Category Objective

Street Prepared builds on the Street allowances to provide opportunities for vehicles with more extensive modifications that may not be suitable for public highway use

Category Values

Provide a level of modification which encompasses lower-prep category allowances plus a moderate level of fabrication and a greater range of bolt-on alternatives

Core Modifications

• DOT R-compound tires
• Permanent alteration to the body, such as modification of fenders via cutting and/or flaring for tire clearance
• Drilling trunks/hatches for spoiler mounting
• Front splitters and rear spoilers
• Update/Backdate allowances to interchange of parts among selected models
• Engine tuning with stock internals
  • Aftermarket ECU
  • Unrestricted Induction
  • Emissions system removal
  • Unrestricted exhaust systems
• Weight reduction (A/C removal, steering wheel airbag removal, etc.)
• Suspension Updates

Subclasses

Your subclass should be highlighted

• Super Street Prepared (SSP) - High Performance sports cars, AWD turbo sedans, highest performance muscle cars and foreign grand touring cars
• C Street Prepared (CSP) – Lower and medium powered 2 seat and 2+2 sports cars and FWD cars
• D Street Prepared (DSP) – Heavier RWD sports sedans/coupes and FWD cars, medium perfromance 2-seater and 2+2 sports cars
• E Street Prepared (ESP) – Muscle cars and foreign grand touring cars
• F Street Prepared (FSP) – FWD cars with some lower power RWD and AWD cars

Authorized Modifications

• All Allowable modifications permitted in Section 13, Street Category are allowed
• Street Prepared vehicles may only be modified in excess of Street Category rules in the following ways. Any modification not specifically authorized by the Street Category or Street Prepared rules is prohibited. No unauthorized modifications are permitted in order to accommodate authorized modifications (e.g., non-standard hood scoops or holes necessary for carburetor clearance). Structural modifications, such as the addition of members known as "jacking rails," are not permitted unless specifically authorized herein
• Full Prep: Equipment and/or specifications may be exchanged between different years and models of a vehicle if:
  • The item is standard on the year/model from which it was taken, and
  • The years/models are listed on the same line of Appendix A, Street Prepared Classes
  The updated/backdated part or the part to which it is to be attached may not be altered, modified, machined, welded, or otherwise changed to facilitate the updating/backdating allowance. Standard factory installation methods, locations, and configurations are allowed. The updating and/or backdating of engines, transmissions, transaxles, and/or unibodies must be done as a unit; component parts and specifications of these units may not be interchanged. Cars not listed in the Street Prepared Sections of Appendix A may not be updated/backdated until approved by the SEB and published in the official SCCA® publication.
• Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed.
• Air conditioning systems may be removed in whole or in part. This rule should not be interpreted to allow modification of the heater system.
• On all forms of suspension, camber/caster adjustment within factory specifications may be achieved by the use of shims or eccentric bushings. The intent of this allowance is to permit cars to be restored to within factory-allowed specification ranges, not to provide an additional method beyond those permitted in Section 15.8, Suspension, to obtain alignment settings beyond the factory specifications. Refer to Appendix F for past clarifications of these rules

15.1 AUTHORIZED MODIFICATIONS

A. All Allowable modifications permitted in Section 13, Street Category are allowed.

B. Street Prepared vehicles may only be modified in excess of Street Category rules in the following ways. Any modification not specifically authorized by the Street Category or Street Prepared rules is prohibited. No unauthorized modifications are permitted in order to accommodate authorized modifications (e.g., non-standard hood scoops or holes necessary for carburetor clearance). Structural modifications, such as the addition of members known as "jacking rails," are not permitted unless specifically authorized herein.

C. Full Prep:
Equipment and/or specifications may be exchanged between different years and models of a vehicle if:

1. The item is standard on the year/model from which it was taken, and

2. The years/models are listed on the same line of Appendix A, Street Prepared Classes. The updated/backdated part or the part to which it is to be attached may not be altered, modified, machined, welded, or otherwise changed to facilitate the updating/backdating allowance. Standard factory installation methods, locations, and configurations are allowed. The updating and/or backdating of engines, transmissions, transaxles, and/or unibodies must be done as a unit; component parts and specifications of these units may not be interchanged. Cars not listed in the Street Prepared Sections of Appendix A may not be updated/backdated until approved by the SEB and published in the official SCCA® publication.

D. Alternate computer control modules may be used whenever an equivalent change to the conventional system is allowed. For example, alternate computer module control of ignition settings or fuel injection is allowed.

E. Air conditioning systems may be removed in whole or in part. This rule should not be interpreted to allow modification of the heater system.

F. On all forms of suspension, camber/caster adjustment within factory specifications may be achieved by the use of shims or eccentric bushings. The intent of this allowance is to permit cars to be restored to within factory-allowed specification ranges, not to provide an additional method beyond those permitted in Section 15.8, Suspension, to obtain alignment settings beyond the factory specifications. Refer to Appendix F for past clarifications of these rules.

