicles with more than one multiplier, ie 4x4, 4 valve 1600cc multiply the first total by the second multiplier ie. 1600x1.3=2080x1.2=2496cc.

B. Modified Category

1. Classifications

a. Class GTX - Unlimited engine, transmission, chassis. Must have full fender body. Roll cage is mandatory. Wings and spoilers are allowed but cannot extend beyond the perimeter of the car.

b. Class GTXlites -Same as GTX except engine adjusted displacement not to exceed 2000cc (see multiplier), and no NO2 allowed.

c. Class GTO - Those cars which 500 or more of that make and model were produced for street use. It is the responsibility of the entrant to prove eligibility. Suitable clear, plastic material may be substituted for all windows. Trunk lids, fenders, grills and hoods only may be of substitute material, but must be otherwise stock appearing. Floor may be modified for engine or trans. clearance, safety equipment or exhaust system clearance only. Wheel openings may be cut out only as required for tire clearance. Alternatively, fenders may be flared, but the original style wheel opening must be maintained. Spoilers and rear wings are allowed but cannot protrude the outside the perimeter of the car or in the rear be higher than the roof. Engine block must be stock appearing and available for that manufacture. No NO2 allowed.

d. Class GTU - Same as GTO apply except engine adjusted displacement not to exceed 1750cc see multiplier.

2. Specifications

a. Four-wheel hydraulic operated brakes must be operational.

b. No protruding, sharp objects. Cars must run stock appearing bumpers or no bumpers.

c. All batteries contained in driver's compartment must be completely enclosed and secured by a metal strap. Hot terminal must have insulating cover or be taped.

d. All cars must have substantial firewall between engine and driver.

e. A suitable bulkhead must be used between the driver and fuel tank, except when metal contained fuel cells are used. All fuel tanks/cells must be vented to the outside of the vehicle. Fuel lines inside driver compartment must be metal covered, and any refueling of the car (i.e. during Endurance Race) must be done with no one in the car unless equipped with a properly installed external filler with breakaway and check ball.

C. Stock Category

1. General

Cars of which 500 or more of that make and model were produced and available to the public in the U.S. as street-legal, production cars. Strictly stock, as delivered, with no modifications allowed unless listed below.

2. Classifications

a. SGT - Over 1750cc - under 3400 cc adjusted displacement.

b. ST - Under 1750cc adjusted displacement. (Exception: Saab 99 & 900 normally aspirated 2.0 liter and Dodge Omni/Plymouth Horizon normally aspirated 2.2 liter or less will be included in ST class.)

c. Class SR (Spec Racer) - Will conform to all safety rules and specifications of the IIRA.

3. Specifications

a. Exhaust is free and must exit behind the driver. System must be safely secured along entire length.

b. Any D.O.T. wheels allowed.

c. All SCCA IT modifications allowed.

d. Driver's seat is free. Passenger seat must be stock or the same as the driver's seat.

e. Rear seat may be removed. Loose items such as spare tire, jack, spare tire cover must be removed for safety reasons.

f. Steering wheel is free.

g. Air intake to air cleaner may be re-routed within the engine compartment.

h. An oil cooler and/or remote oil filter is allowed.

i. Accessory gauges are allowed.

j. Each competitor is required to have available a technical manual containing the specs for their car.

k. If fuel cell is used, refer to 2e. under Modified.

l. Wheel studs may be installed. Any wheel stud may not protrude past edge of rim.

m. Wheel diameter is open so long as wheels are D.O.T. approved. Different size brake components, such as calipers and/or rotors, may be used to fit 13, 14 or 15 inch diameter wheels.

n. Suspension is free but no modifications to suspension pick up points are allowed.

o. Air deflectors allowed for rear visibility.

p. All passive restraints must be disarmed, i.e. auto seat belts and air bags.

q. Carpet and headliner may be removed.

r. Headers will be allowed.


D. General Specifications

1. Roll cages are required in all vehicles competing in an IIRA event. Specific installations are subject to approval by the Chief Technical Inspector. It is permitted to modify interior door panels and trim pieces to accommodate installation of the roll cage. Trim items such as visors, arm rests and grab handles may be removed.

The basic purpose of the roll cage is to protect the driver if the car turns over and/or is rammed by another vehicle. It must be constructed to withstand compression forces from the weight of the vehicle coming down on the rollover structure and must prevent any intrusion into the driver's compartment. Forward braces and portions of the roll cage subject to contact by the driver must be padded with a non-resilient material.

