SCCA Time Trials

Sport Category is intended to be for the lightly modified daily driver. Sport Category modifications should be generally available at retail performance outlets without having to "custom order" parts, and should be able to be installed by one person, in their driveway, using tools purchased at local hardware or home-improvement stores. This does not include additive or subtractive processes such as welding or removing material to create adjustment. Modifications should not need specialty tools or equipment to adjust or tune (e.g., scales).

Any allowed modification must be a direct-replacement part, using the same attachment points, type and number of fasteners and may not perform any function other than the original purpose of the part being replaced.

In keeping with a spirit of competition with comradery, entrants may be asked to declare specific brand and model numbers of modifications. SCCA shall be free to publish installed modifications.

Sport Category is a restricted ruleset. If a modification is not specifically authorized in these Rules, it is not allowed. (If it doesn't say you can, you can’t.)

1. Vehicles running in Sport, Tuner and Max Categories must meet Safety Level 1 Standards.

A. Roll bars, cages, racing harnesses and other safety equipment may be added, and must meet manufacturers' guidelines for installation. It is highly recommended that they at least meet the minimum for Safety Level 2 or Safety Level 3 Standards.

B. Nothing in the rules prevents you from adding safety equipment; the minimum amount of modification to install safety equipment is allowed.

C. To facilitate safety, vehicles that have an added roll bar (4-points) may remove carpet, seats and trim (including convertible tops) behind the front seats. Vehicles that have an added roll cage (6-points) may remove carpet, seats and trim (including convertible tops) other than the dash.

2. Fuel cells may be used in cars with the following restrictions and allowances:

A. Any replacement fuel cell should be constructed and installed to racing standards. (E.g., FIA/SFI approval, fuel cell enclosure, bladder, and foam baffling.)  

B. OE lines may be replaced in conjunction with a fuel cell provided they are shielded.

C. Any fuel lines—including gauge and vent lines—that pass into or through the driver/passenger compartment, shall be of steel tube or metal braided hoses or bulkheaded.

D. Drivers of cars with modified or replaced OE fuel lines or tanks must wear a suit, shoes, gloves and underwear as specified in SCCA Time Trials Safety Level 2 Standards.

E. Vehicles with modified or replaced OE fuel lines or tanks must have an on-board fire suppression (fire bottle or system) meeting SCCA Time Trials Safety Level 2 Standards.

F. Participants are cautioned that this is not an allowance to maximize fuel delivery by installing higher-performance parts than authorized by category rules. (E.g., installing an upgraded fuel pump if it's not otherwise allowed.)

1. To be eligible for Sport Category:

A. A minimum of 1,000 of that model must have been produced that model year for road use.

B. The vehicle must be capable of being licensed for normal road use in North America and delivered through the manufacturer's North American retail sales outlets.

The following items are guidelines for general repair and modifications in Sport and Tuner Categories:

A. Other than when necessary for safety enhancements, an authorized addition, modification, substitution or removal may not perform a prohibited function nor does it permit the addition, modification, substitution or removal of any other component unless it is specifically authorized.

B. Any part which becomes partially or completely detached during on-track sessions must be fixed and inspected by officials before that vehicle can return to the track. If the part is an aerodynamic addition, the part shall be completely removed for the remainder of the competition.

C. Parts (other than brakes and fluids) are not permitted to be replaced or changed after the car has passed tech inspection unless an Event Official has determined the part to be unsafe or broken badly enough that not changing it would keep the participant from the event.

D. Expendable replacement parts (e.g., bearings, seals, gaskets, filters, belts, bolts, bulbs, batteries, clutch discs, pressure plates, suspension bushings, drivetrain mounts, fenders, trim pieces, fuel filler caps, electrical sensors, etc.) may be used provided they are essentially identical to the standard parts (e.g., have the same type, size, hardness, weight, material, specifications, etc.), are used in the same location, and provide no performance benefit. These allowances are strictly to allow components to be replaced from alternate sources other than the original manufacturer. They should not be construed as an allowance to replace components with those which could be considered a “higher performance” alternative.