15.2 BODYWORK Vehicles may only exceed the allowances of Street Category section 13.2 as specified herein.

A. Full Prep:
Fenders and bumpers may be modified for tire clearance. This includes the portion of a hood which serves as a fender/wheel well, where applicable. This does not permit modifications to the chassis or bodywork inboard of the vertical plane of the hub/wheel mounting face (at rest, with front wheels straight ahead). Flares may be added although tires may extend beyond the bodywork. Replacement of complete hood, flared fenders, or quarter panels is prohibited. Plastic and rubber wheel well splash shields may be modified or removed for tire clearance and for installation of fender flares as allowed herein. Hardware may be added to the steering system outside the passenger compartment to limit steering travel, provided it does not alter steering or suspension geometry within the limited range of motion and serves no other purpose. Limited Prep:
Fenders may not be cut or flared but the inside lip may be rolled to gain additional tire clearance. (The outer fender contour may not be changed.) Plastic and rubber wheel well splash shields may be modified for tire clearance and to accommodate a rolled inside fender lip. The modifications may serve no other purpose (e.g., air intake, brake ducts, etc.). No other changes to the standard fenders or wheel wells are permitted.

B. Factory rub strips, emblems, mud flaps, rear wings, and/or spoilers may be removed.

C. Strut bars (per Section 12.18) are permitted with all types of suspensions, subject to the following constraints:

1. A 2-point strut bar may be added, removed, modified, or substituted, but only with another two-point strut bar.

2. A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (i.e., firewall, bulkhead) must be in the standard location.

3. Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within two inches (2", 50.8 mm) in any direction of the actual suspension attachment to the chassis.

4. Except for standard parts, no connections to other components are permitted. Additional holes may be drilled for mounting bolts. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.

D. Full Prep:
Subframe mount bushings may be replaced, but must attach in the standard location(s) without additional modification or changes. Subframe position may not be changed.

E. Longitudinal (fore-aft) subframe connectors (SFCs) are permitted with the following restrictions:

1. They must only connect previously unconnected boxed frame rails on unibody vehicles.

2. Each SFC must attach at no more than three points on the unibody (e.g., front, rear, and one point in between such as a seat mount brace or rocker box brace).

3. Full Prep:
SFCs must be bolted or welded, but welding must be to the OE subframe stampings, not to the floor pan in between. Limited Prep:
SFCs must be bolted.

4. No cutting of OE subframes or floorpan stampings is permitted. Drilling is permitted for mounting bolts only.

5. No cross-car/lateral/triangulated connections directly between the driver’s side and passenger’s side SFCs are permitted. Connections to OE components such as tunnel braces or closure panels via bolts are allowed and count as the third point of attachment. No alteration to the OE components is permitted.

6. SFCs may not be used to attach other components (including but not limited to torque arm front mounts or driveshaft loops) and may serve no other purpose.

F. The driver and front passenger seats may be replaced with the following restrictions:
Seats must be securely mounted per Section 3.3.3.B.3. The seating surface must be fully upholstered. Any replacement seat must be a full back, bucket-type automobile seat incorporating a functional headrest. Kart seats, low-back dune buggy seats, and other simi lar types of seat are expressly prohibited. Cars may have no fewer than the standard number of seats. The seat tracks are considered part of the seat and may be substituted. Alternate seat tracks may serve no other purpose. The standard seat belts may be removed to facilitate the installation of alternate restraints complying with safety requirements. An alternate seat which replaces an airbag-equipped seat is not required to have an airbag.

G. Any steering wheel may be used. An alternate wheel which replaces an airbag-equipped wheel is not required to have an airbag. An alternate wheel is not required to have a horn button.

H. Airbags may be electrically disabled but not removed unless explicitly allowed.

I. Full Prep:
Spoilers/splitters and cosmetic trim pieces are permitted. Side skirts may not be used. Spoilers/splitters must comply with the following:

1. A spoiler/splitter may be added to the front of the car below the bumper. It may not extend rearward beyond the front most part of the front wheel well openings, and may not block normal grille or other openings, or obstruct lights. Splitters may not protrude beyond the bumper as viewed from above. Openings may not be used for the purpose of ducting air to the radiator or oil cooler, but they may allow air to flow through a permitted oil cooler provided no ducting is used. The spoiler may not function as a wing. This allows a vertical air dam/spoiler above a horizontal splitter, but splitter fences or longitudinal vertical members that serve to trap air on top of the splitter by preventing it from flowing around the sides of the car are not allowed.