Material, ERW, DOM - Seamless mild steel tubing or alloy steel tubing must be used (ERW tubing requires wall thickness of .120 inch).

a. All IMSA and SCCA legal cages are permitted.

b. Minimum material size:

Vehicle weight without driver_________Mild Steel_________Alloy Steel

Up to 1500---------------------------------1.375 x .095---------1.375 x .080
1500 to 2500-------------------------------1.500 x .095---------1.375 x .095
over 2500-----------------------------------1.500 x .120---------1.500 x .095
-----------------------------------------------1.750 x .095

An inspection hole, 3/16th inch diameter must be drilled in a non-critical area of the roll cage to facilitate verification of wall thickness.

c. Construction: The roll cage will consist of the main hoop with both a diagonal and horizontal brace, two rear down tubes, two front down tubes, a high front lateral tube connecting the front down tubes, two high fore-aft tubes from the main hoop connecting or contiguous with the front down tubes and two side door bars. It is permitted to supplement the structure with additional braces. The roll cage must be welded or bolted with backing plates at the points where the roll cage attaches to the vehicle.

Roll Cage Design:

Tubes represented by dotted lines are optional. NASCAR style door brace is highly recommended. Dual driver's side door bars are required.

2. No dual wheel cars allowed.

3. Four wheel drive cars allowed only in Class GTX and GTXlites.

4. All cars are required to have protective webbing located over driver's window or safety belt attached arm restraints. Nets must not be attached to the door.

5. Drivers of open cockpit cars must wear arm restraints and the roll cage must have the top covered with metal.

6. Securely mounted, metal-to-metal, quick release four-point mounted seat belt and shoulder harness mandatory. Three inch lap belts, two inch shoulder width minimum.

7. Fire extinguishers are mandatory in all cars. Extinguishers must be secured with a metal bracket and accessible to driver while seated in the driving position. Minimum size is 2-1/4 dry chemical (10BC rating) or equivalent. The extinguisher must have a gauge or current (6 month) test tag.

8. Car numbers must be IIRA approved decals on both doors, with class designation included at minimum of 5 inch height. A car number on the upper driver's side corner of the windshield is also required.

9. All cars must display appropriate series sponsor decals as required by IIRA series sponsors. Required decals must be displayed properly (right side up in full size). Decals, lettering or any identification that conflicts with IIRA series sponsors will not be allowed. Decals, lettering or any identification of sanctioning groups that compete with IIRA will not be allowed.

10. Head lights, tail lights and brake lights must be fully operational at tech inspection and one of each at the beginning of the race. One of each light must be operational at all times throughout the race, practice and qualifying. All tail lights shall have standard bulbs or bulbs of greater intensity. Auxiliary headlights are acceptable, mounted close to factory mounting point.

11. An amber or yellow quartz-halogen foul-weather light of 100W minimum, flood style not spot style, pointing rearward and mounted centrally on the outside of the car is mandatory. The light must be on while on the track and remain unobstructed throughout the race.

12. Must have inside and outside rear view mirrors.

13. Mandatory tow points in front and rear, marked with red paint or lettering. Must be easily connected to by tow truck operator.

14. Maximum length of car 190 inches.

15. Tires

a. Drive Wheels: Spec Tire as approved by IIRA Board of Directors as delivered with no modifications.

b. Non-drive Wheels: D.O.T. approved tires, Lindorfer style or Cam Am molded ice race tires and Lender style blank caps that are hand grooved and other pre-approved ice tire designs are permitted. All tires must have a tread pattern surface area greater than 28 sq. in./lineal ft. of tread. Any new design is welcome, but must be approved for use by the IIRA Board of Directors. Any tire must be (or have been) available to all competitors. Tire brand must be same as series tire sponsor or must be buffed off tire completely.

16. Studs

a. Drive Wheels: Spec studs as delivered in spec tire as allowed by IIRA Board of Directors with no modifications.

b. Non-drive Wheels: 28 studs/linear ft maximum.

17. There must be a restraining strap on all drive shafts of all front engine, rear drive cars.

18. All cars must have full windshields. Windshield wiper must be operational on driver's side of car at all times.

19. All cars must be neat appearing, mechanically and structurally sound with no protruding, sharp edges.

20. Both front doors must be operational from inside and outside.

21. No profanity or vulgarities may be displayed on race cars.

22. All cars must have a muffler as part of their exhaust system. Mufflers are required at all times during races.