E. Any repairs must comply with factory-authorized methods and procedures, or industry standard methods, as follows: If the OE does not provide an appropriate method of repair, industry standard methods and procedures may be used. Such repairs may not result in a part or combination of parts that provides a competitive advantage (e.g., significant change to weight, suspension control, power, etc.) as compared to the standard part(s). Competitors are strongly cautioned to use this allowance to make common-sense repairs only. It is not permitted to use non-compliant parts even if they have been set to OE specifications.

F. Items which do not require the modification or replacement of existing parts and do not increase the peak performance of the vehicle are permitted. (E.g., a turbo or alternator blanket.)

G. Except for authorized modifications, other modifications or equipment will place the car in higher levels as appropriate. Configurations involving damaged parts (e.g., blown fuses) are not typically authorized by the manufacturer and hence are not allowed.

H. Vehicles may be street-driven cars, and SCCA does not encourage or condone the breaking of laws governing pollution control systems or the alteration of street-driven vehicles contrary to state and Federal laws regarding their use. It continues to be the responsibility of the individual to comply with such state and federal laws.

1. Accessories, gauges, indicators, lights and other appearance, comfort and convenience modifications including pedal cover kits, alternate shift knobs and paddles which have little or no effect on performance and/or handling and do not materially reduce the weight of the car are permitted. Delayed shutdown devices such as a “turbo timer,” which perform no function while the car is in motion, are permitted. This does permit the installation of an additional mirror (e.g., Wink®). The addition of small holes for attachment hardware for cosmetic modifications is implicit (e.g., holes for fasteners to mount additional gauges).

2. The driver and front passenger seats may be replaced with the following restrictions.

A. The seating surface must be fully upholstered.

B. The top of the seat, or an attached headrest, may not be below the center of the driver’s head.

C. The seat shall be securely mounted, so as to provide fore/aft and lateral support.

D. Passenger seat must be either OE or match the requirements for the driver’s seat.

3. Alternate steering wheels are allowed, provided the outside diameter is not changed by more than 1-inch from the standard size. Steering wheels with an integral airbag may not be changed unless Safety Levels 2 or 3 Standards are met.

4. Short shift kits which only change the length of the shift rod attached to the gear shift knob may be installed. Kits which change other linkage, mounting brackets and/or tension through springs are expressly disallowed.

5. A hole may be added to interior body panels, the engine compartment, the trunk, and/or a strut bar to provide access to the adjustment mechanism on a shock absorber. The hole may serve no other purpose and may not be added through the exterior body panels.

6. Any item that cannot be held permanently in place by factory-installed fasteners may be removed.

7. Spare tires, tools and jacks may be removed. Any fastening hardware and/or other pieces that can no longer be firmly secured in the absence of the spare tire may be removed, if necessary, to ensure compliance with safety inspection requirements.

8. Data acquisition systems (including video cameras) and the accompanying sensors are allowed but may serve no other purpose during a run than real-time display and data recording.

9. With the addition of Safety equipement, the following allowances apply:

A. If the vehicle is equipped with at least a 4-point roll bar, driver’s seat, and restraints meeting SCCA Time Trials Safety Level 2 Standards:

1. Rear seats carpet and trim behind the seats may be removed.

2. Sunroofs, moonroofs, and similar roof-mounted panel cartridges may be replaced by an alternate solid panel serving no other purpose. Attachment is unrestricted but must be secure.

3. Airbags may be removed.

4. Airbag-equipped steering wheels may be replaced or have the airbag removed.

5. Convertible soft tops and related structure and brackets may be removed.

B. If the vehicle is equipped with a minimum 6-point roll cage, driver’s seat and restraints meeting SCCA Time Trials Safety Level 3 Standards, all interior carpet, trim and passenger seats other than the factory dash may be removed.

1. Addition or removal of spoilers, splitters, spoilers, single-element rear wings, bumper covers, valances, side skirts, convertible hard tops and scoops/vents is allowed provided that:

A. The removal of parts matches a production model of that generation classed in Sport Category. (eg., You may not remove parts unless a model of that vehicle was available without the part or parts.)

B. It is a production part which is standard or optional equipment of a model of the vehicle classed in Sport Category.

C. It is listed in the vehicle manufacturer’s accessory catalog for that vehicle for normal highway use. This may not allow for parts sold through a manufacturer’s performance catalog (e.g., Ford Racing, HPD, Mazdaspeed, Mopar Performance, Mugen, NISMO, SPT, TRD, etc.).