2. A spoiler may be added to the rear of the car provided it complies with either of the following:
a. It is a production rear spoiler which is standard or optional equipment of a US model of the vehicle or an exact replica in an alternate material. b. It is a non-production rear spoiler which is mounted to the rearmost portion of the rear hatch, deck, trunk lid, or bodywork. The spoiler may extend no more than 10" (254 mm) from the original bodywork in any direction. Alternatively, in a hatchback, the spoiler may be mounted to the rear hatch lid at or near the top of the hatch; in such a configuration the spoiler may extend no more than 4" (101.6 mm) from the original bodywork in any direction. The spoiler shall not protrude beyond the perimeter of the original bodywork as viewed from above. The use of endplates is prohibited. Angle of attack is free. The spoiler may not function as a wing. Limited Prep:
Addition of spoilers, splitters, rear wings, bumper covers, valances, side skirts, and non-functional scoops/vents is allowed provided that either:

1. It is a production part which is standard or optional equipment of a US model of the vehicle. ("Model" is defined in Section 12.)

2. It is listed in the vehicle manufacturer’s US accessory catalog for that vehicle for normal highway use. This does not allow for parts sold through a manufacturer’s performance catalog (e.g., Ford Racing, HPD, MazdaSpeed, Mopar Performance, Mugen, NISMO, SPT, TRD, etc.). Parts must be installed as directed by the manufacturer. Exact replicas, including weight, from alternate sources are also permitted.

J. Rollover structures

1. Roll bars must comply with Section 13.2.G.1 in Street category.

2. Roll cages must comply with the following:
a. The roll cage need not be removable. It shall be bolted or welded to the car. b. The cage shall attach to the car at no more than 8 points, consisting of the basic cage with 6 attachment points and 2 additional optional braces. c. The forward part of the cage shall be mounted to the floor of the vehicle. If used, the 2 optional braces referred to in (2) shall be mounted, one on either side, from the forward section of the cage to the firewall or front fender wells. No braces shall pass through the front firewall. d. Roll cages that utilize NASCAR-style door bars that protrude into the door cavity must comply with the GCR roll cage requirements for production-based cars. e. Roll cages which utilize door bars that protrude into the door panel must comply with all Club Racing GCR requirements for roll cages. Installation of roll cages in Street Prepared cars must follow the same standards for interior modifications to accommodate the cage installation as those which are applicable to Touring cars in Club Racing.

K. Full Prep:
The use of a fuel cell which complies with GCR requirements is permitted, provided all of the following additional restrictions are met:

1. The capacity of the cell may differ by no more than 20% from that of the original tank.

2. The location of the cell may differ from that of the original tank by no more than 6" in any direction.

3. The car meets all applicable Club Racing Time Trials Level 3 Track Trials and/or Level 4 Hillclimbs safety standards, including those for rollover protection and the installation of a fire extinguisher.

L. Full Prep:
Fuel tank changes are permitted only as allowed under Sections 15.1.C and 15.2.K. No additional tanks or reservoirs may be used.

M.Accelerator, brake, and clutch pedals may utilize substitute covers of unrestricted origin, shape, and size provided they meet the following requirements:
covers must be securely attached, provide a non-slip surface, not interfere with each other’s operation, and must be deemed safe at Tech Inspection. A clutch pedal stop may be added.

N. Full Prep:
The OE radio may be removed. The OE sound system components, except wiring, may be removed. Any visible holes which result from the removal of such equipment must be covered.

O. Full Prep:
Sunroof-equipped cars may be converted to a solid-roof configuration provided a model without a sunroof is listed on the same line in Appendix A.

P. Full Prep:
A non-OE sunroof replacement panel may not be used in place of the OE sunroof.

Q. Fog lights may be removed.

R. Full Prep:
Interior rear view mirror and sun visors (and mounting hardware provided it serves no other purpose) may be removed or replaced.

S. Suspension and drivetrain mounting, including subframes, locations may be reinforced in order to improve durability and reliability. Any modifications are subject to the following restrictions:

1. Material may only be added, not removed.

2. Mounting locations may not be moved in any direction.

3. The method of attachment to other components may not be changed.

4. Any added material may not inhibit any motion that would otherwise be uninhibited.

5. Any modification must remain in the area of the attachment point to be reinforced. This does not allow for braces or cross connection between otherwise unconnected locations.

6. Modifications may serve no purpose other than to increase durability and reliability. This allowance is intended to improve durability without improving performance. Modifications are not to be made to allow for increased power or larger tires but to fix or prevent common failures of the vehicle structure or subframes. This rule is intended to permit modifications to prevent common failures such as suspension mounting location tear-outs or cracking shock towers/ subframes.

15.3 TIRES Tires must meet the requirements for Street Category with the exception of Sections 13.3.A.1 (minimum UTQG Treadwear Grade), 13.3.A.2 (minimum molded tread depth), and 13.3.A.5 (must be designed for highway use). The restriction that tires must be designed for highway use also does not apply; purpose-built DOT-approved competition tires are allowed. Section 13.3.C.4 is replaced with the following list, which may be altered at any time by the SEB upon notification of membership. • Kumho Ecsta W710

15.4 WHEELS Vehicles may only exceed the allowances of 13.4 as specified herein.

A. Wheels of any diameter, width, or offset may be used. Aftermarket wheels may be modified to install OE tire pressure sensors.

B. Wheel spacers are permitted. Wheel studs and knock-off wheel drive pegs may be changed in length and diameter. Wheel bolts may be replaced with studs and nuts.

15.5 SHOCK ABSORBERS/STRUTS Vehicles may only exceed the allowances of Section 13.5 as specified herein.

A. Shock absorber bump stops may be altered or removed.

B. On cars with lever-type shock absorbers, a tube-type shock absorber may be added. If the lever-type shock serves no other purpose, it must be removed. If the lever-type shock serves any other purpose, it must be retained.

C. Any shock absorbers may be used. Shock absorber mounting brackets which serve no other purpose may be altered, added or replaced provided that the attachment points on the body/frame/subframe/chassis/ suspension member are not altered. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). The system of attachment may be changed. The number of shock absorbers shall be the same as standard. No shock absorber may be capable of adjustment while the car is in motion unless fitted as original equipment. MacPherson strut equipped cars may substitute struts and/or may use any insert. This does not allow unauthorized changes in suspension geometry or changes in attachment points (e.g., affecting the position of the lower ball joint or spindle). It is intended to allow the strut length changes needed to accommodate permitted modifications which affect ride height and suspension travel. This allowance differs from the Club Racing Improved Touring Allowance 9.1.3.D.5.b.1.

D. On strut suspensions using a non-standard lower control arm (as defined by Section 15.8.H.2), an alternate upper spring perch/seat and/or mounting block (bearing mount) as described in Section 15.5.C may be used provided it offers no camber/caster adjustment beyond standard.

15.6 BRAKES Vehicles may only exceed the allowances of Section 13.6 as specified herein.

A. Full Prep:
Any brake line, master cylinder, vacuum brake booster, or brake proportioning valve that meets the requirements of Section

3.3.3.B.13 may be used. This does not allow multiple separate cylinders. A single master cylinder brace may be added provided it is bolt-on and serves no other purpose. One additional hole may be drilled in brake pedal arm for relocation of the master cylinder pushrod.

B. "Safety brakers" and units such as the "Brake Guard System" are permitted.

C. Full Prep:
ABS braking systems may be disabled, but not removed; brake boosters may be removed, modified, substituted, or added. Limited Prep:
Any brake line may be used.

D. Alternate brake rotors are permitted subject to the following restrictions:

1. Rotors must be ferrous metal except for standard parts. Aluminum rotor hats are allowed. Rotor dimensions (diameter and thickness) must be equal to or greater than standard parts. Cars originally equipped with solid (non-vented) rotors may utilize vented rotors.

2. Cross-drilled and/or slotted brake rotors may be used. Slots/holes are permitted only in the braking area of the rotor. Rotors featuring a drum-type parking brake in the hat area of the rotor may not be drilled or slotted in the parking brake area.

E. Drum brakes may be replaced with disc brakes. Disc brake rotors for such a conversion must be equal to or greater in diameter than the inside diameter of the standard brake drum. Changes to backing plates/ mounting brackets/brake lines to accommodate this change are permitted but may serve no other purpose. Drum-to-disc brake conversions must be bolted, not welded, to the axle/control arm/upright.

F. Air ducts may be fitted to the brakes provided that no changes are made in the body/structure for their use. They may serve no other purpose. Backing plates and dirt shields may be modified or removed.

G. A functional, redundant emergency (parking) brake must be present.

H. Brake calipers may be replaced, provided the number of pistons is equal to or greater than the original number of pistons. Caliper mounting brackets may be replaced to accommodate this change, but may serve no other purpose. Alternate caliper brackets must bolt to the original caliper bracket mounting location(s).

15.7 ANTI-ROLL (SWAY) BARS Vehicles may only exceed the allowances of Section 13.7 as specified herein. Substitution, addition, or removal of any anti-roll bar(s) is permitted. Bushing material, method of attachment, and locating points are unrestricted. This does not authorize removal of a welded-on part of a subframe to accommodate the installation, or the cutting of holes to route the bar or links. Non-standard lateral members which connect between the brackets for the bar, including allowed strut bars per Section 15.2.C, are permitted. The bar may serve no other purpose which is not explicitly permitted elsewhere herein. Components such as anti-roll bars and strut housings which serve dual purposes by also functioning as suspension locators may not be modified or substituted in ways which change the suspension geometry or steering geometry, and may not be installed in positions (e.g., upside down) other than that of the original configuration.

15.8 SUSPENSION Vehicles may only exceed the allowances of Section 13.8 as specified herein.

A. Ride height may only be altered by suspension adjustments, the use of spacing blocks, leaf spring shackles, torsion bar levers, or change or modification of springs or coil spring perches. This does not allow the use of spacers which alter suspension geometry such as those between the hub carrier and lower suspension arm. Springs must be of the same type as the original (coil, leaf, torsion bar, etc.) and except as noted herein, must use the original spring attachment points. This permits multiple springs as long as they use the original mount locations. Coil spring perches originally attached to struts or shock absorber bodies may be changed or altered and their position may be adjustable. Spacers are allowed above or below the spring.