D. All allowed parts must be installed as directed by the manufacturer. Exact replicas, including weight, from alternate sources are also permitted.

E. Updated parts, replacement parts, or any other changes by the manufacturer documented in the parts catalog or other manufacturer documentation as superseding the original part number used when manufactured are considered to be standard parts.

F. Wings and Spoilers are subject to the following restrictions unless the vehicle is in the same class:

1. The part may not be adjustable.

2. The unit (wing, supports and end plates) may not be constructed by more than three primary pieces. (E.g., a wing with separate wing element, end plates and supports as in a Cayman GT4 or Camaro ZL1 1LE would not be allowed on a lower-class Cayman or Camaro.)

2. Factory emblems, mud flaps, bolt-on front valance lips/spoilers and fog lights (except those integral to a headlight or turn signal) may be removed. Rear wings may be removed so long as the vehicle retains any federally-mandated third brake light.

3. Hood straps or fasteners may be added.

4. Cars may add one (1) rear trailer hitch. The resulting weight addition is allowed. The hitch may serve no other purpose. Factory tie downs and cosmetic pieces (e.g., diffusers) may be modified or removed to facilitate hitch installation. Complete or partial removal of the hitch is allowed for competition, provided it does not result in a reduction in weight compared to the unmodified standard configuration.

5. Tow bar brackets may be installed but may serve no other purpose.

6. Tow hooks and tie downs may be added, modified or replaced. Addition of tow hooks and tie downs are permitted, and location is unrestricted. Non-standard tow hooks shall serve no other function.

1. Any width or diameter wheel and wheel spacers may be used provided it complies with the following:

A. Non-metallic wheels must be certified/approved from an appropriate, recognized standards organization. (e.g., FIA, SFI, SAE, TUV, etc.)

B. Wheel spacers are permitted.

C. Wheel studs, lug nuts, valve stems (including pressure-relief types) and/or bolt length may be changed. Wheel bolts may be replaced with studs and nuts, but the number of fasteners may not be changed.

D. Tire pressure monitoring sensors may be removed.

E. Centerlock/spline drive/knock-off type hubs may be converted to lug-type hubs.

F. Aftermarket, accessory-catalog or non-standard OE wheels shall meet the minimum wheel weights determined by the following formula and multiplier.

Example: For a 15-inch diameter by 7.5-inch width (15x7.5) wheel: 15 + 7.5 = 22.5, then multiply 22.5 x 0.48 which = minimum weight of 10.8 lbs. for any 15x7.5-inch wheel.

Tires must meet the following requirements to be eligible for use in Sport Category. No tire model will be eligible for Time Trials competition until it meets all requirements of this section. Tire models not meeting the requirements by January 1st are not eligible for Time Trials competition until after the Time Trials National Championships of the year.

1. Specification

A. Minimum UTQG Treadwear Grade of 200.

B. Minimum molded tread depth of 7/32 inch as specified by the manufacturer.

C. Listed in a current year or prior two years of the “Tire Guide®” and/or the “Tread Design Guide®” (www.tireguides.com).

D. US Department of Transportation (DOT) approval.

E. Tires must be designed for highway use on passenger cars.

2. Eligibility Requirements:
The following are prerequisites before a tire can be used in competition at National Time Trials Events.

A. Tire availability: Tires are considered available when competitors can take possession through retail channels. Pre-orders are not considered available.

B. Tires must be equally available to all competitors. Tires that are in short supply do not specifically violate this section. Extensive shortages may result in the tire being placed on the exclusion list until supply is replenished. Tire variations differing from standard specification, delivered only on a limited basis, or only to selected competitors may not be used.

C. Tire models must have tires available in at least four (4) rim diameters and in at least six (6) sizes which meet these requirements.

D. Material Change: Tires which previously met the eligibility requirements that undergo a significant compound change, tread pattern change, or other significant redesign reset the requirement for eligibility described in this section.

E. A tire model which was previously allowed by these rules continues to be eligible for competition until specifically disallowed.

F. Reintroduction: Models that were once discontinued will be considered a new model once reintroduced and must meet all the requirements of this section.

3. Tire Size Limits
Tires are limited to the OE section width, or have a section width up to and including the following (mm):

Cars in Classes 2–6 and are otherwise legal for Sport Category may bump up classes based on tire size. Cars in Sport 1 with oversized tires will go into their vehicle appropriate Tuner Category class.

4. Tire Use

A. Scored Sessions
Unless a “wet session” is declared by event officials, vehicles must run on the same set of tires for all scored competition rounds, and the tires should be marked with a stamp on grid of the first competition. Tires may also be replaced at the discretion of the Technical Chief in cases safety issues such as damage or excessive wear. (Entrants are warned that damage caused by deliberate abusive handling or deliberate shaving should not be given a replacement allowance.)

B. Unscored Sessions
Vehicles are required to practice on tires which are legal for scored sessions in their class, but do not have to be the same set.

5. Other

A. Tires may be shaved evenly and parallel to the axis of rotation, but may not otherwise be siped, grooved or modified.

B. Tires must have a minimum tread depth of 2/32nds at two (2) points 180 degrees apart.

C. No recap and/or retread tires may be used.

D. Excluded tires: Tires may be excluded for, but not limited to, low volume production, extensive availability limitations and specialty design.

E. The tire must not appear on the following exclusion list, which may be altered at any time by the Time Trials Board (TTB) upon notification of membership.

- Kumho V720 ACR (less than minimum molded tread depth)

- Vitour Tempesta P1

1. The make and material of brake pad/shoe linings (friction material) may be changed.

2. Non-standard brake rotors may be used provided they are of equal or larger dimensions (diameter and thickness) and match the OE design and are constructed of the OE or heavier materials. Thickness includes the individual plates of a vented rotor, as well as the overall dimension. The diameter for replacement rotors is measured at the minimum outside dimension. Cross-drilled and/or slotted brake rotors may be fitted provided all such voids are within the disc area and comprise no more than 10% of that area.

3. Brake lines may be substituted with alternate DOT-approved flexible brake lines.

4. Alternate brake bleeder fittings (e.g., Speedbleeders®) are permitted. They may serve no other purpose.

5. Standard anti-lock braking systems (ABS) may be electrically disabled but may not be removed or altered in any other way.

6. Brake Rotors and Calipers may be swapped to OE option package configurations from the same model and generation of car, providing the rotor width and diameter are of equal or larger sizes and the number of caliper pistons is the equal or greater. The allowances from 1–5 also apply to option package swaps.

7. Air ducts may be fitted to the brakes and changes may be made to option-package lights, splash shields, backing plates, dirt shields and removable trim pieces to facilitate instillation and routing but not parts like bumper-covers. The intent is that altered parts are easily put back to “stock” or not cosmetically visible. Ducts or holes may serve no other purpose. Control arm mounted brake ducting, or air scoops, may also be fitted, providing they serve no other purpose.

The make of shock absorbers, struts and strut housings may be substituted providing that the number, type (e.g., tube, lever, etc.), system of attachment, material, design and attachment points are not altered, except as noted below. The interchange of gas and hydraulic shocks absorbers is permitted.

1. The shock may be OE or OE equivalent from other vehicles of the same model, not including vehicles on the exclusion list.

2. The shocks/struts may be from the manufacturer’s accessory catalog.

3. The shock must be on the "Alternate Approved Shock" list in these rules.

4. Any other allowed shock must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order and may not be height-adjustable. (E.g., no threaded body coil-overs or coil-over conversions.) Parts do not have to be sourced from the Tire Rack, but they must be as they would have come off the shelf from there (e.g., no revalving), or the shock must be on a specific approval list.

If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not on the "Alternate Approved Shock" list, or is not available at The Tire Rack you may write in for specific approval of that brand and model.

5. The following restrictions apply to any and all allowed shocks:

A. Only one shock damping adjustment control is allowed.

B. Suspension geometry and alignment capability, not including ride height, may not be altered by the substitution of alternate shock absorbers. Aftermarket strut housings are allowed provided that they meet the category shock requirements defined herein (i.e., that no suspension geometry changes result). This includes the position of the steering arm attachment point in the case of struts with integrated steering arms.