B. Suspension bump stops may be altered or removed.

C. Suspension bushings may be replaced with bushings of any materials as long as they fit in the original location. Offset bushings may be used. Bushing type may be changed to alternate types (e.g. spherical bearing). Pins or keys may be used to prevent the rotation of alternate bushings but may serve no other purpose than that of retaining the bushing in the desired position. Differential mount bushings are not considered to be suspension bushings and are not covered by this allowance.

D. Differential mount bushings may be replaced but must attach in the factory location(s) without additional modification or changes. Differential position may not be changed.

E. Steering rack bushings may be replaced but must attach in the factory location(s) without additional modification or changes. Steering rack position may not be changed. Solid metal bushings are specifically prohibited. This does NOT allow shimming or otherwise relocating the steering rack.

F. The following allowances apply to strut-type suspensions:
Adjustable camber plates may be installed at the top of the strut and the original upper mounting holes may be slotted. The drilling of holes in order to perform the installation is permitted but the center clearance hole may not be modified. Any type of bearing or bushing may be used in the adjustable camber plate attachment to the strut. The installation may incorporate an alternate upper spring perch/seat and/or mounting block (bearing mount). Any ride height change resulting from installation of camber plates is allowed. Caster changes resulting from the use of camber plates are permitted.

G. Camber bolts may be installed providing these parts use the original, unmodified mounting points. Caster changes resulting from the use of camber bolts are permitted.

H. Camber kits, also known as camber compensators, may be installed. These kits consist of either adjustable length arms, arm mounts, or ball joints that provide a lateral adjustment to the effective length of a control arm. Alignment outside the factory specifications is allowed. Caster changes resulting from the use of camber kits are permitted. The following restrictions apply:

1. On double/unequal arm (e.g., wishbone, multi-link) suspensions, only the upper arms OR lower arms may be modified or replaced, but not both. Non-integral longitudinal arms that primarily control fore/aft wheel movement (e.g., trailing arm(s) or link(s) of a multilink suspension) may not be replaced, changed, or modified.

2. On arm-and-strut (MacPherson/Chapman) suspensions, the lower arms may be modified/replaced OR other methods of camber adjustment as allowed by Sections 15.8.C, F, or G may be used, but NOT both.

3. On swing or trailing arm suspensions, the main arms may not be modified or replaced but lateral locating links/arms may be modified or replaced.

4. The replacement arms or mounts must attach to the original standard mounting points. All bushings must meet the requirements of Section 15.8.C. Intermediate mounting points (e.g., shock/spring mounts) may not be moved or relocated on the arm, except as incidental to the camber adjustment. The knuckle/bearing housing/ spindle assembly cannot be modified or replaced.

5. Changes in suspension geometry are not allowed except as incidental to the effective arm length change. Note:
Many modern suspension designs known by other names actually function as double A-arm designs. These include the rear suspensions on 88+ Honda Civic/Integra, Dodge/Plymouth Neon, BMW E36, and most "multi-link" and are covered by Section 15.8.H.1.

I. Solid axle suspension allowances:

1. Addition or replacement of suspension stabilizers (linkage connecting the axle housing or De Dion to the chassis, which controls lateral suspension location) is permitted.

2. Traction bars or torque arms may be added or replaced.

3. A panhard rod may be added or replaced.

4. The upper arm(s) may be removed, replaced, or modified and the upper pickup points on the rear axle housing may be relocated.

5. The lower arms may be replaced or modified and the lower pickup points on the rear axle housing may be relocated.

6. Differential covers and attaching hardware may be replaced. Methods of attachment and attachment points are unrestricted, but may serve no other purpose (e.g., chassis stiffening). This does not authorize removal of a welded-on part of a subframe or bodywork to accommodate the installation.

J. On strut-equipped cars, the strut’s lower integral mounting bracket, for attachment to the upright or spindle, is unrestricted provided it attaches to the standard location. Any resulting change to the position of the strut centerline is allowed. Such brackets shall serve no other purpose. This does not allow for changes to the integral steering arm on cars that have the steering arm integrated with the strut body.

K. Changes in alignment parameters which result directly from the use of allowed components are permitted. For example, the dimensional changes resulting from the use of a cylindrical offset bushing which meets the restrictions of Section 15.8.C are allowed, including those resulting from a change in the pivoting action to

1. About the mounting bolt, or

2. About the bushing itself. Eccentric bolts are permitted for suspension adjustment only if they are as specified by the factory, per the last paragraph of Section 13.8.

L. Suspension components may be replaced with aftermarket components in order to improve durability and reliability. Any replaced components are subject to the following restrictions:

1. Replacement components may not be lighter than the original component.

2. Replacement components must install without modification to the mating part.

3. Replacement components may not differ from the original beyond improved strength, alternate manufacturing techniques, or replacement with larger components.