C. The mounting hardware shall be of the original type. The use of any shock absorber bushing material, including metal, is permitted. Pressed or bonded bushings may be removed from standard parts to facilitate the use of alternate bushings which fit in the original location without alterations to the part. This does not permit the use of an offset shock bushing. A shock absorber bushing may be implemented as a spherical bearing. The bushing attaching the end of a strut to the body or frame on a strut type suspension is a suspension bushing, not a shock bushing. For cars with a bayonet/shaft-type upper shock mount, this allowance permits the removal of the shock bushing from the upper mounting plate (e.g., drilling, cutting, burning out the bushing) and replacing it with another bushing. This also includes shock bushings located in control arms, etc. This does not allow other modifications to the plate itself or use of an alternate plate.

D. To facilitate the installation of commonly available aftermarket shock absorbers, struts, or strut inserts whose shaft size is larger than the center hole of an upper shock mount assembly, that hole may be enlarged by the minimum necessary to accommodate the shock shaft size, provided the following restrictions are met:

1. The enlarged hole must remain concentric with the original configuration.

2. The enlargement of the hole does not require modification of a bearing (as opposed to a washer, sleeve, or plate).

3. Neither the hole enlargement nor the location of the shock shaft changes any alignment parameter. Provided these constraints are met, this permits enlarging of the center hole in an upper shock mount with an integrated rubber bushing, where the bushing is integral to the mount and bonded to the plate and the mount is provided by the OE as an assembly. This includes drilling out and/or removal of the metal sleeve.

6. Bump stops may be substituted or modified, provided they are in the same location as stock. (Shocks/struts with an internal bump stop on the shock shaft meet this requirement.)

7. A hole may be added to interior body panels, the engine compartment, the trunk and/or a strut bar to provide access to the adjustment mechanism on a shock absorber. The hole may serve no other purpose and may not be added through the exterior body panels.

A set of springs or "Lowering Kit" may be substituted providing that the number, type, system of attachment and attachment points are not altered, except as noted below:

1. The set of springs/lowering kit may be OE from the same model and generation car.

2. The set of springs/lowering kit may be from the manufacturer’s accessory catalog.

3. Any other allowed set of springs or lowering kit must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order.

A. Parts do not have to be sourced from Tire Rack, but they must be as they would have come off the shelf from there, or the set of springs must be on a specific approval list.

B. If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not available at Tire Rack you may write in for specific approval of that brand and model.

Substitution, addition or removal of sway bars (at one or both ends of the car) and supporting hardware (brackets, end links, bushings, etc.) is permitted, subject to the following restrictions.

1. Substitution, addition or removal of sway bars may serve no other purpose than that of a sway bar.

2. No modification to the body, frame, or other components to accommodate sway bar addition or substitution is allowed. Non-standard lateral members which connect between the brackets for the bar are not permitted.

3. A substituted sway bar must run the OE route, and mount to the OE places.

4. The sway bar and mounting brackets may be OE from the same model car.

5. The sway bar may be from the manufacturer’s accessory catalog.

6. Any other allowed sway bar must be commonly available (or have been available) at SCCA supporting partner Tire Rack, for regular retail sales and without custom order.

A. Parts do not have to be sourced from Tire Rack, but they must be as they would have come off the shelf from there, or the set of springs must be on the specific alternate approval list.

B. If you believe there is a commonly available retail unit which otherwise fits the intent of these Rules but is not available at Tire Rack you may write in for specific approval of that brand and model.

C. Tire Rack availability is not required for brackets, end links and other mounting hardware.

You can install a 2-point strut brace if there were no strut braces, or replace a 2-point with a 2-point, or replace a 3-point with a 3-point.

1. Both the front and rear suspension may be adjusted through their designed range of adjustment by use of factory adjustment arrangements or by taking advantage of inherent manufacturing tolerances. This encompasses both alignment and ride height parameters if such adjustments are provided by the standard components and specified by the factory as normal methods of adjustment. However, no suspension part may be modified for the purpose of adjustment unless such modification is specifically authorized by the factory shop manual.

2. If offered by the manufacturer for a particular model and year, the use of shims, special bolts, removal of material to enlarge mounting holes, and similar methods are allowed, and the resulting alignment settings are permitted even if outside the normal specification or range of specifications recommended by the manufacturer. If enlarging mounting holes is specifically authorized but no material removal limits are specified, material removal is restricted to the amount necessary to achieve the maximum factory alignment specifications.