4. Components around or connected to the replaced component may not be relocated or modified unless permitted elsewhere in section 15.

5. Heat treatment may be used to increase the durability of an original part and the resulting part will be considered a replaced component.

6. Metal components may not be replaced with non-metal components. However a non-metal component may be replaced with a metal component so long as this does not violate other rules. For example the bushing metal content rule still applies.

7. Replaced components may not alter the suspension geometry unless otherwise permitted in section 15. Replacement hubs may relocate the wheel mating surface to widen the track width but may not relocate the wheel mating surface to narrow the track width.

8. Replaced components may serve no purpose other than to increase durability and reliability. This allowance is intended to improve durability without improving performance. Components are not to be replaced to allow for increased power or larger tires but to replace common component failures. For example, hubs often become wear items that require frequent replacement to avoid failure. Hubs may be replaced with larger, stronger hubs to reduce the chance of failure and increase the life of the component.

M.For cars originally equipped with transverse leaf springs, spring type may be changed to a coil spring. Spring perches may be added to shock absorbers for mounting coil springs in a "coilover" configuration.

15.9 ELECTRICAL SYSTEM Except for those with electric and hybrid powertrains, vehicles may only exceed the allowances of Section 13.9 as specified herein.

A. Any ignition setting, adjustment, or system may be used subject to the requirements of Section 15.10.D. This does not prohibit the use of "twostep" rev limiters used when the car is stationary.

B. The make, model number, and size of the battery may be changed but not its voltage.

C. Relocation of the battery or batteries is permitted but not into the passenger compartment. If the battery is relocated and the original battery tray can be removed by simply unbolting it, the tray may be removed or relocated with the battery. Holes may be drilled for mounting or passage of cables. Longer or shorter cables may be substituted to permit relocation. The number of battery or batteries may not be changed from standard. The area behind the rearmost seat is not considered to be within the passenger compartment. The area under the rearmost seat is considered to be within the passenger compartment.

D. Full Prep:
Any starter, generator, or alternator may be used in the original position. An alternator or generator must have an electrical output (including amperage) equal to or greater than the original equipment unit. Any generator or alternator pulley and belt of the same type as standard may be used (see Section 15.10.Y).

E. Wiring harnesses may not be removed in whole or in part. Wiring connectors for emissions control devices are considered part of the harness, not part of the emissions control system, and may not be removed. Connectors may be changed for compatibility with allowed aftermarket components such as ignition coils. Pigtails may be used.

F. A hole may be drilled in the firewall to permit passage of electrical wiring. It should be no larger than necessary and shall serve no other purpose.

15.10 ENGINE AND DRIVETRAIN Except for those with electric and hybrid powertrains, vehicles may only exceed the allowances of Section 13.10 as specified herein.

A. Engines must retain standard type lubricating system, but may have any oil pan (Accusump®-type systems allowed), oil pump and pickup, oil cooler(s), or oil or fuel filters. Fuel filters must be of automotive type and may serve no other purpose; a substituted fuel filter may not be used as a reservoir. Substituted fuel filters may not exceed one quart total capacity. A permitted oil cooler may be positioned in an opening in an allowed spoiler, provided no unauthorized modifications are made in order to perform the installation. Any power steering fluid cooler may be added.

B. Heat shields may be added.

C. Induction allowances are as follows:

1. Fuel injection systems and carburetors are unrestricted, including throttle bodies, manifolds, and plumbing/piping between the inlet port at the cylinder head and the atmosphere, subject to 15.10.C.4. Alternate throttle linkage and connections to facilitate installation of allowed induction systems are permitted but may serve no other purpose. If an induction system item is allowed to be removed and its original mounting bracket can be removed by simply unbolting it, the bracket may be removed as well.

2. Except for standard parts as defined in these rules, the external use while on course of liquids, ice, dry ice, refrigeration systems, vaporized compressed gases, etc. to reduce the temperature of the intake air charge is prohibited. Wrapping of intakes with liquid-soaked fabric is not permitted.

3. As utilized only on engines originally equipped with forced induction, induction charge heat exchangers (also known as "intercoolers" or "charge air coolers" [CACs]) are unrestricted in size and configuration. Air-to-air CACs and radiators for air-to-liquid CACs must be cooled only by the atmosphere except for standard parts. Body panels, fascias, or structural members may not be cut or altered to facilitate CAC installation.

4. Turbochargers and/or superchargers (forced induction) may not be added, changed, or modified (this does not allow ceramic coating of turbochargers). On vehicles originally equipped with forced induction:
a. No hardware changes or alterations to turbocharger(s) or supercharger(s), in size or number, are permitted. Turbochargers or superchargers may be updated/backdated only in conjunction with the accompanying complete engine unit. b. No changes are allowed to waste gate(s), number, or location. Wastegate openings may be modified by removing material to increase flow through the wastegate. No material may be added and no other modifications to the wastegate are authorized. This does not allow removal of any material to increase airflow into, through or out of the turbocharger’s turbine or compressor housings. No changes are allowed to variable-geometry turbine (VGT) hardware. c. Supercharger pulleys and belts of the same type as standard may be replaced with alternate pulleys allowing drive ratio changes. Belt tensioners may be added/changed to reduce belt slip. d. Compressor bypass valves (CBVs), blow-off valves, and pop-off valves are considered part of the air intake system and may be added, replaced, or updated/backdated independently of the other components of a forced induction system. e. Boost regulation systems, either electronic or mechanical, and electronic fuel cuts referencing boost pressure may be altered or modified except as prohibited herein. Boost pressure changes resulting from authorized changes are permitted.

D. Traction and/or stability control systems, as defined in Section 12.12, must be standard parts at standard settings or electronically disabled.

E. Air cleaner(s) may be changed or removed; velocity stacks may be added.

F. Emission control devices may be modified or removed. This permits the oil filler cap to be modified or substituted but does not allow valve covers or cam covers to be altered to install a breather or for any other purpose.

G. Intake water injection systems are allowed.

H. Fuel lines and pumps are unrestricted except as specified herein, as long as they do not pose a safety hazard. Fuel lines may be no larger than ½" (12.7 mm) i.d. (inside diameter) and may only connect to the original fuel tank or allowed fuel cell. They may be no longer than necessary for reasonable and safe installation, and may serve no other purpose. A single fuel feed line may be used. A single fuel return line may be used and a fitting for connecting it may be added at or near the top of the fuel tank. This does not authorize "cool-cans."

I. Exhaust manifolds and muffler systems are free, except that they must be quiet and terminate behind the driver (Section 3.3.3.B.16). Exhaust heat shields may be removed. Rear- and mid-engine cars without exhaust headers/manifold systems may use any exhaust system that meets the requirements of Section 3.5. This permits the removal of "heater boxes" in order to install headers on such cars.

J. Engine and transmission mounts may be replaced but must attach in the factory location(s) without additional modification or changes. Engine position may not be changed. Hydraulic shock type rear engine locators, or bobble struts, may be replaced by manufacturer’s performance part or aftermarket replacement part. This part must retain factory dimensions and attachment points, including factory design. (Example:
If factory locator/bobble strut is gas or hydraulic piston type, replacement part must be gas or hydraulic piston type.) If one or more non-OE engine or transmission mounts are used, Section 15.10.K does not apply and a torque suppression device may not be used.

K. One bolt-on torque suppression device may be used. A torque suppression device attaches from the engine to the body, frame, or subframe in one location and controls engine movement at that location along a single axis only. It may serve no other purpose. Examples of permitted devices:
• A chain • A rod with spherical bearings at each end Examples of devices not permitted:
• Any link which confines movement along more than one axis. • An engine mounting plate, or one or more plates rigidly bolted between the engine and the frame. Holes may be drilled to mount a torque suppression device. The installation may not include the welding of any plate(s) to the bodywork or to the motor mount(s) nor may it include multiple non-parallel links. If a torque suppression device is used, Section 15.10.J does not apply and replacement engine mounts may not be used.

L. Engine cooling radiators may be replaced with alternate parts subject to the following restrictions:

1. Radiator dimensions (width, height, thickness, etc.) must be no smaller than the standard part.

2. Radiator must mount to OE radiator mounts.

3. Fluid capacity and dry weight of the radiator must be no less than that of the standard part. Installation of an alternate radiator may serve no other purpose (e.g., to allow a cold air intake passage).

M.The engine fan and fan shroud (unless it serves another purpose, e.g., as an alternator/generator mount) may be removed, modified or replaced. Electrically driven fans are allowed. Flex fans are not allowed.

N. On two-cycle engines, the ports must be of standard heights, size and configuration; crankcase volume and reed plates must not be altered.

O. Full Prep:
Any metal clutch assembly, metal flywheel, or metal torque converter that uses the standard attachment to the crankshaft may be used. Non-metallic friction surfaces (e.g., clutch discs) are permitted. Dowel pins may be added. Any hydraulic clutch line may be used. Replacement or substitution of the clutch master cylinder and clutch slave cylinder is permitted. Limited Prep:
Any metal clutch assembly, metal flywheel, or metal torque converter that uses the standard attachment to the crankshaft may be used. Non-metallic friction surfaces (e.g., clutch disks) are permitted. Dowel pins may be added. Any hydraulic clutch line may be used. Replacement or substitution of the clutch slave cylinder is permitted. Clutch/Flywheel friction surface diameter must be the same as original equipment.

P. Any mechanical shift linkage may be used.

Q. Limited slip differentials are permitted. This permits locked differentials either by design, welding, or mechanical means. Differential cases, internal differential parts, and axle stubs may be machined as required for clearance and installation to the extent that material may only be removed, not added, and the exterior of the case may not be altered in any way. This machining may serve no other purpose. Any other modifications or substitutions to accommodate the installation of the limited slip differential must meet the requirements of Section 15.1.B and 15.1.C.