3. Ride height may only be altered by factory adjustments or as incidental to allowed modifications.

4. Changes in alignment parameters that result directly from the use of the allowed components are permitted.

5. For strut-type suspensions, either camber bolts or camber plates may be installed, provided they are a commercially available product intended for the specific application. Resulting ride height changes from installation are permitted. For camber bolts, modification of the strut ears is not permitted unless specified in the service manual or a TSB by the manufacturer, and a maximum of one camber bolt per corner is allowed. For camber plates, any type of bearing or bushing may be used in the camber plate attachment to the strut. The drilling of holes to allow installation is not permitted. The center clearance hole may not be modified.

1. The make of spark plugs, points, ignition coil and high-tension wires is unrestricted including spark plug wires having an in-line capacitor. Substitution or addition of ignition coil mounting brackets is permitted, provided they affix to the original standard location and serve no other purpose. (Modification of the distributor cap for the purpose of installing allowed non-standard components is not permitted.)

2. On cars made prior to January 1, 1968, any ignition system using a standard distributor without modification may be used.

3. Ignition settings may not be mechanically adjusted outside factory specifications.

4. Additional battery hold-down hardware may be added to supplement the standard equipment in order to meet safety inspection requirements. It may serve no other purpose.

5. Tire pressure monitoring systems (TPMS) may be disabled. Altering the signal to the TPMS is permitted.

6. On cars without the ability to turn off anti-lock braking systems (ABS), electronic stability control and/or traction control (ESC/TC) from the manufacturer, modifications to defeat the ABS/ESC/TC are permitted. These modifications are limited to altering the inputs to the ABS/ESC/TC processor (e.g., removing fuses, unplugging yaw or steering angle sensors, altering signals, etc.) and may serve no other purpose. Any codes or error lights resulting from ABS/ESC/TC modifications are permitted.

7. On cars equipped with computer-aided gear selection or “skip-shift” features from the manufacturer, modifications to defeat the skip-shift feature are permitted any may serve no other purpose.

8. On cars with electronically-controlled exhaust pipe valving downstream of the catalytic converter, devices may be added to satisfy the PCM/ECU provided the OE component is still installed. Such devices shall perform no other function.

9. The addition of electrical grounding cables and associated distribution blocks/terminals is permitted. Holes may be drilled for mounting only. This does not permit the use of electrical enhancement components such as condensers, voltage controllers, etc.

1. OE traction control systems may be electrically disabled, but not removed or altered in any other way.

2. The engine management system parameters and operation of internal combustion engines may be modified only via the methods listed below.

A. OE ECU software may be reprogramed, but no changes to the factory ECU hardware are permitted.

B. Any OE OBD2 or newer communications port functionality must remain.

C. The Check Engine Light (CEL) or Malfunction Indicator Light (MIL) may be disabled via software.

D. Only OE sensors may be used for engine management.

E. Ignition timing may be set at any point on factory adjustable distributor ignition systems.

1. The air intake system up to, but not including, the engine inlet may be modified or replaced.

A. The engine inlet is the throttle body, carburetor, compressor inlet, or intake manifold, whichever comes first relative to the intake flow.

B. The existing structure of the car may not be modified for the passage of ducting from the air cleaner to the engine inlet. Holes may be drilled for mounting.

C. Emissions or engine management components in the air intake system, such as a PCV valve or mass airflow sensor, may not be removed, modified, or replaced, and must retain their original function along the flow path.

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

A. Radiator core dimensions (width, height, thickness) cannot be smaller than the standard part.

B. Radiator must mount to OE radiator mounts.

C. 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).

D. The installation of water expansion tanks is allowed. A water expansion tank is the container which catches overflow coolant.

E. Thermostats may be added or substituted. A thermostat is a device which controls the passage of water.

F. Modifications necessary for additional radiators must be the minimum required for installation.

1. Engine Service Limits

A. Engines may be rebored to the manufacturer’s first standard overbore, not to exceed 0.020 inch (0.508 mm). Sleeving is allowed to repair to the standard bore. Only OE-type standard or first overbore pistons of the same configuration and of the same or greater weights are permitted. No interchange between cast and forged pistons is allowed.