R. Full Prep:
Cylinders may be rebored to no more than 0.0472" (1.20 mm) over standard bore and the appropriate standard oversize piston may be substituted. This overbore dimension is an absolute limit; no additional tolerance is permitted to accommodate wear. Cast or forged, non-standard pistons of the same dimensions and configuration as original equipment pistons may be used. Additionally the replacement pistons must be of the same weight or greater as the original equipment pistons. Replacement pistons must match OE piston configuration exactly including quench area. The allowance for the use of aftermarket forgings vs. OE castings does not permit alternate piston dome designs. This allowance does not permit alternative ring configurations.

S. Full Prep:
Rotating and reciprocating parts may be balanced but not lightened.

T. Full Prep:
Intake and exhaust ports and manifold openings may be matched provided no change is made more than one inch from the port/ manifold interface. Material may be removed to facilitate port matching, but no material may be added.

U. Any transmission and/or differential oil coolers may be used. Differential covers may be modified or substituted for cooling.

V. The engine cylinder head(s) may be milled only to that amount specified in the manufacturer’s workshop manual. If no amount is specified then a maximum of 0.010" (0.254 mm) may be milled.

W.Axle/halfshaft and driveshaft retention/location devices may be installed for safety reasons to control the motion of attached shafts upon the failure of a coupling or universal joint. They may serve no other purpose. This allowance does not include "C-clip eliminators."

X. Any crankshaft damper or pulley may be used. SFI-rated dampers are recommended.

Y. Any accessory pulleys and belts of the same type (e.g., V-belt, serpentine) as standard may be used. This allowance applies to accessory pulleys only (e.g., alternator, water pump, power steering pump, and crankshaft drive pulleys). Alternate pulley materials may be used. Idler pulleys may be used for belt routing in place of items which the rules specifically allow to be removed such as smog pumps and air conditioning compressors. They may serve no other purpose.

Z. Camshafts and related parts must remain standard except that alternate cam drive pulleys or gears may be used to adjust cam timing if no variable cam and/or valve timing system exists as standard. Timing covers or valve covers may be altered for pulley clearance or access to adjustment. Type of cam drive (chain, belt, gear) must remain as standard. Alternate parts of the same general type (e.g., roller chain in place of "silent" chain) may be substituted. Mating parts (block, heads, covers, retainers, etc.) may not be altered except as mentioned above. Vehicles equipped with a variable cam and/or valve timing system as standard may use alternate computer calibration to adjust cam and/or valve timing but may not change or substitute cam drive components (hardware). AA. Upper engine shields made of plastic material, the purpose of which is to hide mechanical components in the engine compartment, may be removed if they have a solely aesthetic and/or acoustic function. BB. Cruise control systems may be removed in whole or part. CC. Engine oil tanks for dry sump lubrication systems may be replaced with alternate parts subject to the following restrictions:

1. Fluid capacity and dry weight of the oil tank must be no less than that of the standard part.

2. Oil tank must mount in the OE location. DD. Drivetrain components may be replaced with aftermarket components in order to improve durability and reliability. Any replaced components are subject to the following restrictions:

1. Replacement components may not be lighter than the original com ponent.

2. Replacement components must install without modification to the mating part.

3. Replacement components may not differ from the original beyond improved strength, alternate manufacturing techniques, or replacement with larger components.

4. Components around or connected to the replaced component may not be relocated or modified unless permitted elsewhere in section 15.

5. Internal engine components such as pistons, connecting rods, or valve train components may not be replaced under this rule.

6. Heat treatment may be used to increase the durability of an original part and the resulting part will be considered a replaced component.

7. Metal components may not be replaced with non-metal components. However a non-metal component may be replaced with a metal component.

8. Replaced components may serve no purpose other than to increase durability and reliability. This allowance is intended to improve durability without improving performance. Components are not to be replaced to allow for increased power or larger tires but to replace common component failures. For example, axle shafts or CV joints are often broken on launch. Under this rule these may be replaced with larger components or components made of stronger materials to avoid these breakages. Alternatively a vehicle may not replace a turbocharger with a larger or stronger part as this would increase the performance potential of the vehicle. EE. Cars with combustion chamber oil injection systems (such as those in rotary engines) may supplement the standard engine lubrication system with additional oil supplied through the standard fuel delivery system. FF. The Transmission Control Unit (TCU) may be re-programmed. This allowance only applies to modification of transmission behaviors and does not extend to re-programming any other components.

15.11 OUT-OF-PRODUCTION CARS Where a car is out of production and the manufacturer is either out of business, stocks no parts, or no longer has a required part, a part of any origin but as similar as possible to the original may be substituted. The entrant must be prepared to show documentary evidence that one of the three circumstances above applies and that the substituted part is as similar as possible under the circumstances. Substitute parts which provide improvements in performance (e.g., superior gearing, lighter weight, better camshaft profile) are not permitted under this allowance.