B. Valve seats and guides in older engines originally designed for leaded fuel may be only substituted with alternate components if the dimensions are the same as those of the standard components.

1. Transmission and differential coolers and lines may be added.

2. Shifter bushings may be replaced; non-metal bushings may not be replaced with metal bushings.

1. Any part of the exhaust system beyond (downstream from) the last catalytic converter, if so equipped, may be substituted or removed provided the system exits the car in the original location and meets safety requirements.

2. Vehicles equipped with exhausts that exit in multiple locations may change to a single outlet in any of the original locations.

3. Stainless steel heat exchangers are permitted only if the physical dimensions and configuration remain unchanged.

4. Modifications of any type, including additions to or removal of, the catalytic converters, thermal reactors, or any other pollution control devices in the exhaust system are not allowed and the system must be operable.

5. Replacement catalytic converters must be OE if the vehicle has not exceeded the warranty period as mandated by the EPA. Converters must be of the same type and size and used in the same location as the original equipment converter(s). This does not allow for a high-performance unit. If the vehicle has exceeded the warranty period, replacement catalytic converters must be OE-type.

6. Exhaust hangers which are welded on the car are considered part of the body and may not be changed or removed.

1. Any oil filter may be added if not originally equipped. Canister-type oil filters may be replaced with a spin-on type filter using a minimum amount of hardware and connecting lines.

2. Any oil or grease, including synthetic, is permitted.

3. Coolers and lines may be added for lubricating and hydraulic-type fluids (i.e. not fuel).

4. The installation of oil catch tanks or oil separators is allowed provided the function of the PCV system remains intact.

5. Cars with combustion chamber oil injection systems (such as those in rotary engines) may supplement the standard engine lubrication with additional oil supplied through the standard fuel delivery system.

1. Engine “dress-up” items such as chrome dipsticks and non-standard filler caps are permitted, provided they serve no other purpose.

2. 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.

3. Silicone replacement hoses are permitted as alternate components provided they meet standard parameters with regard to size, shape, location, and performance equivalence.

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.

1. 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.

2. Substitute parts which provide improvements in performance (e.g., superior gearing, lighter weight, better camshaft profile, etc.) are not permitted under this allowance.

1. Sport and Tuner Category vehicles will use fuel which is “Federally approved for use on public highways.” This does not allow racing-type fuels which are available at service station pumps.

2. Fuels comprised of more than 15% ethanol may only be used when specified by the manufacturer for regular road use (e.g., in the owner’s manual for flex-fuel vehicles, not including emergency situations).

3. Propane or Compressed Natural Gas (CNG) fuel may be used in any category provided that the following conditions are met:

A. The tank must be located in a safe location on the car and be firmly and securely mounted. This does not permit the cutting of vehicle sheet metal (e.g., the trunk floor) for tank installation.

B. The tank must conform to Federal and local container standards and have an emergency relief/cut-off control.

C. For use of propane or CNG as a fuel, no changes to the induction system of the engine may be made with the exception of the necessary fuel lines to the carburetor or fuel injection. There may also be no other engine parts changed.

D. The entire system must meet local ordinances covering the use and transmission of compressed gas.

E. Propane or CNG may not be used in combination with another fuel.

1. Cars listed as eligible in and prepared to the current SCCA Solo Street Category Rules are permitted to compete in their listed Time Trials Sport classes and are not restricted to Sport Class tire-width limits. Solo SSR-class vehicles are restricted to Sport Category minimum tread wear ratings. Vehicles with this allowance are not permitted to interchange preparation Rules.

2. Cars listed as eligible in and prepared to the current SCCA Autocross Solo Spec Coup (SSC) Rules are permitted to compete in Time Trials Sport Class 5 (S5). SSC cars with this allowance are not permitted to interchange preparation Rules and must run on the spec tire.

3. Cars listed as eligible in and prepared to the previous SCCA Road Race Showroom Stock Rules are permitted to compete in their respective Time Trials Sport classes provided they run on Time Trials legal tires. Vehicles with this allowance are not permitted to interchange preparation Rules otherwise.

We're gonna put some of the coolest cars here. Part of what will be cool about them is they are awesome enough to be on the exclusion list.